Thread Rating:
  • 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Rosetta stone"7 hours of terror" Philae approaches 67P/Churyumov-Gerasimenko
Land? / Not Land.

Alive? / Not Alive.

Up^ / Not Up^
 
This thread has uncertainly been a " perihelion cliff "-hanger so far...

What will become of Shroedinger's Philae???


Preparing for perihelion


Posted on 13/07/2015 by emily

[Image: Comet_around_perihelion_node_full_image_2.jpg]

Rosetta’s investigations of its comet are continuing as the mission teams count down the last month to perihelion – the closest point to the Sun along the comet’s orbit – when the comet’s activity is expected to be at its highest.
Rosetta has been studying Comet 67P/Churyumov–Gerasimenko for over a year now, with observations beginning during the approach to the comet in March 2014. This included witnessing an outburst in late April 2014 and the revelation of the comet’s curious shape in early July.
After arriving at a distance of 100 km from the double-lobed comet on 6 August, Rosetta has spent an intense year analysing the properties of this intriguing body – the interior, surface and surrounding dust, gas and plasma.
Comets are known to be made of dust and frozen ices. As these ices are warmed by the Sun, they turn directly to vapour, with the gases dragging the comet’s dust along with it. Together, the gas and dust create a fuzzy atmosphere, or coma, and often-spectacular tails extend tens or hundreds of thousands of kilometres into space.
While ground-based observations can monitor the development of the coma and tail from afar, Rosetta has a ringside seat for studying the source of this activity directly from the nucleus. One important aspect of Rosetta’s long-term study is watching how the activity waxes and wanes along the comet’s orbit.
The comet has a 6.5 year commute around the Sun from just beyond the orbit of Jupiter at its furthest, to between the orbits of Earth and Mars at it closest.
Rosetta rendezvoused with the comet around 540 million km from the Sun. Today, 13 July, a month from perihelion, this distance is much smaller: 195 million km. Currently travelling at around 120 000 km/h around their orbit, Rosetta and the comet will be 186 million km from the Sun by 13 August.
“Perihelion is an important milestone in any comet’s calendar, and even more so for the Rosetta mission because this will be the first time a spacecraft has been following a comet from close quarters as it moves through this phase of its journey around the Solar System,” notes Matt Taylor, ESA’s Rosetta project scientist.
“We’re looking forward to reaching perihelion, after which we’ll be continuing to monitor how the comet’s nucleus, activity and plasma environment changes in the year after, as part of our long-term studies.”
See our FAQ below for more on what can you expect from perihelion and the activities planned around it.
Perihelion basics
What is perihelion exactly?
Perihelion is the closest point a Solar System object gets to the Sun along its orbit

 

(aphelion is the term given to the most distant point,The Best Example is  July 4 on Earth...  
  RebelSmilie just nine days ago).

The term derives from ancient Greek, where ‘peri’ means near and ‘helios’ means Sun.

How close to the Sun will the comet be at perihelion?
Comet 67P/Churyumov–Gerasimenko is on a 6.5 year elliptical orbit around the Sun which takes it between 850 million km (5.68 AU) from the Sun at its most distant, just beyond the orbit of Jupiter, and 186 million km (1.24 AU) at its nearest, between the orbits of Earth and Mars. As a comparison, Earth orbits the Sun at an average distance of 149 million km (1 Astronomical Unit, or AU).
At what moment does perihelion occur?
For this comet, the upcoming perihelion occurs at 02:03 GMT on 13 August 2015. The previous perihelion took place on 28 February 2009.
The comet during perihelion
What happens to the comet during perihelion? Will there be a big difference in activity in the coming weeks?
The comet’s activity has been growing over the last year that Rosetta has been at the comet. This is an incremental process brought about by the increase in solar energy incident on the comet, warming up its frozen ices that subsequently sublimate. Rosetta has been witnessing this gradual rise, and scientists expect that this activity will reach a peak during August and September. Outbursts are possible, but unpredictable.
Other comets plunge into the Sun at perihelion, what about this one?
Comet 67P/Churyumov–Gerasimenko does not get close enough to the Sun to be destroyed by it; its closest point is actually further than Earth ever gets to the Sun and, furthermore, the comet has survived many previous orbits. It is not, for example, classed as a ‘sungrazer’ like Comet C/2012 S1 ISON, which broke apart during its perihelion passage in November 2013.
Will the comet break apart during perihelion?
The comet has not broken apart during its many previous orbits, so it is not expected to do so this time, but it cannot be ruled out. Scientists are keen to watch the possible evolution of a 500 m-long fracture that runs along the surface of the neck on the comet during the peak activity.
What happens to the comet after perihelion?
As with the last observed perihelia, we expect the comet to continue on its orbit as normal, away from the Sun and back towards the outer Solar System again. Thanks to the heat absorbed during perihelion, the activity is expected to remain high for a couple of months before gently decreasing towards the moderate activity levels seen earlier in the mission, allowing Rosetta to get closer to the nucleus again.
Rosetta and Philae during perihelion

Does Rosetta have to do any special manoeuvres for perihelion?
Perihelion is a very different milestone to the other events such as waking up from hibernation, arriving at or landing on the comet where critical operations had to be carried out. Perihelion is simply a moment in time, and in terms of operations, it is business as usual – no special manoeuvres are required. The mission team hopes to have Rosetta as close as possible to the comet during perihelion to perform science observations without jeopardising the safety of the spacecraft, but this distance is currently decided on a twice-weekly basis for the week ahead, so the exact distance for perihelion is not currently known. During the last few months, it has not been possible to operate closer than 150 km without running into difficulties caused by the vast amounts of dust around the comet at the present time.
Are there any special science observations that will be done at the time of perihelion?
As with operations, it is also business as usual for science observations – monitoring of the comet and its dust, gas and plasma environment will continue during perihelion. Scientists are particularly keen to study the southern hemisphere of the comet, which has been in full sunlight only since May.
How long will it take Rosetta to communicate with Earth on 13 August?
The one-way signal travel time on 13 August is 14 min 44 sec.
When will we see an image from the moment of perihelion?
Rosetta’s Navigation Camera takes images several times during each 24 hour Earth day for navigation purposes, while the science camera OSIRIS has dedicated imaging slots. While the imaging schedule is not currently known for perihelion, we are hoping to be able to share both NavCam and OSIRIS image(s) with you from around the time of perihelion, during the afternoon of 13 August. Note that for OSIRIS this will depend on the data prioritisation on that day and the time it takes to downlink so this cannot be guaranteed. Time is also needed to check and process the images for release (for both NavCam and OSIRIS). We will update this section if/when more information about the timing of the image release(s) is known.
Will Rosetta and Philae be safe during perihelion?
Owing to the large amounts of dust, Rosetta will continue to operate at a safe distance from the comet throughout perihelion. We cannot predict any sudden increases in activity of the comet in advance, but the spacecraft safety remains – as always – a priority.
Philae is on the surface of the comet, although its exact location remains unknown. Having regained communications with Rosetta on 13 June the link has been unpredictable and intermittent. The mission teams are carefully analysing the situation and hope that Philae will be operational during perihelion (separate updates on Philae’s condition will be made via the Rosetta Blog).
What will happen to the mission after perihelion?
Rosetta will continue to follow the comet as it moves back towards the outer Solar System, watching how the activity decreases over time and monitoring any post-perihelion changes that may occur. The Rosetta mission is scheduled to continue until September 2016, when the nominal planning would see Rosetta spiral down to the surface of the comet, where operations would likely end.
Observing the comet from Earth during perihelion
Why is perihelion interesting for astronomers?
Near perihelion, comets reach their highest level of brightness, releasing large amounts of gas and dust. Possible outbursts and other unpredictable events might also take place around perihelion, so it is extremely important to obtain as many observations as possible during this period. While ground-based observations provide large-scale context for Rosetta’s measurements, Rosetta’s close-up data provide in turn the possibility to calibrate many of the observations made from the ground. This unique opportunity will also improve the study and interpretation of ground-based observations of other comets.
How close to Earth will the comet be at perihelion? Is this the closest it gets to Earth?
While the distance between the comet and the Sun decreases steadily until perihelion, before increasing again afterwards up to aphelion, the distance between Earth and the comet depends on their relative positions in the Solar System. At perihelion, the comet is 265 million km from Earth, but it will be closer (222 million km) during January–February 2016. Follow the positions of Rosetta and the comet through the Solar System using our Where is Rosetta? tool.
Will astronomers be observing the comet at perihelion?
Yes, a large network of professional and amateur astronomers has been observing the comet from across the globe in the past months. Observations with professional telescopes are planned every night around perihelion, relying on several robotic telescopes in many locations, and spectroscopic observations will be performed once a week. More details of the professional campaign are available here.

How can I observe the comet at perihelion?
Unfortunately, even at perihelion, the comet is too faint to be seen with the naked eye. To observe the comet, you will need a good telescope: a minimum of a 20 cm-aperture telescope is recommended. Guidance on how amateur astronomers can observe the comet is available here.
Until when is it possible to observe the comet from Earth?
The comet is currently passing from the southern sky to the northern sky, so its visibility depends on where you live. Around the time of perihelion, it can be observed from Earth in the early morning hours, just before sunrise. It will remain relatively close to the Sun in the sky, and thus observable in the early morning, for several months. Then, the comet will be in the night sky between December 2015 and March 2016, which will be the prime time for ground-based observations. By the middle of 2016 it will likely be too faint to see except by large telescopes owing to its distance from the Sun and Earth, and it will also start moving behind the Sun as seen from Earth.
Media
Will there be any special events to mark the occasion of perihelion?
Members of the public and media are invited to join an online Google+ Hangout on 13 August, during which we hope have one or more images on the ground from around the time of perihelion. Time and guests to be announced nearer the time.
How can I follow online?
You can follow the mission in a number of ways (see esa.int/rosetta for an overview). On the day you can follow on Twitter, with official updates from @ESA_Rosetta using the hashtag #perihelion2015. Information will also be provided by the Rosetta blog and on the Rosetta Mission Facebook page. The image(s) from perihelion will be published on our main ESA web portal, esa.int, in an official press release. The Google+ Hangout will also be advertised on esa.int and will be available to watch live via ESA’s G+ page and later as a replay on G+ and ESA’s YouTube channel.
About Rosetta
Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta's Philae lander is contributed by a consortium led by DLR, MPS, CNES and ASI.
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
I can't wait to show my Grandkid this!


More Space Cartoons!!!
Logan will dig it!

Good One ESA!!!
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
[Image: Rotating_view_of_comet_on_14_July_2014_n...mage_2.gif]

[Image: Comet_rotation_axis_node_full_image_2.jpg]

Getting to know Rosetta’s comet: boundary conditions


In January the first maps of Comet 67P/Churyumov-Gerasimenko were published, identifying 19 geomorphologically distinct regions on its surface. Six months on and much more work has been done on refining the boundaries between these regions. This blog post showcases some of the OSIRIS images acquired from close orbit and presented in a new paper that have enabled an in-depth study of the different regions and their boundaries. This post was prepared with inputs from lead author M. Ramy El-Maarry from the University of Bern, who introduces this post with an inside story on how some of the regional names were chosen:

“Early on in the mapping phase, we decided on naming the regions of the comet using names of ancient Egyptian deities. We wanted to adhere to the ancient Egyptian theme of the mission and have a large inventory of names if needed. Luckily, ancient Egyptians had so many deities in their long history that made this an easy decision. Moreover, many of the names were catchy, easy to remember, and more importantly, easy to pronounce. I remember we initially tried using names of ancient cities and we were coming across a lot of names that were very difficult to wrap your tongue around, even for an Egyptian like me! So we decided to use the following naming convention: gods for the ‘body’ lobe and goddesses for the ‘head’. We picked Hapi for the neck since Hapi is the Nile god, and we figured that he should separate the lobes in the same way that the Nile splits Egypt into an eastern and western side. Of course, there were obvious names to discard (such as Osiris!) so we decided to skip on all 'world-famous' gods such as R’a and Amun, partly because they have been used before in other missions, but also to introduce people to lesser-known names.
In another story, we decided on using Imhotep for one of the most notable regions on the comet. Imhotep was one of the most brilliant figures of the ancient world as a scientist, engineer, and a physician. Luckily for us, there were no Nobel prizes in ancient Egypt, so when Imhotep died, he was deified by ancient Egyptians to credit his accomplishments, which meant we could actually use his name as a nice tribute from our side!”
Around Aten, Aker, Babi and Khepry

[Image: Comet_boundaries_Aten_Aker_Babi_and_Khep...mage_2.jpg]
This set of images focuses on a number of boundaries on the comet’s large lobe, in particular on the smaller regions Aten, Aker, Babi and Khepry, their relationship to each other and to the larger and perhaps more familiar Seth and Ash regions nearby. The transition into the smooth Hapi neck region is also indicated in the context image. The insets show interesting contrasts in surface textures at the boundaries of Aten and Babi (left) and Khepry, Babi and Aker (right).

Aten is dominated by a large elongate depression surrounded by the brittle and dusty material of Ash and Babi. El-Maarry et al suggest that its sharp sides and irregular shape could point to a rapid and perhaps violent burst of activity. The close-ups show rubble and boulders inside the depression, the largest of which reach up to 30m in diameter. The rubble suggests rock fall events, most likely from the rim of the depression.

The smooth deposits on the surrounds make a striking contrast and mark the boundary with Babi. In the middle inset (left) this dusty covering can be seen overlying regions of significant layering, which could be parts of Seth extending below the dusty deposits of Ash and into Babi. Indeed, Babi hosts one quasi-circular structure reminiscent of Seth that rises 60-80m over Khepry, marking the boundary in this area (see insets at top and middle right). Well-defined ridges also separate the lower-lying Babi from Aker and Seth.

Khepry and Aker both have a rough, consolidated appearance, exhibit linear markings but very few boulders. Aker has a slightly smoother surface texture than Khepry but they both contain very smooth patches 50–100m across that are located in topographical lows. The inset at bottom right shows a close-up view of one of these smooth deposits close to the Khepry-Aker border.

[b]From Anubis and Atum to Hapi and Anuket[/url][/b]

[Image: Comet_boundaries_Anubis_and_Atum_to_Hapi...mage_2.jpg]
This image set highlights the boundaries between Anubis, Atum and Seth on the large lobe, and the transition between the neck and Anuket on the small lobe.

Atum is a rather complex, rough-textured region with linear features that are similar to some of the structures observed in Imhotep and interpreted as terraces resulting from erosion of an underlying layered terrain. Atum borders the smooth-textured Anubis region and almost encloses it, with a well-defined ridge separating it from Seth.

A notable feature between the boundary of Anubis with Atum is a set of parallel curved lineaments. This feature could indicate possible folding of the surface, or the surface expression of buried terraces.

Nearby, Atum shares a boundary with the Anuket region on the head lobe, the latter of which appears to traverse the neck region in an area devoid of the smooth deposits that define the transitional Hapi region.

Anuket has a rough surface with numerous boulders but appears to smooth out away from the neck and toward the boundary with dust-covered Ma’at. The smoother regions seen in Anuket are patches of dust, suggesting that material similar to that of Anuket’s surface may extend underneath the dust-covered Ma’at region.

[b]On the head: Ma’at, Maftet, Nut and Serqet[url=http://www.esa.int/spaceinimages/Images/2015/07/Comet_boundaries_Ma_at_Maftet_Nut_and_Serqet]
[/b]

[Image: Comet_boundaries_Ma_at_Maftet_Nut_and_Se...mage_2.jpg]
The Nut depression and Serqet are two of the smallest regions on the surface of the comet in terms of surface area, but yet show significant morphological diversity. The Serqet region is defined by a ridge of consolidated material with an adjacent flat and smooth, dusty plain, which forms the rim of Nut. Nut is classified as a depression and is extensively infilled with boulders, perhaps from the erosion of Serqet and an influx of dust similar to that seen in Ma’at.

Ma’at’s dust-covered texture resembles Ash on the comet’s body. It also exhibits sharp outcrops of materials emerging from the dust, which show similarities to the more consolidated material in Anuket. Ma’at grades into Maftet where the dust gradually thins out into rough, terraced and fractured terrain pockmarked with irregularly shaped shallow depressions. Patches of the fading dusty material along this boundary show a pitted texture, which El-Maarry et al suggest is an ice-rich material that may be undergoing desiccation through sublimation. The dust covered regions both on the head and on the body of the comet are likely linked to ‘airfall’ deposition from more active regions.


[b]Explore the comet in 3D[/b]

Further details of the comet’s boundaries are provided in stunning anaglyph images that are possible when two images of similar spatial resolution and illumination are taken of the same region and can be appropriately co-registered. The following anaglyphs were used to identify and assess topographical boundaries between adjacent regions and changes in relief in the latest study. To best enjoy the 3D effect, please use red-blue/green “3D” glasses.



http://blogs.esa.int/rosetta/files/2015/...4x1024.jpg

http://blogs.esa.int/rosetta/files/2015/...24x596.jpg

http://blogs.esa.int/rosetta/files/2015/...24x596.jpg

Getting to know Rosetta’s comet: boundary conditions

[Image: Comet_rotation_and_regions.jpg]

OSIRIS images showing Comet 67P/Churyumov–Gerasimenko in different orientations. Rotation axes have been added; in the middle two panels the rotation axis is almost toward the viewer, that is, providing a north polar view.
Right: the same images with regional boundaries and nomenclature added.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Philae probe finds evidence that comets can be cosmic labs

July 30, 2015 by By Frank Jordans

[Image: philaeprobef.jpg]
The July 20, 2015 photo released by the European Space Agency ESA on Tuesday, July 28, 2015 shows an image of the comet 67P/Churyumov-Gerasimenko with its coma taken by the Navcam camera of the Rosetta orbiter from a distance of 171km (106 miles) from the comet center. (AP Photo/ESA/Rosetta/Navcam)


Scientists say the Philae space probe has gathered data supporting the theory that comets can serve as cosmic laboratories in which some of the essential elements for life are assembled.


Philae, which is part of the European Space Agency's Rosetta mission, used two separate instruments to 'sniff' for molecules during its bumpy landing on comet 67P/Churyumov-Gerasimenko last November.
In an article published Thursday in the journal Science, researchers said they spent months analyzing the data and concluded that 67P contains at least 16 organic compounds. Four of them, including acetone, hadn't been detected on a comet before.

"Comets are loaded with all the raw materials like water, CO2, methane, ammonia, needed to assemble more complex organic molecules, perhaps sparked by UV-photons from the Sun or cosmic rays, or in the shock that occurs when a comet hits the surface of a planet like the young Earth," said Mark McCaughrean, a senior scientific adviser at the European Space Agency.

It's not yet known whether the complex molecules found in 67P were made in the early solar system and then incorporated into the comet or formed there later, he said. "Either way, it seems that comets are pretty good places to find the building blocks of molecules which later on could be used for life."
McCaughrean, who wasn't directly involved in the study, dismissed recent reports that evidence of life itself had been found on the comet. But he said the prebiotic compounds that were detected might be coaxed into even more complex molecules such as amino acids, including by a planetary impact.
Proteins, fundamental to living organisms, are made from long chains of amino acids, and the simplest one, glycine, was even detected in material collected from the tail of another comet by NASA's Stardust mission a few years ago.
The Philae scientists have not found any amino acids on 67P yet, but that's not to say they aren't there. As Philae was only able to perform experiments for 60 hours before its batteries were depleted, scientists were unable to complete some of the work they had hoped to carry out.
The space probe woke up from hibernation last month, but the German space agency DLR that operates Philae has not yet been able to establish a robust connection to restart the scientific experiments. Still, scientists are hopeful that this will be possible as the probe and its mother ship Rosetta, which is orbiting the comet, accompany 67P on its journey through space.
The next important event in the mission will take place on Aug. 13, when the comet comes closest to the sun, a point known as perihelion.
Along with their findings on the comet's chemical composition, scientists also published new insights about its rocky terrain and its unexpectedly hard surface, which may prove crucial to future comet missions.



Quote:"We have definitely learned at least one thing with this first comet landing:
 LandBouncingNot Land is a bigger problem than a possible sinking into the ground," said Philae to project manager Stephan Ulamec.


[Image: 1x1.gif] Explore further: Scientists record thud of Philae's comet landing
More information: The landing(s) of Philae and inferences about comet surface mechanical properties, www.sciencemag.org/lookup/doi/10.1126/science.aaa9816
Journal reference: Science


Read more at: http://phys.org/news/2015-07-philae-prob...c.html#jCp

Wickramasinghe will have his day?




Rosetta shows how comet interacts with the solar wind

July 30, 2015

 



Rosetta is making good progress in one of its key investigations, which concerns the interaction between the comet and the solar wind.



The solar wind is the constant stream of electrically charged particles that flows from the Sun, carrying its magnetic field out into the Solar System. Like all comets, 67P/Churyumov–Gerasimenko must navigate this flow in its orbit around the Sun.

It is the constant battle fought between the comet and the solar wind that helps to sculpt the comet's ion tail. Rosetta's instruments are monitoring the fine detail of this process.





Using the Rosetta Plasma Consortium Ion Composition Analyzer, Hans Nilsson from the Swedish Institute of Space Physics and his colleagues have been studying the gradual evolution of the comet's ion environment. They have seen that the number of water ions – molecules of water that have been stripped of one electron – accelerated away from the comet increased hugely as 67P/C-G moved between 3.6AU (about 538 million km) and 2.0AU (about 300 million km) from the Sun. Although the day-to-day acceleration is highly variable, the average 24-hour rate has increased by a factor of 10 000 during the study, which covered the period August 2014 to March 2015.

The water ions themselves originate in the coma, the atmosphere of the comet. They are placed there originally by heat from the Sun liberating the molecules from the surface ice. Once in gaseous form, the collision of extreme ultraviolet light displaces electrons from the molecules, turning them into ions. Colliding particles from the solar wind can do this as well. Once stripped of some of their electrons, the water ions can then be accelerated by the electrical properties of the solar wind.





Not all of the ions are accelerated outwards, some will happen to strike the comet's surface. Solar wind particles will also find their way through the coma to hit home. When this happens, they cause a process called sputtering, in which they displace atoms from material on the surface – these are then 'liberated' into space.

Peter Wurz from the University of Bern, Switzerland, and colleagues have studied these sputtered atoms with Rosetta's Double Focussing Mass Spectrometer (DFMS), which is part of the ROSINA experiment.





They have so far discovered sodium, potassium, silicon and calcium, which are all present in a rare form of meteorites called carbonaceous chondrites. There are differences in the amounts of these atoms at the comet and in these meteorites, however. While the abundance of sodium appears the same, 67P/C-G shows an excess of potassium and a depletion of calcium.

Most of the sputtered atoms come from the winter side of the comet. Although this is the hemisphere that is mostly facing away from the Sun at present, solar wind particles can end up striking the surface because they are deflected during interactions with ions in the comet's coma. This can be a significant process so long as the density of the coma ions is not too large. But at some point the comet's atmosphere becomes dense enough to be a major defence, protecting the icy surface.

As the comet gets closer to the Sun, the sputtering will eventually stop because the comet will release more gas and the coma will become impenetrable. When this happens, the solar wind ions will always collide with atoms in this atmosphere or be deflected away before striking the surface.

The first evidence that this deflection is taking place at 67P/C-G has been measured with the Rosetta Plasma Consortium Ion and Electron Sensor, by Thomas Broiles of the Southwest Research Institute (SwRI) in San Antonio, Texas, and colleagues.

Their observations began on 6 August 2014 when Rosetta arrived at the comet, and have been almost continuous since. The instrument has been measuring the flow of the solar wind as Rosetta orbits 67P/C-G, showing that the solar wind can be deflected by up to 45° away from the anti-solar direction.

The deflection is largest for the lighter ions, such as protons, and not so much for the heavier ions derived from helium atoms. For all ions the deflection is set to increase as the comet gets closer to the Sun and the coma becomes ever denser.

As all this happens, Rosetta will be there to continue monitoring and measuring the changes. This was the raison d'être for the rendezvous with this comet. Previous missions have taken snapshots during all too brief fly-bys but Rosetta is showing us truly how a comet behaves as it approaches the Sun.

[Image: 1x1.gif] Explore further: Rosetta's comet sings strange, seductive song

More information: This article is based on four papers:

"Evolution of the ion environment of comet 67P/Churyumov-Gerasimenko: Observations between 3.6 and 2.0 AU" by H. Nilsson et al., accepted for publication in Astronomy and Astrophysics

"Rosetta observations of solar wind interaction with the comet 67P/Churyumov-Gerasimenko" by T.W. Broiles et al., accepted for publication in Astronomy and Astrophysics

"Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko" by P. Wurz et al., accepted for publication in Astronomy and Astrophysics, dx.doi.org/10.1051/0004-6361/201525980

"Dynamical features and spatial structures of the plasma interaction region of 67P/Churyumov–Gerasimenko and the solar wind" by C. Koenders et al., published in Planetary and Space Science, January 2015. dx.doi.org/10.1016/j.pss.2014.11.014

Journal reference: Astronomy and Astrophysics [Image: img-dot.gif] [Image: img-dot.gif] Planetary and Space Science [Image: img-dot.gif] [Image: img-dot.gif]

Provided by: European Space Agency




Read more/ VIDEO at: http://phys.org/news/2015-07-rosetta-com...r.html#jCp
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Science on the surface of a comet


July 31, 2015

[Image: scienceonthe.gif]
Descending to a comet. Credit: European Space Agency

Complex molecules that could be key building blocks of life, the daily rise and fall of temperature, and an assessment of the surface properties and internal structure of the comet are just some of the highlights of the first scientific analysis of the data returned by Rosetta's lander Philae last November.

Early results from Philae's first suite of scientific observations of Comet 67P/Churyumov-Gerasimenko were published today in a special edition of the journal Science.
Data were obtained during the lander's seven-hour descent to its first touchdown at the Agilkia landing site, which then triggered the start of a sequence of predefined experiments. But shortly after touchdown, it became apparent that Philae had rebounded and so a number of measurements were carried out as the lander took flight for an additional two hours some 100 m above the comet, before finally landing at Abydos.
 
Some 80% of the first science sequence was completed in the 64 hours following separation before Philae fell into hibernation, with the unexpected bonus that data were ultimately collected at more than one location, allowing comparisons between the touchdown sites.
Inflight science
After the first touchdown at Agilkia, the gas-sniffing instruments Ptolemy and COSAC analysed samples entering the lander and determined the chemical composition of the comet's gas and dust, important tracers of the raw materials present in the early Solar System.
COSAC analysed samples entering tubes at the bottom of the lander kicked up during the first touchdown, dominated by the volatile ingredients of ice-poor dust grains. This revealed a suite of 16 organic compounds comprising numerous carbon and nitrogen-rich compounds, including four compounds – methyl isocyanate, acetone, propionaldehyde and acetamide – that have never before been detected in comets.
Meanwhile, Ptolemy sampled ambient gas entering tubes at the top of the lander and detected the main components of coma gases – water vapour, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing organic compounds, including formaldehyde.
Importantly, some of these compounds detected by Ptolemy and COSAC play a key role in the prebiotic synthesis of amino acids, sugars and nucleobases: the ingredients for life. For example, formaldehyde is implicated in the formation of ribose, which ultimately features in molecules like DNA.
The existence of such complex molecules in a comet, a relic of the early Solar System, imply that chemical processes at work during that time could have played a key role in fostering the formation of prebiotic material.


[Image: 3-scienceonthe.jpg]
CIVA camera 4 view. Credit: European Space Agency

Comparing touchdown sites

Thanks to the images taken by ROLIS on the descent to Agilkia, and the CIVA images taken at Abydos, a visual comparison of the topography at these two locations could be made.

ROLIS images taken shortly before the first touchdown revealed a surface comprising metre-size blocks of diverse shapes, coarse regolith with grain sizes of 10–50 cm, and granules less than 10 cm across.
The regolith at Agilkia is thought to extend to a depth of 2 m in places, but seems to be free from fine-grained dust deposits at the resolution of the images.
The largest boulder in the ROLIS field-of-view measures about 5 m high, with a peculiar bumpy structure and fracture lines running through it that suggest erosional forces are working to fragment the comet's boulders into smaller pieces.
The boulder also has a tapered 'tail' of debris behind it, similar to others seen in images taken by Rosetta from orbit, yielding clues as to how particles lifted up from one part of the eroding comet are deposited elsewhere.
Over a kilometre away at Abydos, not only did the images taken by CIVA's seven microcameras reveal details in the surrounding terrain down to the millimetre scale, but also helped decipher Philae's orientation.
The lander is angled up against a cliff face that is roughly 1 m from the open 'balcony' side of Philae, with stereo imagery showing further topography up to 7 m away, and one camera with open sky above.
The images reveal fractures in the comet's cliff walls that are ubiquitous at all scales. Importantly, the material surrounding Philae is dominated by dark agglomerates, perhaps comprising organic-rich grains. Brighter spots likely represent differences in mineral composition, and may even point to ice-rich materials.

[Image: 1-scienceonthe.jpg]
Brightness variations of comet surface. Credit: European Space Agency
From the surface to the interior
The MUPUS suite of instruments provided insight into the physical properties of Abydos. Its penetrating 'hammer' showed the surface and subsurface material sampled to be substantially harder than that at Agilkia, as inferred from the mechanical analysis of the first landing.
The results point to a thin layer of dust less than 3 cm thick overlying a much harder compacted mixture of dust and ice at Abydos. At Agilkia, this harder layer may well exist at a greater depth than that encountered by Philae.
The MUPUS thermal sensor, on Philae's balcony, revealed a variation in the local temperature between about –180ºC and –145ºC in sync with the comet's 12.4 hour day. The thermal inertia implied by the measured rapid rise and fall in the temperature also indicates a thin layer of dust atop a compacted dust-ice crust.
Moving below the surface, unique information concerning the global interior structure of the comet was provided by CONSERT, which passed radio waves through the nucleus between the lander and the orbiter.
The results show that the small lobe of the comet is consistent with a very loosely compacted (porosity 75–85%) mixture of dust and ice (dust-to-ice ratio 0.4–2.6 by volume) that is fairly homogeneous on the scale of tens of metres.
In addition, CONSERT was used to help triangulate Philae's location on the surface, with the best fit solution currently pointing to a 21 x 34 m area.
"Taken together, these first pioneering measurements performed on the surface of a comet are profoundly changing our view of these worlds and continuing to shape our impression of the history of the Solar System," says Jean-Pierre Bibring, a lead lander scientist and principal investigator of the CIVA instrument at the IAS in Orsay, France.

[Image: 2-scienceonthe.jpg]
MUPUS investigations at Abydos. Credit: European Space Agency
"The reactivation would allow us to complete the characterisation of the elemental, isotopic and molecular composition of the cometary material, in particular of its refractory phases, by APXS, CIVA-M, Ptolemy and COSAC."
"With Philae making contact again in mid-June, we still hope that it can be reactivated to continue this exciting adventure, with the chance for more scientific measurements and new images which could show us surface changes or shifts in Philae's position since landing over eight months ago," says DLR's Lander Manager Stephan Ulamec.
"These ground-truth observations at a couple of locations anchor the extensive remote measurements performed by Rosetta covering the whole comet from above over the last year," says Nicolas Altobelli, ESA's acting Rosetta project scientist.
"With perihelion fast approaching, we are busy monitoring the comet's activity from a safe distance and looking for any changes in the surface features, and we hope that Philae will be able to send us complementary reports from its location on the surface."
[Image: 1x1.gif] Explore further: Three touchdowns for Rosetta's lander
More information: Science, 31 July 2015, special issue. www.sciencemag.org/content/current
Journal reference: Science [Image: img-dot.gif] [Image: img-dot.gif]
Provided by: European Space Agency [/url]


Read more at:
http://phys.org/news/2015-07-science-surface-comet.html#jCp

Building blocks of life found among organic compounds on Comet 67P – what Philae discoveries mean

July 31, 2015 by , The Conversation


[Image: buildingbloc.jpg]
The building blocks of life are lurking on the dark and barren surface of Comet 67P. ESA/Rosetta/NAVCAM, CC BY-SA

Scientists analysing the latest data from Comet 67P Churyumov-Gerasimenko have discovered molecules that can form sugars and amino acids, which are the building blocks of life as we know it. While this is a long, long way from finding life itself, the data shows that the organic compounds that eventually translated into organisms here on Earth existed in the early solar system.

The results are published as two independent papers in the journal Science, based on data from two different instruments on comet lander Philae. One comes from the German-led Cometary Sampling and Composition (COSAC) team and one from the UK-led Ptolemy team.
The data finally sheds light on questions that the European Space Agency posed 22 years ago. One of the declared goals of the Rosetta mission when it was approved in 1993 was to determine the composition of volatile compounds in the cometary nucleus. And now we have the answer, or at least, an answer: the compounds are a mixture of many different molecules. Water, carbon monoxide (CO) and carbon dioxide (CO2) – this is not too surprising, given that these molecules have been detected many times before around comets. But both COSAC and Ptolemy have found a very wide range of additional compounds, which is going to take a little effort to interpret.
At this stage, I should declare an interest: I am a co-investigator on the Ptolemy team – but not an author on the paper. But the principal investigator of Ptolemy, and first author on the paper, is my husband Ian Wright.
Having made this clear, I hope that readers will trust that I am not going to launch into a major diatribe against one set of data, or a paean of praise about the other. What I am going to do is look at the conclusions that the two teams have reached – because, although they made similar measurements at similar times, they have interpreted their data somewhat differently. This is not a criticism of the scientists, it is a reflection of the complexity of the data and the difficulties of disentangling mass spectra.


Deciphering the data


3.3 Landings around Hat me hit.

[Image: 1-buildingbloc.jpg]
New images show Philae’s landing spots on comet when bouncing around and taking measurements. ESA/ROSETTA/NAVCAM/SONC/DLR

What are the two instruments? And, perhaps more to the point, what exactly did they analyse? Both COSAC and Ptolemy can operate either asgas chromatographs or mass spectrometers. In mass spectrometry mode, they can identify chemicals in vaporised compounds by stripping the molecules of their electrons and measuring the mass and charge of the resulting ions (the mass-to-charge ratio, m/z). In gas-chromatography mode they separate the mixture on the basis of how long it takes each component in the mixture to travel through a very long and thin column to an ionisation chamber and detector.
Either way, the result is a mass spectrum, showing how the mixture of compounds separated out into its individual components on the basis of the molecular mass relative to charge (m/z).
Unfortunately, the job doesn't end there. If it were that simple, then organic chemists would be out of a job very quickly. Large molecules break down into smaller molecules, with characteristic fragmentation patterns depending on the bonds present in the original molecule. Ethane, C2 H6 for example, has an m/z of 30, which was seen in the spectra. So the peak might be from ethane, or it might be from a bigger molecule which has broken down in the ionisation chamber to give ethane, plus other stuff.
Then again, it might be from CH2O, which is formaldehyde. Or it might be from the breakdown of polyoxymethylene. Or it might be from almost any one of the other 46 species which have an m/z of 30. Figuring out what it is exactly is a tough job and the main reason why I gave up organic chemistry after only a year – far too many compounds to study.
Of course, the teams didn't identify every single peak in isolation, they considered the series of peaks which come from fragmentation. This helps a bit, in that there are now many more combinations of compounds and fractions of compounds which can be matched.
So where does this leave us? Actually, with an embarrassment of riches. Have the teams come to the same conclusions? Sort of. They both detected compounds which are important in the pathway to producing sugars – which go on to form the "backbone" of DNA. They also both note the very low number of sulphur-bearing species, which is interesting given the abundance of sulphur in the solar system, and the ease with which it can become integrated into organic compounds.
The COSAC team suggests that nitrogen-bearing species could be relatively abundant, whilst Ptolemy found fewer of them. This is important because nitrogen is an essential element for life, and is a fundamental part of the amino acids which eventually make up the central core of DNA. Conversely, the Ptolemy team has found lots of CO2, whilst COSAC hasn't detected much.
These differences are probably related to sampling location: COSAC ingested material from the bottom of Philae, while Ptolemy sniffed at the top. Did Ptolemy breathe in cometary gases, whilst COSAC choked on the dust kicked up during the brief touchdown? If so, then the experiments have delivered wonderfully complementary sets of data.
Most importantly, both of those sets of data show that the ingredients for life were present in a body which formed in the earliest stages of solar system history. Comets act as messengers, delivering water and dust throughout the solar system – now we have learnt for certain that the ingredients for life have been sown far and wide through the 4.567 billion years of solar system history. The challenge now is to discover where else it might have taken root.
What else is certain is that both teams are keeping fingers crossed that the Philae-Rosetta communications link stabilises, so that they can get on with their analyses. This is just the start.
[Image: 1x1.gif] Explore further: Five questions about the Rosetta mission
Journal reference: Science [Image: img-dot.gif] [Image: img-dot.gif]
Source:: The Conversation


Read more at: [url=http://phys.org/news/2015-07-blocks-life-compounds-comet-67p.html#jCp]http://phys.org/news/2015-07-blocks-life-compounds-comet-67p.html#jCp
Reply
"Sic semper tyrannis"

[Image: 19296804119_40ec5a9ab1_o.png]
Quote:With three periods of observation in conditions of direct visibility between the Rosetta orbiter and Philae, the CONSERT instrument was able to determine the area (150 meters by 15 meters) where Philae is located. This made it easier to reconstruct the robot's trajectory from the first touchdown site, Agilkia, to the final landing site, Abydos. Then, by using the signals that traveled through the comet's interior, CONSERT reduced the uncertainty surrounding Philae's location (on the edge of the region named Hatmehit) to a strip measuring 21 meters by 34 meters.




Comets: Soft shell, hard core?


Date:July 30, 2015Source:University of Bern

Summary:Comet Churyumov-Gerasimenko poses new riddles: Surface material measurements performed by the Philae landing module indicate that the near surface material might have changed since its formation. Up to now, many researchers had assumed that it has remained in virtually the same state since its formation about 4.5 billion years ago.

[Image: 150730162944_1_540x360.jpg]
MUPUS on the Rosetta lander Philae. The MUPUS PEN(etrator) was deployed to a distance of about 60 cm after Philae had landed. The hammer mechanism on top of the probe was supposed to insert the thin rod - equipped with temperature sensors - into the comet’s surface. The surprisingly hard surface was able to withstand the strong hammer and prevented the probe insertion.
Credit: © ESA / ATG media lab

Comet Churyumov-Gerasimenko poses new riddles: Surface material measurements performed by the Philae landing module indicate that the near surface material might have changed since its formation. Up to now, many researchers had assumed that it has remained in virtually the same state since its formation about 4.5 billion years ago. The results of the study, in which researchers from the University of Bern were also involved, have been published in Science magazine.
Hard like frozen firn snow instead of loose and soft like dust: Apparently, the material under the surface of Comet Churyumov-Gerasimenko is far harder than many experts had expected – this was the result from measurements by the «Philae» comet lander at least. Karsten Seiferlin, planetologist and project manager at the Physics Institute at the University of Bern, was directly involved in the discovery and is the co-author of a Science article, in which the measurement results were published. The solidification of the material indicates processes, which have sustainably changed the comet or are still changing it", he says.
These findings are very significant for the Rosetta mission, "It was originally assumed that comets have remained virtually unchanged since their formation, thus providing information about the formation of planets and comets." However, the latest results from the Rosetta mission have now showed that the possibility of changes needs to be taken into consideration.
According to Seiferlin, an initial indication of a hard layer near to the surface has already resulted from the surprisingly high and far jump, which Philae made after the initial contact with the comet during its dramatic landing in November 2014. Direct evidence of the hard layer was then provided by the MUPUS instrument, which Seiferlin supervised as a project manager from 1994 to 2002 – back then still at the Institute of Planetology at the University of Münster. The actual aim of the instrument was to hammer an approx. 35 cm long rod equipped with temperature sensors (MUPUS PEN) into the ground using a hammer mechanism in order to measure the temperatures below the surface.
Philae’s hammer did not break through
But not everything went smoothly: The instrument initially worked without any errors and exactly as planned. It put the temperature sensor about 60 cm away from Philae, where the hammer then began its task and tried to hammer the measuring rod into the comet soil. When no progress was seen, the hammer’s capacity was automatically increased to the maximum force. Although the highest hammer setting was sufficient on Earth to crack aerated concrete stone or very solid snow, the planned penetration on Churyumov-Gerasimenko ultimately failed because of the unexpected hardness of the comet soil.
According to Karsten Seiferlin, the reasons for the observed hardness are unclear. It’s possible to consider both relatively recent processes, which are propelled by the strong radiation close to the sun, and far-back processes which are connected to the formation and development of Churyumov-Gerasimenko. "The comet has had 4.5 billion years to change."
A comet with amnesia
Now the scientists say it is particularly important to understand these changes as the ESA Rosetta space probe seems to be orbiting a comet, which has undergone at least some degree of modification compared to its initial state. Seiferlin: "The hoped-for witness to the formation of the solar system is suffering, as it were, from amnesia." Therefore, the statements made have to be carefully evaluated. "Like almost every time that space probes examine an as yet unknown body, everything was different to expected. Nature surprises us repeatedly and leaves us with more questions than we had before."

Story Source:
The above post is reprinted from materials provided by University of Bern. Note: Materials may be edited for content and length.

Journal Reference:
  1. T. Spohn, J. Knollenberg, A. J. Ball, M. Banaszkiewicz, J. Benkhoff, M. Grott, J. Grygorczuk, C. Huttig, A. Hagermann, G. Kargl, E. Kaufmann, N. Komle, E. Kuhrt, K. J. Kossacki, W. Marczewski, I. Pelivan, R. Schrodter, K. Seiferlin. Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko. Science, 2015; 349 (6247): aab0464 DOI: 10.1126/science.aab0464
    http://www.sciencedaily.com/releases/201...htmOrganic molecules on comets: Philae's first results from Churi prove surprisingDate:July 30, 2015Source:CNRSSummary:Organic molecules never previously observed in comets, a relatively varied structure on the surface but a fairly homogeneous interior, organic compounds forming agglomerates rather than being dispersed in the ice: these are just some of first results provided by Philae on the surface of comet Churi. These in situ findings, which contain a wealth of completely new information, reveal several differences in comparison with previous observations of comets and current models.The nucleus of comet 67P/Churyumov-Gerasimenko, or 'Churi'. It has a 5 km diameter.Credit: ESAThe nucleus of comet 67P/Churyumov-Gerasimenko, or 'Churi'. It has a 5 km diameter.Credit: ESACloseOrganic molecules never previously observed in comets, a relatively varied structure on the surface but a fairly homogeneous interior, organic compounds forming agglomerates rather than being dispersed in the ice: these are just some of first results provided by Philae on the surface of comet Churi. This work, carried out as part of ESA's Rosetta mission, involved researchers from the CNRS, Aix-Marseille Université, Université Joseph Fourier, Université Nice Sophia Antipolis, UPEC, UPMC, Université Paris-Sud, Université Toulouse III -- Paul Sabatier and UVSQ, with support from CNES. They are published on July 31, 2015 as part of a set of eight articles in the journal Science. These in situ findings, which contain a wealth of completely new information, reveal several differences in comparison with previous observations of comets and current models.The landing of the Philae module provided the cometary rendezvous mission Rosetta with an exceptional opportunity: that of studying in situ a cometary nucleus (from its surface to its internal structure), 67P/Churyumov-Gerasimenko (aka Churi). This is likely to shed light on these small celestial bodies that date back to the origins of the Solar System. The data collected by the lander's ten instruments on November 12-14, 2014 (during the 63 hours that followed Philae's separation from Rosetta) added to the observations carried out by the Rosetta orbiter1, while its bouncing touchdown on the comet was actually a source of extra information.Previously unreported organic compoundsTwenty-five minutes after Philae's initial contact with the cometary nucleus, COSAC (Cometary Sampling and Composition experiment) carried out a first chemical analysis in sniffing mode, that is, by examining particles that passively enter the instrument. These particles probably came from the cloud of dust raised by Philae's first contact with the ground. Sixteen compounds were identified, divided into six classes of organic molecules (alcohols, carbonyls, amines, nitriles, amides and isocyanates). Of these, four were detected for the first time on a comet (methyl isocyanate, acetone, propionaldehyde and acetamide).These particles are precursors of molecules important for life (sugars, amino acids, DNA bases, etc). However, the possible presence of these more complex compounds was not unambiguously confirmed in this first analysis. In addition, almost all the compounds detected are potential precursors, products, combinations or by-products of each other, which provides a glimpse of the chemical processes at work in a cometary nucleus, and even in the collapsing solar nebula in the very early Solar System.Agglomerates of pristine organic matterThe cameras of the CIVA experiment (Comet Infrared and Visible Analyser) reveal that the terrain in the vicinity of Philae's final landing site is dominated by dark clumps that are probably large grains made up of organic compounds. Since cometary material has hardly been altered since its origins, this means that, early in the Solar System's history, organic compounds had already clumped together in the form of grains, and not just as small molecules trapped in the ice as was previously thought. The introduction of such grains into planetary oceans could have led to the emergence of life.Varied terrains concealing a fairly homogeneous interiorCOSAC identified a large number of nitrogen compounds but no sulfur compounds, contrary to what the ROSINA instrument on board Rosetta had observed. This suggests that the chemical composition varies depending on the area sampled.In addition, it was possible to infer the mechanical properties of the surface from Philae's bouncing touchdown. The lander first touched down on the surface at a site dubbed Agilkia, and then bounced several times before reaching Abydos, the final landing site. Philae's trajectory and the data recorded by its instruments show that Agilkia is made up of granular materials at least twenty centimeters deep, whereas Abydos has a hard surface.On the other hand, the comet's interior appears to be more homogeneous than predicted by models. The radar experiment CONSERT (Comet Nucleus Sounding Experiment by Radio wave Transmission) provides, for the first time, an opportunity to investigate the internal structure of a cometary nucleus. The propagation time and amplitude of the signals that traveled through the upper part of the 'head' (the smaller of Churi's two lobes) show that this part of the nucleus is broadly homogeneous on a scale of tens of meters. The data also confirms that porosity is high (75 à 85%) and shows that the electrical properties of the dust are comparable to those of carbonaceous chondrites.A rugged surfaceThe CIVA-P (P for panorama) experiment, made up of seven microcameras, took a panoramic (360°) image of Philae's final landing site. It shows that fractures already observed on large scales by Rosetta are also present right down to millimeter scales. The fractures are caused by thermal stress, due to the large temperature differences on the comet as it travels around the Sun.Information about Philae's location and orientationThe panoramic image, in which a foot or an antenna can be seen in places, also revealed Philae's position. It rests in a hole about its own size, lying on its side (with only two feet out of three in contact with the ground), and surrounded by cliff walls that hinder its solar energy intake and its communications with Rosetta.With three periods of observation in conditions of direct visibility between the Rosetta orbiter and Philae, the CONSERT instrument was able to determine the area (150 meters by 15 meters) where Philae is located. This made it easier to reconstruct the robot's trajectory from the first touchdown site, Agilkia, to the final landing site, Abydos. Then, by using the signals that traveled through the comet's interior, CONSERT reduced the uncertainty surrounding Philae's location (on the edge of the region named Hatmehit) to a strip measuring 21 meters by 34 meters.Together with the other four articles published (which concern, for instance, Churi's magnetic and thermal properties), these first measurements taken on a comet's surface improve existing understanding of these small Solar System bodies.Story Source:The above post is reprinted from materials provided by CNRS. Note: Materials may be edited for content and length.Journal References:
    1. J.- P. Bibring, Y. Langevin, J. Carter, P. Eng, B. Gondet, L. Jorda, S. Le Mouelic, S. Mottola, C. Pilorget, F. Poulet, M. Vincendon. 67P/Churyumov-Gerasimenko surface properties as derived from CIVA panoramic images. Science, 2015; 349 (6247): aab0671 DOI: 10.1126/science.aab0671
    2. W. Kofman, A. Herique, Y. Barbin, J.-P. Barriot, V. Ciarletti, S. Clifford, P. Edenhofer, C. Elachi, C. Eyraud, J.-P. Goutail, E. Heggy, L. Jorda, J. Lasue, A.-C. Levasseur-Regourd, E. Nielsen, P. Pasquero, F. Preusker, P. Puget, D. Plettemeier, Y. Rogez, H. Sierks, C. Statz, H. Svedhem, I. Williams, S. Zine, J. Van Zyl. Properties of the 67P/Churyumov-Gerasimenko interior revealed by CONSERT radar. Science, 2015; 349 (6247): aab0639 DOI: 10.1126/science.aab0639
    3. F. Goesmann, H. Rosenbauer, J. H. Bredehoft, M. Cabane, P. Ehrenfreund, T. Gautier, C. Giri, H. Kruger, L. Le Roy, A. J. MacDermott, S. McKenna-Lawlor, U. J. Meierhenrich, G. M. M. Caro, F. Raulin, R. Roll, A. Steele, H. Steininger, R. Sternberg, C. Szopa, W. Thiemann, S. Ulamec. Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry. Science, 2015; 349 (6247): aab0689 DOI: 10.1126/science.aab0689
    4. J. Biele, S. Ulamec, M. Maibaum, R. Roll, L. Witte, E. Jurado, P. Munoz, W. Arnold, H.-U. Auster, C. Casas, C. Faber, C. Fantinati, F. Finke, H.-H. Fischer, K. Geurts, C. Guttler, P. Heinisch, A. Herique, S. Hviid, G. Kargl, M. Knapmeyer, J. Knollenberg, W. Kofman, N. Komle, E. Kuhrt, V. Lommatsch, S. Mottola, R. Pardo de Santayana, E. Remetean, F. Scholten, K. J. Seidensticker, H. Sierks, T. Spohn. The landing(s) of Philae and inferences about comet surface mechanical properties. Science, 2015; 349 (6247): aaa9816 DOI: 10.1126/science.aaa9816
      http://www.sciencedaily.com/releases/201...172518.htm    
      [Image: 150730172518_1_540x360.jpg]
      comet 67P/Churyumov-Gerasimenko, or 'Churi'. It has a 5 km diameter.Credit: ESAOrganic molecules Organic molecules on comets: 
    5. Philae's first results from Churi prove surprisingDate:July 30, 2015Source:CNRS
    6. Summary:Organic molecules never previously observed in comets, a relatively varied structure on the surface but a fairly homogeneous interior, organic compounds forming agglomerates rather than being dispersed in the ice: these are just some of first results provided by Philae on the surface of comet Churi. These in situ findings, which contain a wealth of completely new information, reveal several differences in comparison with previous observations of comets and current models.The nucleus of comet 67P/Churyumov-Gerasimenko, or 'Churi'. It has a 5 km diameter.Credit: ESAThe nucleus of never previously observed in comets, a relatively varied structure on the surface but a fairly homogeneous interior, organic compounds forming agglomerates rather than being dispersed in the ice: these are just some of first results provided by Philae on the surface of comet Churi. This work, carried out as part of ESA's Rosetta mission, involved researchers from the CNRS, Aix-Marseille Université, Université Joseph Fourier, Université Nice Sophia Antipolis, UPEC, UPMC, Université Paris-Sud, Université Toulouse III -- Paul Sabatier and UVSQ, with support from CNES. They are published on July 31, 2015 as part of a set of eight articles in the journal Science. These in situ findings, which contain a wealth of completely new information, reveal several differences in comparison with previous observations of comets and current models.The landing of the Philae module provided the cometary rendezvous mission Rosetta with an exceptional opportunity: that of studying in situ a cometary nucleus (from its surface to its internal structure), 67P/Churyumov-Gerasimenko (aka Churi). This is likely to shed light on these small celestial bodies that date back to the origins of the Solar System. The data collected by the lander's ten instruments on November 12-14, 2014 (during the 63 hours that followed Philae's separation from Rosetta) added to the observations carried out by the Rosetta orbiter1, while its bouncing touchdown on the comet was actually a source of extra information.Previously unreported organic compoundsTwenty-five minutes after Philae's initial contact with the cometary nucleus, COSAC (Cometary Sampling and Composition experiment) carried out a first chemical analysis in sniffing mode, that is, by examining particles that passively enter the instrument. These particles probably came from the cloud of dust raised by Philae's first contact with the ground. Sixteen compounds were identified, divided into six classes of organic molecules (alcohols, carbonyls, amines, nitriles, amides and isocyanates). Of these, four were detected for the first time on a comet (methyl isocyanate, acetone, propionaldehyde and acetamide).These particles are precursors of molecules important for life (sugars, amino acids, DNA bases, etc). However, the possible presence of these more complex compounds was not unambiguously confirmed in this first analysis. In addition, almost all the compounds detected are potential precursors, products, combinations or by-products of each other, which provides a glimpse of the chemical processes at work in a cometary nucleus, and even in the collapsing solar nebula in the very early Solar System.Agglomerates of pristine organic matterThe cameras of the CIVA experiment (Comet Infrared and Visible Analyser) reveal that the terrain in the vicinity of Philae's final landing site is dominated by dark clumps that are probably large grains made up of organic compounds. Since cometary material has hardly been altered since its origins, this means that, early in the Solar System's history, organic compounds had already clumped together in the form of grains, and not just as small molecules trapped in the ice as was previously thought. The introduction of such grains into planetary oceans could have led to the emergence of life.Varied terrains concealing a fairly homogeneous interiorCOSAC identified a large number of nitrogen compounds but no sulfur compounds, contrary to what the ROSINA instrument on board Rosetta had observed. This suggests that the chemical composition varies depending on the area sampled.In addition, it was possible to infer the mechanical properties of the surface from Philae's bouncing touchdown. The lander first touched down on the surface at a site dubbed Agilkia, and then bounced several times before reaching Abydos, the final landing site. Philae's trajectory and the data recorded by its instruments show that Agilkia is made up of granular materials at least twenty centimeters deep, whereas Abydos has a hard surface.On the other hand, the comet's interior appears to be more homogeneous than predicted by models. The radar experiment CONSERT (Comet Nucleus Sounding Experiment by Radio wave Transmission) provides, for the first time, an opportunity to investigate the internal structure of a cometary nucleus. The propagation time and amplitude of the signals that traveled through the upper part of the 'head' (the smaller of Churi's two lobes) show that this part of the nucleus is broadly homogeneous on a scale of tens of meters. The data also confirms that porosity is high (75 à 85%) and shows that the electrical properties of the dust are comparable to those of carbonaceous chondrites.A rugged surfaceThe CIVA-P (P for panorama) experiment, made up of seven microcameras, took a panoramic (360°) image of Philae's final landing site. It shows that fractures already observed on large scales by Rosetta are also present right down to millimeter scales. The fractures are caused by thermal stress, due to the large temperature differences on the comet as it travels around the Sun.Information about Philae's location and orientationThe panoramic image, in which a foot or an antenna can be seen in places, also revealed Philae's position. It rests in a hole about its own size, lying on its side (with only two feet out of three in contact with the ground), and surrounded by cliff walls that hinder its solar energy intake and its communications with Rosetta.With three periods of observation in conditions of direct visibility between the Rosetta orbiter and Philae, the CONSERT instrument was able to determine the area (150 meters by 15 meters) where Philae is located. This made it easier to reconstruct the robot's trajectory from the first touchdown site, Agilkia, to the final landing site, Abydos. Then, by using the signals that traveled through the comet's interior, CONSERT reduced the uncertainty surrounding Philae's location (on the edge of the region named Hatmehit) to a strip measuring 21 meters by 34 meters.Together with the other four articles published (which concern, for instance, Churi's magnetic and thermal properties), these first measurements taken on a comet's surface improve existing understanding of these small Solar System bodies.Story Source:The above post is reprinted from materials provided by CNRS. Note: Materials may be edited for content and length.Journal References:
    7. J.- P. Bibring, Y. Langevin, J. Carter, P. Eng, B. Gondet, L. Jorda, S. Le Mouelic, S. Mottola, C. Pilorget, F. Poulet, M. Vincendon. 67P/Churyumov-Gerasimenko surface properties as derived from CIVA panoramic images. Science, 2015; 349 (6247): aab0671 DOI: 10.1126/science.aab0671
    8. W. Kofman, A. Herique, Y. Barbin, J.-P. Barriot, V. Ciarletti, S. Clifford, P. Edenhofer, C. Elachi, C. Eyraud, J.-P. Goutail, E. Heggy, L. Jorda, J. Lasue, A.-C. Levasseur-Regourd, E. Nielsen, P. Pasquero, F. Preusker, P. Puget, D. Plettemeier, Y. Rogez, H. Sierks, C. Statz, H. Svedhem, I. Williams, S. Zine, J. Van Zyl. Properties of the 67P/Churyumov-Gerasimenko interior revealed by CONSERT radar. Science, 2015; 349 (6247): aab0639 DOI: 10.1126/science.aab0639
    9. F. Goesmann, H. Rosenbauer, J. H. Bredehoft, M. Cabane, P. Ehrenfreund, T. Gautier, C. Giri, H. Kruger, L. Le Roy, A. J. MacDermott, S. McKenna-Lawlor, U. J. Meierhenrich, G. M. M. Caro, F. Raulin, R. Roll, A. Steele, H. Steininger, R. Sternberg, C. Szopa, W. Thiemann, S. Ulamec. Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry. Science, 2015; 349 (6247): aab0689 DOI: 10.1126/science.aab0689
    10. J. Biele, S. Ulamec, M. Maibaum, R. Roll, L. Witte, E. Jurado, P. Munoz, W. Arnold, H.-U. Auster, C. Casas, C. Faber, C. Fantinati, F. Finke, H.-H. Fischer, K. Geurts, C. Guttler, P. Heinisch, A. Herique, S. Hviid, G. Kargl, M. Knapmeyer, J. Knollenberg, W. Kofman, N. Komle, E. Kuhrt, V. Lommatsch, S. Mottola, R. Pardo de Santayana, E. Remetean, F. Scholten, K. J. Seidensticker, H. Sierks, T. Spohn. The landing(s) of Philae and inferences about comet surface mechanical properties. Science, 2015; 349 (6247): aaa9816 DOI: 10.1126/science.aaa9816
  2. http://www.sciencedaily.com/releases/201...172518.htm

T-minus 12 days to perihelion, Rosetta's comet up close and in 3D

August 3, 2015 by Bob King, Universe Today

[Image: tminus12days.jpg]
We’ve never seen a comet as close as this. Taken shortly before touchdown by the Philae lander on November 12, 2014, you’re looking across a scene just 32 feet from side to side (9.7-meters) or about the size of a living room. Part of the lander is visible at upper right. Credit: ESA/Rosetta/Philae/ROLIS/DLR

With just 12 days before Comet 67P/Churyumov-Gerasimenko reaches perihelion, we get a look at recent images and results released by the European Space Agency from the Philae lander along with spectacular 3D photos from Rosetta's high resolution camera.

Remarkably, some 80% of the first science sequence was completed in the 64 hours before Philae fell into hibernation. Although unintentional, the failed landing attempt led to the unexpected bonus of getting data from two collection sites—the planned touchdown at Agilkia and its current precarious location at Abydos.
After first touching down, Philae was able to use its gas-sniffing Ptolemy and COSAC instruments to determine the makeup of the comet's atmosphere and surface materials. COSAC analyzed samples that entered tubes at the bottom of the lander and found ice-poor dust grains that were rich in organic compounds containing carbon and nitrogen. It found 16 in all including methyl isocyanate, acetone, propionaldehyde and acetamide that had never been seen in comets before.
While you and I may not be familiar with some of these organics, their complexity hints that even in the deep cold and radiation-saturated no man's land of outer space, a rich assortment of organic materials can evolve. Colliding with Earth during its early history, comets may have delivered chemicals essential for the evolution of life.


[Image: tminus12days.gif]Slow animation of images taken by Philae’s Rosetta Lander Imaging System, ROLIS, trace the lander’s descent to the first landing site, Agilkia, on Comet 67P/Churyumov–Gerasimenko on November 12, 2014. Credits: ESA/Rosetta/Philae/ROLIS/DLR
Ptolemy sampled the atmosphere entering tubes at the top of the lander and identified water vapor, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing organic compounds, including formaldehyde. Some of these juicy organic delights have long been thought to have played a role in life's origins. Formaldehyde reacts with other commonly available materials to form complex sugars like ribose which forms the backbone of RNA and is related to the sugar deoxyribose, the "D" in DNA.
ROLIS (Rosetta Lander Imaging System) images taken shortly before the first touchdown revealed a surface of 3-foot-wide (meter-size) irregular-shaped blocks and coarse "soil" or regolith covered in "pebbles" 4-20 inches (10–50 cm) across as well as a mix of smaller debris.
Agilkia's regolith, the name given to the rocky soil of other planets, moons, comets and asteroids, is thought to extend to a depth of about 6 feet (2 meters) in places, but seems to be free from fine-grained dust deposits at the resolution of the images. The 16-foot-high boulder in the photo above has been heavily fractured by some type of erosional process, possibly a heating and cooling cycle that vaporized a portion of its ice. Dust from elsewhere on the comet has been transported to the boulder's base. This appears to happen over much of 67P/C-G as jets shoot gas and dust into the coma, some of which then settles out across the comet's surface.


Another suite of instruments called MUPUS used a penetrating "hammer" to reveal a thin layer of dust about an inch thick (~ 3 cm) overlying a much harder, compacted mixture of dust and ice at Abydos. The thermal sensor took the comet's daily temperature which varies from a high around –229° F (–145ºC) to a nighttime low of about –292° F (–180ºC), in sync with the comet's 12.4 hour day. The rate at which the temperature rises and falls also indicates a thin layer of dust rests atop a compacted dust-ice crust.

[Image: 1-tminus12days.jpg]
This 3D image focuses on the largest boulder seen in the image captured 221 feet (67.4 m) above Comet 67P/Churyumov–Gerasimenko looks best in a pair of red-blue 3D glasses. Many fractures, along with a tapered ‘tail’ of debris and excavated ‘moat’ around the 5 m-high boulder, are plain to see. Credit: ESA/Rosetta/Philae/ROLIS/DLR
CONSERT, which passed radio waves through the nucleus between the lander and the orbiter, showed that the small lobe of the comet is a very loosely compacted mixture of dust and ice with a porosity of 75-85%, about that of lightly compacted snow. CONSERT was also used to help triangulate Philae's location on the surface, nailing it down to an area just 69 x 112 feet ( 21 x 34 m) wide.
In fewer than two weeks, the comet will reach perihelion, its closest approach to the Sun at 116 million miles (186 million km), and the time when it will be most active. Rosetta will continue to monitor 67P C-G from a safe distance to lessen the chance an errant chunk of comet ice or dust might damage its instruments. Otherwise it's business as usual. Activity will gradually decline after perihelion with Rosetta providing a ringside seat throughout. The best time for viewing the comet from Earth will be mid-month when the Moon is out of the morning sky. Watch for an article with maps and directions soon.

[Image: 2-tminus12days.jpg]
Philae used its thermal sensor to measure daily highs and lows on the comet (top graph). The bottom graph shows time vs. depth when Philae used its penetrator to hammer into the soil. Credit: Spacecraft graphic: ESA/ATG medialab; data from Spohn et al (2015)
"With perihelion fast approaching, we are busy monitoring the comet's activity from a safe distance and looking for any changes in the surface features, and we hope that Philae will be able to send us complementary reports from its location on the surface," said Philae lander manager Stephan Ulamec.
More about Philae's findings can be found in the July 31 issue of Science. Before signing off, here are a few detailed, 3D images made with the high-resolution OSIRIS camera on Rosetta. Once you don a pair of red-blue glasses, click the photos for the high-res versions and get your mind blown.


[Image: 3-tminus12days.jpg]
Based on the most recent calculations using CONSERT data and detailed comet shape models, Philae’s location has been revised to an area covering 69 x 112 feet (21 x 34 m). The best fit area is marked in red, a good fit is marked in yellow, with areas on the white strip corresponding to previous estimates now discounted. Credit: ESA/Rosetta/Philae/CONSERT

[Image: 4-tminus12days.jpg]
The orbit of Comet 67P/Churyumov–Gerasimenko and its approximate location around perihelion, the closest the comet gets to the Sun. The positions of the planets are correct for August 13, 2015. The comet will pass closest to Earth in February 2016 at 135.6 million miles but will be brightest this month right around perihelion. Credit: ESA

[Image: 5-tminus12days.jpg]
Mosaic of two images showing an oblique view of the Atum region and its contact with Apis, the flat region in the foreground. This region is rough and pitted, with very few boulders.Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

[Image: 6-tminus12days.jpg]
Image highlighting an alcove structure at the Hathor-Anuket boundary on the comet’s small lobe. The layering seen in the alcove could be indicative of the internal structure of the comet. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

[Image: 7-tminus12days.jpg]

Explore further: OSIRIS spots Philae drifting across the comet
Source:: Universe Today


Read more at: http://phys.org/news/2015-08-t-minus-day...t.html#jCp
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
A Direct Hit from the Improvisphere.
Rite here on the neurons.

[Image: tminus12days.gif]
Frame of reference begins @ 3.3 meters / pixel LilD
Quote:Before signing off, here are a few detailed, 3D images made with the high-resolution OSIRIS camera on Rosetta. Once you don a pair of red-blue glasses, click the photos for the high-res versions and get your mind blown.

'Blowing my mind':


[Image: 20273985111_6c69955b40.jpg]
"Itz physics, man." -John Wilkes Boothe
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
...

Thanks for posting all that info.


Quote:"The hoped-for witness to the formation of the solar system is suffering, 
as it were, 
from amnesia."   Comet ---> is in the middle ... Mission Scientist --->  Gangup <--- Mission Scientist


 Vastly lame excuse, ... lame like a peg legged monkey with crutches.
They actually expected that the comet would be a pristine copy of itself from 4.5 billiion years ago.
Idiots.



Quote:The solidification of the material indicates processes, 
which have sustainably changed the comet or are still changing it"


"Comets are tough nuts to crack" becasue they have a hard crusty shell ... Phil Whip

This statement here is a solid summation about all the current missions, ... Ceres and Pluto,
and the science that preceded those missions.


Quote:"Like almost every time that space probes   Ninja   Ninja   Ninja

examine  Sheep an as yet unknown body   Console

everything was different to expected   Doh

Nature surprises us repeatedly and leaves us with more questions than we had before." 


... and then the idiots Shemp  Whip
 basically had to relegate themselves to the inglorious and ignominious conclusion:

"The comet has had 4.5 billion years to change."

No Shit Sherlock .... or Not Sure, Shitlock?

.....

 
Reply
Comet 67P, robot lab Philae's alien host, nears Sun

August 10, 2015 by Mariette Le Roux

[Image: 6-anartistsimp.jpg]
An artist'’s impression of Rosetta’s lander Philae (back view) on the surface of comet 67P/Churyumov-Gerasimenko


A comet streaking through space with a European robot lab riding piggyback will skirt the Sun this week, setting another landmark in an extraordinary quest to unravel the origins of life on Earth.



Scientists hope the heat of perihelion—when the comet comes closest to the Sun in its orbit—will cause the enigmatic traveller to shed more of its icy crust.

If so, it could spew out pristine particles left from the Solar System's birth 4.6 billion years ago, they believe.

And if Comet 67P/Churyumov-Gerasimenko undergoes this dramatic change, Europe's Rosetta spacecraft will be orbiting nearby, ready to pounce on any clues of how our star system came into being.

"This is the time most of the action happens," said European Space Agency (ESA) expert Mark McCaughrean of the weeks-long peak of comet activity.



The ancient celestial voyager will reach its closest point to our star—some 186 million kilometres (116 million miles)—at about 0200 GMT on Thursday, before embarking on another 6.5-year egg-shaped orbit.
Things have been heating up for weeks, with gas and dust blasting off the comet's surface as solar heat transforms its frozen crust into a space tempest.
This is "the greatest opportunity to catch material and analyse it if you're looking for rare species of molecules," especially organic ones, McCaughrean told AFP.
"We want to look at the more pristine material that might come out" from beneath the layer of icy dust stripped from the surface.


Most exciting would be if the duck-shaped  youareaduck comet's "neck"—which hosts a 500-metre (1,640-foot) crack—were to break in two to reveal the raw insides.
"That's really the Holy Grail... to see the interior of the comet," said McCaughrean, though most scientists believe a breakup is unlikely this time around.


Compromise: Safety vs science


[Image: theprogresso.jpg][/url]


The progress of the 'Chury' comet and the Philae as they approach they closes point to the Sun



In any scenario, ground teams working on the 20-year-old Rosetta mission will likely have to wait weeks, if not months, to analyse new data.

Quote:For one thing, there has been no word from Philae, their eyes on the ground, since July 9, and its status is unknown.

Right now, 67P with its precious cargo is hurtling through space at 34.17 km per second.
Rosetta has had to move farther away to avoid the confounding effects of the dust storm on its star-tracking navigation system.

The spacecraft now orbits at some 200-300 km from the comet, compared to less than 10 km at its closest in October last year.
"If we were right next to it, bathing in the material, they (scientists) would be super happy," said McCaughrean—but with a high risk of losing Rosetta.
"You have to do a compromise between spacecraft safety and getting as close as possible," added Philae project manager Stephan Ulamec of German space agency DLR.
Rosetta's instruments can still catch particles, but these are less sensitive than Philae's.
Once the most violent outgassing is over, Rosetta will move closer again and seek to re-establish contact with Philae, hoping that somehow the little lab has been going about its scientific business all along.

[Image: acloseupimag.jpg]

A close-up image of the most active pit, known as Seth 01, observed on the surface of the comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft


But even if Philae has gone permanently silent, scientists can learn a lot from before-and-after images, gas samples and other measurements taken by Rosetta itself.
Water mystery
Some experts believe comets smashed into our infant planet, providing it with precious water and the chemical building blocks for life.
The Rosetta mission has already shown that at least as far as water is concerned, this is not the complete picture.
Water on 67P is of a slightly different chemical composition—a different "flavour" than Earth's.

[Image: thephilaelan.jpg]
The Philae lander, as seen through Rosetta'’s OSIRIS narrow-angle camera in November 2014


Rosetta deposited washing machine-sized Philae on the comet on November 12 last year after a 10-year, seven-billion-kilometre trek.
The landing was rough, and the robot tumbled into a ditch shadowed from the Sun's battery-recharging rays. After three days of comet sniffing and prodding, its onboard power ran out, and Philae went into hibernation on November 15.
But as 67P drew closer to the Sun, it recharged and woke up on June 13, only to fall silent again less than a month later.
Just in case it is awake, ground controllers have sent "blind commands" for the lab to activate a few basic experiments during the perihelion period.
Europe's comet-chasing Rosetta mission: timeline
Following is a timeline of Europe's Rosetta mission, which will reach a milestone Thursday when its target, Comet 67P/Churyumov-Gerasimenko,reaches perihelion—the closest point to the Sun in a 6.5-year orbit.
- March 2, 2004:
Rosetta, carrying a robot lab called Philae, is launched by Ariane 5 rocket from the European Space Agency's base in Kourou, French Guiana.
- March 2005:
Rosetta flies past Earth, using the planet's gravity as a slingshot to boost speed. It zips by Mars in 2007 and twice more by Earth, in 2007 and 2009, to accelerate further.
- June 2011 to January 20, 2014:
At its maximum distance—about 800 million kilometers or 500 million miles—from the Sun and a billion km from home, Rosetta hibernates to conserve energy.
- August 6, 2014:
Rosetta arrives at comet 67P, and goes into orbit. It has 11 onboard instruments: cameras, radar, microwave, infrared and other sensors to analyse the comet surface and gases escaping from it.
- November 12, 2014:
Rosetta sends down Philae, a 100-kilogramme (220-pound) lab equipped with 10 instruments. After bouncing several times, Philae ends in a ditch, shadowed from the Sun's battery-replenishing rays.
- November 15, 2014:
Philae's stored battery power runs out after about 60 hours of work. It sends home reams of data before going into standby mode.
- June 13:
As 67P nears the Sun, Philae's batteries are recharged, it emerges from hibernation and sends home a two-minute message.
- July 9:
Philae goes into "silent mode" after eight intermittent communications with Earth.
Looking ahead
- August 13: 67P to come within 186 million km of the Sun, its closest distance to our star.
- September 2016: Projected end of the mission, with Rosetta, now replete of fuel, to be reunited with Philae on the comet surface.  Luv

[url=http://phys.org/news/2015-08-comet-67p-robot-lab-philae.html#][Image: 1x1.gif]
 Explore further: Europe's Rosetta craft swoops for close look at comet


Read more at: http://phys.org/news/2015-08-comet-67p-robot-lab-philae.html#jCp
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
COMET’S FIREWORK DISPLAY AHEAD OF PERIHELION

[Image: PIA-19867-16.gif]

11 August 2015
In the approach to perihelion over the past few weeks, Rosetta has been witnessing growing activity from Comet 67P/Churyumov–Gerasimenko, with one dramatic outburst event proving so powerful that it even pushed away the incoming solar wind.


[Image: Outburst_in_action_large.jpg]
Outburst in action

The comet reaches perihelion on Thursday, the moment in its 6.5-year orbit when it is closest to the Sun. In recent months, the increasing solar energy has been warming the comet’s frozen ices, turning them to gas, which pours out into space, dragging dust along with it.
The period around perihelion is scientifically very important, as the intensity of the sunlight increases and parts of the comet previously cast in years of darkness are flooded with sunlight.
Although the comet’s general activity is expected to peak in the weeks following perihelion, much as the hottest days of summer usually come after the longest days, sudden and unpredictable outbursts can occur at any time – as already seen earlier in the mission.

On 29 July, Rosetta observed the most dramatic outburst yet, registered by several of its instruments from their vantage point 186 km from the comet. They imaged the outburst erupting from the nucleus, witnessed a change in the structure and composition of the gaseous coma environment surrounding Rosetta, and detected increased levels of dust impacts.

[Image: Discovery_of_diamagnetic_cavity_medium.jpg]
Discovery of diamagnetic cavity


Perhaps most surprisingly, Rosetta found that the outburst had pushed away the solar wind magnetic field from around the nucleus.

A sequence of images taken by Rosetta’s scientific camera OSIRIS show the sudden onset of a well-defined jet-like feature emerging from the side of the comet’s neck, in the Anuket region. It was first seen in an image taken at 13:24 GMT, but not in an image taken 18 minutes earlier, and has faded significantly in an image captured 18 minutes later. The camera team estimates the material in the jet to be travelling at 10 m/s at least, and perhaps much faster.
“This is the brightest jet we’ve seen so far,” comments Carsten Güttler, OSIRIS team member at the Max Planck Institute for Solar System Research in Göttingen, Germany.
“Usually, the jets are quite faint compared to the nucleus and we need to stretch the contrast of the images to make them visible – but this one is brighter than the nucleus.”


Soon afterwards, the comet pressure sensor of ROSINA detected clear indications of changes in the structure of the coma, while its mass spectrometer recorded changes in the composition of outpouring gases.

For example, compared to measurements made two days earlier, the amount of carbon dioxide increased by a factor of two, methane by four, and hydrogen sulphide by seven, while the amount of water stayed almost constant.



[Image: Gas_changes_during_29_July_outburst_medium.jpg]

Gas changes during 29 July outburst




“This first ‘quick look’ at our measurements after the outburst is fascinating,” says Kathrin Altwegg, ROSINA principal investigator at the University of Bern. “We also see hints of heavy organic material after the outburst that might be related to the ejected dust.


“But while it is tempting to think that we are detecting material that may have been freed from beneath the comet's surface, it is too early to say for certain that this is the case.”

Meanwhile, about 14 hours after the outburst, GIADA was detecting dust hits at rates of 30 per day, compared with just 1–3 per day earlier in July. A peak of 70 hits was recorded in one 4-hour period on 1 August, indicating that the outburst continued to have a significant effect on the dust environment for the following few days.
“It was not only the abundance of the particles, but also their speeds measured by GIADA that told us something ‘different’ was happening: the average particle speed increased from 8 m/s to about 20 m/s, with peaks at 30 m/s – it was quite a dust party!” says Alessandra Rotundi, principal investigator at the ‘Parthenope’ University of Naples, Italy.



[Image: 29_July_outburst_context_medium.jpg]
29 July outburst context(a crick in space-duck's neck)


Perhaps the most striking result is that the outburst was so intense that it actually managed to push the solar wind away from the nucleus for a few minutes – a unique observation made by the Rosetta Plasma Consortium’s magnetometer.


The solar wind is the constant stream of electrically charged particles that flows out from the Sun, carrying its magnetic field out into the Solar System. Earlier measurements made by Rosetta and Philae had already shown that thecomet is not magnetised,  so the only source for the magnetic field measured around it is the solar wind.
But it doesn’t flow past unimpeded. Because the comet is spewing out gas, the incoming solar wind is slowed to a standstill where it encounters that gas and a pressure balance is reached.
“The solar wind magnetic field starts to pile up, like a traffic jam, and eventually stops moving towards the comet nucleus, creating a magnetic field-free region on the Sun-facing side of the comet called a ‘diamagnetic cavity’,” explains Charlotte Götz, magnetometer team member at the Institute for Geophysics and extraterrestrial Physics in Braunschweig, Germany.
Diamagnetic cavities provide fundamental information on how a comet interacts with the solar wind, but the only previous detection of one associated with a comet was made at about 4000 km from Comet Halley as ESA’s Giotto flew past in 1986. 
Rosetta’s comet is much less active than Halley, so scientists expected to find a much smaller cavity around it, up to a few tens of kilometres at most, and prior to 29 July, had not observed any sign of one.
But, following the outburst on that day, the magnetometer detected a diamagnetic cavity extending out at least 186 km from the nucleus. This was likely created by the outburst of gas, which increased the neutral gas flux in the comet’s coma, forcing the solar wind to ‘stop’ further away from the comet and thus pushing the cavity boundary outwards beyond where Rosetta was flying at the time.
"Finding a magnetic field-free region anyway in the Solar System is really hard, but here we've had it served to us on a silver platter – this is a really exciting result for us," adds Charlotte.
“We’ve been moving Rosetta out to distances of up to 300 km in recent weeks to avoid problems with navigation caused by dust, and we had considered that the diamagnetic cavity was out of our grasp for the time being. But it seems that the comet has helped us by bringing the cavity to Rosetta,” says Matt Taylor, Rosetta Project Scientist.
“This is a fantastic multi-instrument event which will take time to analyse, but highlights the exciting times we’re experiencing at the comet in this ‘hot’ perihelion phase.”


Notes for Editors:
A Google+ Hangout celebrating a year at the comet and perihelion is scheduled for 13:00–15:00 GMT (15:00–17:00 CEST) on 13 August. Watch here. (Ask questions in advance on the G+ event page or via Twitter using #AskRosetta).
Learn more about perihelion in our FAQ here.
About Rosetta
Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is contributed by a consortium led by DLR, MPS, CNES and ASI.


http://www.esa.int/Our_Activities/Space_...perihelion


Incomming... Outgassing!!!
[Image: Comet_jet_awakens_node_full_image_2.gif]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Awesome pictures !
Never invite a Yoda to a frog leg dinner.
Go ahead invite Yoda to a Frog leg dinner
Reply
@ Perihelion!!!  LilD

(08-12-2015, 09:44 PM)Wook Wrote: Awesome pictures !

New model describes cognitive decision making as the collapse of a quantum superstate

August 12, 2015 by Christopher Packham

[Image: 55cb099ad4783.jpg]
Diagram of a state representation of a Markov and a quantum random walk model. In the Markov model, evidence (shaded state) evolves over time by moving from state to state, occupying one definite evidence level at any given time. In the quantum model the decision-maker is in an indefinite evidence state, with each evidence level having a probability amplitude (shadings) at each point in time. Credit: © 2015 PNAS; doi:10.1073/pnas.1500688112

Read more at: http://phys.org/news/2015-08-cognitive-d...e.html#jCp

This is not an "Improv"  wook.

Itza Duck's Waddle vieled in metaphor as poetic twaddle that this thread knows as a Quantum Random Walk / Full Throttle.


[Image: Comet_jet_awakens_node_full_image_2.gif]
Perhaps most surprisingly, Rosetta found that the outburst had pushed(expanded the wave Hi )away the solar wind magnetic field from around the nucleus.

Itza QRW Eh Mayito???

Philae... Jump Up^


Quote:Land? / Not Land.

Alive? / Not Alive.

Up^ / Not Up^
 
This thread has uncertainly been a " perihelion cliff "-hanger so far...

What will become of Shroedinger's Philae???


Preparing for perihelion


Posted on 13/07/2015 by emily

Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Research shows that comet impacts may have led to life on Earth—and perhaps elsewhere
August 18, 2015

[Image: comet.jpg]
The momentum of light (along with the solar wind) creates the tails of comets by pushing material off the comets. Credit: European Southern Observatory
Comet impact on Earth are synonymous with great extinctions, but now research presented at the Goldschmidt geochemistry conference in Prague shows that early comet impact would have become a driving force to cause substantial synthesis of peptides - the first building blocks of life. This may have implications for the genesis of life on other worlds.

Dr Haruna Sugahara, from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in Yokahama, and Dr Koichi Mimura, from Nagoya University performed a series of experiments to mimic the conditions of comet impacts on the Early Earth at the time when life first appeared, around 4 billion years ago.
They took frozen mixtures of amino acid, water ice and silicate (forsterite) at cryogenic condition (77 K), and used a propellant gun to simulate the shock of a comet impact. After anyalysing the post-impact mixture with gas chromatography, they found that some of the amino acids had joined into short peptides of up to 3 units long (tripeptides).
Based on the experimental data, the researchers were able to estimate that the amount of peptides produced would be around the same as had been thought to be produced by normal terrestrial processes (such as lighting storms or hydration and dehydration cycles).
According to Haruna Sugahara:


"Our experiment showed that the cold conditions of comets at the time of the impacts were key to this synthesis, as the type of peptide formed this way are more likely to evolve to longer peptides.
This finding indicates that comet impacts almost certainly played an important role in delivering the seeds of life to the early Earth. It also opens the likelihood that we will have seen similar chemical evolution in other extraterrestrial bodies, starting with cometary-derived peptides.
Within our own solar system the icy satellites of Jupiter and Saturn, such as Europa and Enceladus are likely to have undergone a similar comet bombardment. Indeed, the NASA stardust mission has shown the presence of the amino acid glycine in comets.
The production of short peptides is the key step in the chemical evolution of complex molecules. Once the process is kick-started, then much less energy is needed to make longer chain peptides in a terrestrial, aquatic environment.
Comet impacts are normally associated with mass extinction on Earth, but this works shows that they probably helped kick-start the whole process of life in the first place".
Commenting, Professor Mark Burchell (University of Kent, UK) said: "This is a new piece of work which adds significantly to the exciting field of the origin of complex molecules on the Earth. It has long been known that ices under shock can generate and break bonds in complex organics. The detection of amino acids on comet 81P/Wild2 by the NASA Stardust mission in the last decade, and the now regular exciting news from the Rosetta mission to comet 67P/Churyumuv-Gerasimenko indicates that comets are a rich source of materials. Two key parts to this story are how complex molecules are initially generated on comets and then how they survive/evolve when the comet hits a planet like the Earth. Both of these steps can involve shocks which deliver energy to the icy body. For example, Zita Martins and colleagues recently showed how complex organic compounds can be synthesised on icy bodies via shocks. Now, building on earlier work, Dr Sughara and Dr Mimura have shown how amino acids on icy bodies can be turned into short peptide sequences, another key step along the path to life".
[Image: 1x1.gif] Explore further: Scientists discover cosmic factory for making building blocks of life
More information: Glycine oligomerization up to triglycine by shock experiments simulating comet impacts
H. SUGAHARA1* AND K. MIMURA2 1Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, 237-0061, Japan (*correspondence) 2Nagoya University, Nagoya, 464-8601, Japan
ABSTRACT
Abiotic peptide synthesis is one of key steps in prebiotic chemistry. Peptides are building block of proteins and also play a role as a catalyst to form other biomolecules (e.g., [1]). Although varieties of mechanisms for abiotic peptide synthesis in terrestrial environments have been proposed, extraterrestrial contribution, that is, cometary and asteroidal impacts has attracted little attention. Considering that the frequency of the extraterrestrial impacts on the early Earth was greater than present day and comets and chondrites contain amino acids (e.g., [2] [3]), extraterrestrial impacts could be a candidate for peptide synthesis.
In order to examine the feasibility of abiotic peptide synthesis by comet impacts, we conducted shock experiments on frozen mixtures of amino acid, water ice and silicate (forsterite) at cryogenic condition (77 K). In the experiments, the frozen amino acid mixture was sealed into a capsule and put into a container filled with liquid nitrogen to be kept at 77 K during the shock experiments. A vertical propellant gun was used to give impact shock.
The amounts of remaining amino acid and synthesized peptides in the recovered shocked samples were analyzed with gas chromatographs after the extraction and the derivatization. The results showed that amino acid was oligomerized into peptides up to tripeptide by impact shock. Furthermore, the yield of linear dipeptide was much higher than that of cyclic diketopiperazine. These results were contrasting to the results of shock experiments at room temperature, in which they resulted in the formation of comparable amount of cyclic peptides to linear peptides [4].
These results indicate that the cryogenic condition at impact shock is a key for the formation of linear peptide. Linear peptides are more useful than cyclic peptides for further elongation of peptide chain. Thus, comet impacts might have played an important role in chemical evolution by delivering linear peptides to the early Earth. [1] Barbier et al. (1993) J. Mol. Evol. 37, 554-558. [2] Elsila et al. (2009) Meteorit. Planet. Sci. 44, 1323-1330. [3] Burton et al. (2012) Chem. Soc. Rev. 41, 5459-5472. [4] Blank et al. (2001) Orig. Life Evol. Biosph. 31, 15-51
Provided by: European Association of Geochemistry


Read more at: http://phys.org/news/2015-08-comet-impac...d.html#jCp




[Image: 55cb099ad4783.jpg]QRW:


Wickramasinghe will have his day.
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Wayyyyyyyyyyyyyyyyy too cool!!!   Fly Hi  Bye

Boulder flying by comet

[Image: Boulder_flying_by_comet.gif]

Details
[Image: arw_red_on.gif]
  • Title Boulder flying by comet
  • Released 13/08/2015 4:30 pm
  • Copyright ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
  • Description
    This sequence of images, taken with Rosetta’s OSIRIS narrow-angle camera on 30 July 2015, show a boulder-sized object close to the nucleus of Comet 67P/Churyumov–Gerasimenko. 
    The images were captured on 30 July 2015, about 185 km from the comet. The object measures between one and 50 m across; however, the exact size cannot be determined as it depends on its distance to the spacecraft, which cannot be inferred from these images.
  • Id 345482



[*]Posted on 03/08/2015 by Emily
[*]
First release of Rosetta comet phase data from four orbiter instruments


ESA’s Rosetta downlink and archive teams are very happy to announce the release today of the first wave of Rosetta instrument data from the “comet pre-landing phase” via the Planetary Science Archive. Data from four instruments are included in this release: COSIMA, OSIRIS, ROSINA, and RPC-MAG.
[Image: Rosetta_s_instruments_white_background-350x247.jpg]
Rosetta's instruments. Credit: ESA/ATG medialab
After Rosetta woke up from 31 months hibernation in January 2014, its scientific instruments were turned back on and checked out before being used to study Comet 67P/Churyumov-Gerasimenko during the approach, rendezvous, and escort phases.
As agreed between ESA and the funding bodies responsible for Rosetta’s instruments, their data are initially made available to the corresponding scientific teams for first analysis, with a significant number of Rosetta papers published based on these data, as described in previous blog posts.
After a nominal period of 6 months, the scientific data themselves are to be delivered to ESA to be placed in the public domain via the Planetary Science Archive (PSA) for use by all scientists and the wider public. In practice, it was agreed to deliver data to ESA for release in blocks, and the first of those blocks was defined as the ‘pre-landing phase’, i.e. covering the period from January 2014 to just after Philae’s landing on the comet in mid-November 2014.
This led to a date of 19 May for the instrument teams to deliver the data from that phase to ESA, following which, a very significant effort had to be made by the ESA team to process the datasets of the many instruments involved and prepare them for release.
What did this processing entail? Firstly, the data and the associated metadata had to be checked for completeness and for compliance with standard formats to ensure that they can be downloaded and analysed by other scientists in a transparent manner.
This involved interactions between all of the instrument teams, the ESAC-based downlink and archive teams, and the Planetary Data System (PDS – Small Bodies Node) team located in the US to ensure the data format and contents complied with the PDS standards.
These complex checks and interactions have taken quite some time, in part because this was the first major data delivery from the comet phase to ESA from the whole instrument suite. For some instruments, the datasets are vast, with up to 8 months of scientific measurements, pushing processing systems to the limit. In the majority of cases, this procedure has necessitated updates to an instrument’s data pipeline, resulting in the need for the data to be re-processed, re-delivered, and checked once more.
Today sees the first release of pre-landing phase data from four of Rosetta’s instruments, representative of the wide scientific scope of the orbiter. COSIMA collects and analyses dust grains around the comet; OSIRIS uses its Narrow and Wide Angle Cameras to take multi-wavelength visible and near-infrared images of the nucleus, activity rising from its surface, and the immediate coma; ROSINA has two mass spectrometers to sniff and analyse the gases and RPC-MAG studies the magnetic field in the environment of the comet,
The data being released are described in more detail below:
COSIMA (COmetary Secondary Ion Mass Analyser):
This dataset includes images of dust particles collected in the environment of Comet 67P/C-G from the nucleus approach phase until 19 November 2014, along with secondary ion mass spectra for some of those particles.
OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System)
This dataset covers the first part of the pre-landing phase from 20 March to 12 June 2014, comprising four sets each for the Narrow Angle Camera and the Wide Angle Camera, and consisting of 2203 images in total. It contains the early light curve observations used to make a precise determination of rotation period and orientation of the rotation axis of Comet 67P/C-G. It also includes the outburst observed in April/May 2014 and the development of the dusty coma around the cometary nucleus. The data were processed with the new, re-developed OSIRIS calibration pipeline including recent updates from the in-flight calibration campaigns.
ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis)
This dataset covers the period March to November 2014, and contains 100 Gbytes of data consisting of 685,234 tables and 1.3 billion rows. These are currently “level 2” data, meaning more or less as received from the spacecraft, followed by decompression and the addition of metadata including the distance to the comet, direction of the Sun, and the spacecraft pointing. Future releases will be at a higher, more directly usable level containing mass spectra with physical units (e.g. detected particles vs. mass); further work is necessary to ensure that this is achieved in a consistent manner.
RPC-MAG (Rosetta’s Plasma Consortium MAGnetometer)
This dataset contain time series of the magnetic field measurements made in situ on Rosetta. RPC-MAG comprises two tri-axial fluxgate magnetometers that are able to register the three components of the magnetic field vector at a maximum sampling rate of 20 Hz. Observations have been made quasi permanently since May 2014, and the dataset covers from then until 19 November. Further processing of the data is on-going in order to reduce contamination due to changing spacecraft bias fields.
Access to these instrument datasets can be made here.
OSIRIS images added to Archive Image Browser
In addition to the data being released today to the PSA, the downlink and archive team is pleased to release an update of the Archive Image Browser. As well as images from Rosetta’s NAVCAM, this “easy access tool” now includes OSIRIS images from the Earth, Mars, and asteroid fly-bys that occurred between 2005 and 2010 en-route to the comet, and a “first processed” version of the images from today’s pre-landing phase release. Further processing of the OSIRIS pre-landing images in the image browser will be performed in the mid-late August timeframe.
[Image: ESA_ArchiveBrowser_OSIRIS-1024x411.png]
Screenshot from ESA's Archive Image Browser showing OSIRIS cruise phase albums
Upcoming data deliveries
While it has taken quite some time to process and release all the pre-landing datasets delivered, we anticipate that future processing will be more efficient and timely. The Philae lander instrument teams have delivered the data that formed the basis of the seven papers published in Science last week, and the next comet phase data delivery from the orbiter instrument teams is planned for mid-September (covering 19-Nov to 10-Mar 2015). With the corrected pipelines now producing data formats consistent with the archive standards, we expect to be able to archive and release those data more rapidly thereafter. The aim is to have the current Rosetta and Philae datasets released by mid-September.
It is important to realise that even after today’s first release, this process remains a work-in-progress. As more is learned about the calibration of the various instruments from in-flight measurements, and as feedback is received from the instrument teams and external users, these data may be re-processed and released again into the archives. This is standard practice and ensures that the data found in the archives always reflect the current best understanding of the complex instruments that produced them. A case in point is the current OSIRIS dataset, where issues still remain with their pipeline: a second version will be released to the PSA by September to correct for such problems.
Beyond the formal validation steps, a scientific review of these Rosetta pre-landing data is scheduled to take place at the beginning of 2016. This review will assess the scientific usefulness of the data and may lead to updates being made to various instrument datasets to incorporate proposed improvements in this regard.
At a higher level, the goal of the activities described in this post is to ensure that the products entering the archive are well documented and remains compatible with changing computer hard- and software systems, so that they can be used far into the future,
For example, we can now retrieve archival data from Giotto’s mission to Comet Halley in 1986 and re-analyse it with Rosetta’s discoveries in mind. We are still finding valuable and surprising information in these old data, which in turn enhances the science return from Rosetta. But the prerequisite for this is to adhere to very strict rules: a difficult task but worthwhile in the long run to maximise the legacy of the Rosetta mission.


http://blogs.esa.int/rosetta/2015/08/03/...struments/
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
...


the boulder Fly  Naughty Bye

Quote:The object measures between one and 50 m across ...

the exact size cannot be determined as it depends on its distance to the spacecraft


Yet when this happens on SOHO imaging of the sun,
and anomalies pass by or through the camera field of vision,
Phil the Pill Plait Whip
is the first to call it all:
dust particles --- no matter what they look like ... 
or
the SOHO team calls everything else ... cosmic rays ... 

That boulder in the image isn't just one meter monkey foo Nonono ... it is the size of a dump truck ...

great image!

...
Reply
More Comet-Wine?


[Image: 20942855879_49f209a8db_o.jpg]



[Image: 20941515520_90b3782c75_o.jpg]

Comet-Wine... Itza : makes you see ducks the redux
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
youareaduck
[Image: 20150813_Approaching_perihelion_Animation_f537.gif]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Incomming...Exactly how does one induct the fact that can't be ducked?!!!

Before hatmehit left expat banned as ma'at and all that ...Outbound


Quantum Random Walk.


He watched improv materialise what was the material eyes of the star spangled entangled banner.

He will NEVER forget he was once inside a maker-space.
In Fact he has a lone neuron created inside his noggin' that is like a sleeper cell of LMAO!!!  LilD
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
http://sci.esa.int/comet-viewer
[Image: 20611886503_d9e277f634_o.jpg]

http://sci.esa.int/comet-viewer
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
...

You have an image about a quarter way down on page 4 here that always crashes the thread on my computer..
In order to get past it, I have to slowly scrolll close to it,
then use the mouse to speed straight down past it,
and after a couple of attempts at timing I can get through to the rest of the thread.
I will try and find the image.
Thanks for keeping up with the news events on this comet. Applause

...

it is this post ... maybe the 4th image or so down ?

Thursday, July 16th, 2015, 04:23 am

...
Reply
This one???
http://www.esa.int/var/esa/storage/image...mage_2.jpg
[Image: Comet_boundaries_Anubis_and_Atum_to_Hapi...mage_2.jpg]
This image set highlights the boundaries between Anubis, Atum and Seth on the large lobe, and the transition between the neck and Anuket on the small lobe.



If it is... speaking of the crick in itz neck:



How the duck got its neck: youareaduck
Rapid temperature changes from self-(fore)shadowing may explain 67P's unusual activity and shape
[Image: lakdawalla-emily_headshot_9850_t233.jpg]
Can Ducks Quantum Random Slither?
Posted by Emily Lakdawalla
2015/09/11 16:04 UTC
Topics: Rosetta and Philae, comets, comet Churyumov-Gerasimenko, explaining science
When Rosetta approached comet Churyumov-Gerasimenko last summer, both its shape and its activity were surprising. It looked like two comets welded together at a skinny neck. But just as surprising, to comet researchers, was the fact that the cometary activity appeared to originate within the neck.

[Image: 20140904_ESA_ROSETTA_NAVCAM_20140902A_16...stitch.png]
ESA / Rosetta / NavCam / Emily Lakdawalla

Comet jets! NavCam view of comet Churyumov-Gerasimenko on September 2, 2014
A four-image mosaic of comet Churyumov-Gerasimenko taken by Rosetta on September 2, 2014 clearly shows at least two jets emanating from the "neck" region of the comet. 

Here's the reason that's such a surprise. The animation below was produced for Philae landing site selection, and it shows how much of the comet's surface was in sunlight at the time. Red areas are continuously illuminated, so are hottest. Cometary activity has to do with volatile materials (especially ices like water and carbon monoxide) being heated and sublimating. And yet the hottest regions on the comet -- its twin poles, one broad area on each lobe -- aren't making jets like the neck areas are. What gives?

[Image: spinny-model-from-landing-site-announcement.gif]
ESA / Rosetta / DLR / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA
Primary and backup landing sites for Philae (spinning shape model)
This 3D model of comet Churyumov-Gerasimenko was derived from OSIRIS image data. It is color-coded according to how much sunlight reaches the surface, where red is continuously illuminated, yellow is intermediate, and blue is often shaded. Site J, on the "head" of the comet, is the primary selected landing site, and Site C is a backup.

A new paper published in the Astrophysical Journal by Victor Alí-Lagoa, Marco Delbo', and Guy Libourel presents a possible explanation. The three scientists do work in thermophysical modeling -- they use physics to examine how changes in temperature propagate through solar system materials, and investigate what happens to those materials as their temperature changes.
They asked whether the comet's unusual shape might have any effects on the temperatures experienced from place to place on its surface. They took a model of the rotating comet and looked at how its surface temperatures change as parts of its surface cast shadows on other parts, or reflect sunlight into shadowed regions, for four different dates. In their model, they found that while the neck area of the comet doesn't experience the most extreme temperatures, it does experience the most extreme temperature changes, where baking-hot sunlit surfaces are suddenly sunk into very deep shadows, and just as suddenly lit up again. On the two lobes of the comet, temperature change happens at only a few kelvins per minute; in the neck region, it can spike or plunge by more than 30 kelvins per minute. Here's one of their model results -- look at how that neck lights up! The places on the comet where temperature changes the fastest correlate well with the positions of observed jets.

[Image: 20150911_arxiv_org_pdf_1509_03179v1.png]
Locations of rapid temperature changes on comet Churyumov-Gerasimenko

Figure from "Rapid temperature changes and the early activity on comet 67P/Churyumov-Gerasimenko," by Victor Alí-Lagoa, Marco Delbo', and Guy Libourel. "Epoch 2" refers to September 22, 2014. 


Why does the rate of temperature change matter? In previous work, Delbo' and Libourel and other workers have explored how thermal changes can cause cracking. More rapid temperature changes make for higher stresses and more rapid cracking. Cracks in a comet can expose volatile material that was previously protected from the vacuum of space. The exposure of the material might not happen instantly, but a pervasively cracked surface will erode more rapidly, so cracks accumulated when the comet is close to perihelion could break open later. The authors explain: "In this case, ice would progressively be exposed on the concave parts and would subsequently be available for sublimation when the temperatures increase sufficiently as the comet approaches perihelion once again."
If true, this thermal-shock-cracking scenario might also explain the comet's two-lobed shape. A small initial concavity on the surface -- maybe an impact crater -- could, over time, through positive feedback, grow into a comet-bisecting neck. The authors go on to speculate that "faster thermal cracking in concavities might also explain why water ice was detected on asteroids (24) Themis and (67) Cybele (Campins et al. 2010; Licandro et al. 2011) at heliocentric distances at which water ice is not expected to be stable," and that the process might be quite common on small bodies in the solar system.
I'll carry the speculation a little bit farther: if a positive feedback mechanism has made a two-lobed world out of a single-lobed one, surely it will continue until it breaks the comet right in half. If the mechanism is common in ice-rich small bodies, as the authors suggest, I wonder if this is a pretty rapid way to disintegrate them: strike your comet or ice-rich asteroid with a biggish object to create a concavity, then watch the concavity grow until it cuts the thing in two, each of the resulting pieces being much smaller than the original. It's a wonder we have any little icy worlds left to visit!

http://www.planetary.org/blogs/emily-lak...-neck.html
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply


Eh? Lefty?
[Image: 21462691701_fa3059c2bb_o.gif]
How Write I Am...  LilD
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
A Redneck Canuck??? I mean ...Canard???

[Image: 4sierks.jpg]

Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko
http://arxiv.org/abs/1509.02794

Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations
http://arxiv.org/abs/1509.02707

http://arxiv.org/abs/1509.03179
Rapid temperature changes and the early activity on comet 67P/Churyumov-Gerasimenko

[Image: new_1421951362.jpg]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Rosetta Mission: Ptolemy sniffs next piece of the comet puzzle
Date:
September 15, 2015


New results from Ptolemy – the OU led instrument on the Rosetta mission’s Philae lander, suggest that Comet 67P/Churyumov-Gerasimenko may be giving of different gases from different parts of its surface, making it heterogeneous in nature, Ptolemy – the gas analysis instrument on board Philae, has taken measurements of the concentration of volatile molecules at the lander’s final resting site, known as. Its findings have shown the presence of both water (H2O) and carbon dioxide (CO2), but of very little carbon monoxide (CO). These findings follow the first set of results published by the Ptolemy team last month which reported the presence of organic compounds in the surface dust on Comet 67P.

The Ptolemy team have been surprised by the results as, based on the findings of the ROSINA instrument on board the Rosetta orbiter, they were expecting to see larger concentrations of CO on the surface. ROSINA, like PTOLEMY, is a mass spectrometer and at the time of landing was analysing the gases rising from the surface some 30 km above Comet 67P. Results by ROSINA, acquired shortly before landing (published in January 2015), found that the concentration of CO, although variable, was up to four times that of CO2, whereas the Ptolemy measurements found that CO was about ten times less than CO2.

According to Dr Andrew Morse, lead author on the paper, these findings could suggest that either the coma gas composition changes through various chemical reactions as it moves away from the comet, or that the gas vaporised from the comet varies by location, making it a heterogeneous comet. He says: “Though it is a possibility that carbon monoxide is produced in the coma as it moves away from the comet, a more probable account of such a large change would be that the gases released from the comet’s surface differs according to location.”

One hypothesis is that a heterogeneous comet is the result of it being accumulated from diverse building blocks during its formation in the solar system. Alternatively it is the result of uneven heating in its journey into the inner solar system. The ROSINA instrument could help to answer this by making further measurements of the water coming off the comet’s surface. Dr Morse adds: “Our results, from Comet 67P’s surface, has both surprised us as well as opened up a variety of new questions about how comets form and how they work. We’re eagerly awaiting new results which should help us to clarify whether Comet 67P is indeed heterogeneous in nature or if there is another explanation. Either way, these results offer up an important piece of the complex, yet fascinating puzzle of how comets are formed.”

Co-author Dr Geraint Morgan says: “The questions raised by Ptolemy show the value of landers, even high risk ones, in establishing a ‘ground truth’ measurement on the surface to compare with on-going measurements from orbiting spacecraft.  Despite Philae’s eventful journey the data produced could be the key to help the Rosetta mission unlock the secrets of Solar System.”

The paper ‘Low CO/CO2 ratios of comet 67P measured at the Abydos landing site by the Ptolemy mass spectrometer’ was published in the academic journal Astronomy & Astrophysics. It was authored by the OU Ptolemy team which consists of Dr’s Andrew Morse, Simon Sheridan, Geraint Morgan, Dan Andrews, Simeon Barber and Professor Ian Wright, and Olivier Mousis from Laboratoire d'Astrophysique de Marseille.

Story Source:

The above post is reprinted from materials provided by Open University. Note: Materials may be edited for content and length.

Journal Reference:

A. Morse, O. Mousis, S. Sheridan, G. Morgan, D. Andrews, S. Barber, I. Wright. Low CO/CO_2 ratios of comet 67P measured at the Abydos landing site by the Ptolemy mass spectrometer. Astronomy & Astrophysics, 2015; DOI: 10.1051/0004-6361/201526624


[Image: 21315118619_e0246014b5_o.jpg]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Comet surface changes before Rosetta's eyes

[Image: 20941515520_90b3782c75_o.jpg]

Comet surface changes before Rosetta's eyes
September 22, 2015

[Image: 2-cometsurface.jpg]
Sequence of ten images showing changes in the Imhotep region on Comet 67P/Chruymov-Gerasimenko. The images were taken with the OSIRIS narrow-angle camera on Rosetta between 24 May and 11 July 2015. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

In the months leading to the perihelion of Comet 67P/Churyumov-Gerasimenko, Rosetta scientists have been witnessing dramatic and rapid surface changes on the Imhotep region, as reported in a paper to be published in Astronomy & Astrophysics

Since arriving at Comet 67P/C-G in August 2014, Rosetta has been witnessing an increase in the activity of the comet, warmed by the ever-closer Sun. A general increase in the outflow of gas and dust has been punctuated by the emergence of jets and dramatic rapid outbursts in the weeks around perihelion, the closest point to the Sun on the comet's orbit, which occurred on 13 August 2015.
But in June 2015, just two months before perihelion, Rosetta scientists started noticing important changes on the surface of the nucleus itself. These very significant alterations have been seen in Imhotep, a region containing smooth terrains covered by fine-grained material as well as large boulders, located on 67P/C-G's large lobe.
"We had been closely monitoring the Imhotep region since August 2014, and as late as May 2015, we had detected no changes down to scales of a tenth of a metre," comments Olivier Groussin, an astronomer at the Laboratoire d'Astrophysique de Marseille, France, OSIRIS Co-Investigator and lead author of the study.

"Then one morning we noticed that something new had happened: the surface of Imhotep had started to change dramatically. The changes kept going on for quite a while."
First evidence for a new, roughly round feature in Imhotep was seen in an image taken with Rosetta's OSIRIS narrow-angle camera on 3 June. Subsequent images later in June showed this feature growing in size, and being joined by a second round feature. By 2 July, they had reached diameters of roughly 220 m and 140 m, respectively, and another new feature began to appear.

[Image: 3-cometsurface.jpg]
Annotated version of the sequence of ten images showing changes in the Imhotep region on Comet 67P/Chruymov-Gerasimenko. The images were taken with the OSIRIS narrow-angle camera on Rosetta between 24 May and 11 July 2015. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

By the time of the last image used in this study, taken on 11 July, these three features had merged into one larger region and yet another two features had appeared.
"These spectacular changes are proceeding extremely rapidly, with the rims of the features expanding by a few tens of centimetres per hour. This highlights the complexity of the physical processes involved," adds Olivier.

[Image: 5-cometsurface.jpg]
The Imhotep region on Comet 67P/C-G on 3 June 2015. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The sublimation of volatile species is clearly an important factor, as colour images of this region reveal the signature of exposed ice on some of the rims of the newly-formed surface features. The rapid rate of expansion is unexpected, however: models of sunlight-driven sublimation would predict erosion rates of just a few centimetres per hour, and thus the scientists believe that additional mechanisms are required to explain the observations.

[Image: 4-cometsurface.jpg]
The Imhotep region on Comet 67P/C-G on 24 May 2015. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

A simple possibility is that the surface material is very weak, allowing for more rapid erosion, but it is also possible that the crystallisation of amorphous ice or the destabilisation of so-called 'clathrates' (a lattice of one kind of molecule containing other molecules) could liberate energy and thus drive the expansion of the features at faster speeds.
The erosion could be accompanied by increased rates of gas outflow, including H2O, CO2, or CO. The scientists also searched in OSIRIS images for evidence of increased dust rising from Imhotep as the surface morphology evolved, but did not find any.

[Image: 2-cometsurface.png]
Colour images of the Imhotep region on Comet 67P/C-G, taken with the OSIRIS narrow-angle camera on Rosetta on 18 June (upper row), 2 July (middle row) and 11 July 2015 (lower row). The first column shows images taken in the orange filter (649 nanometres); the second column shows the ratio between images taken with the blue filter (481 nanometres) and the orange filter for the 18 June and 2 July images, and the ratio between images taken with the blue and the red (701 nanometres) filters for the 11 July image; the third column shows a composite obtained by combining the images in the previous two columns. The yellow arrows indicate some of the new features that were detected on Imhotep. These colour images show that some patches on the surface of the comet reflect orange/red light less effectively and blue light more effectively than their surroundings. They appear as white in the central column, where the colour ratio is shown. This indicates the presence of frozen water ice at or just below the surface of these patches. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

While it is unlikely that many small (micron-sized) dust particles were released as the features formed and expanded, it is possible that the same amount of mass was released in a smaller number of larger (millimetre-sized) particles, which would produce less reflected light and thus be harder to detect with OSIRIS.
In addition, a significant fraction of the dust released may have immediately fallen back to the surface, accumulating at the base of the expanding rims.

[Image: 3-cometsurface.png]
Activity seen above the Imhotep region with the OSIRIS narrow-angle camera on Rosetta on 23 May 2015 (left), before significant morphological changes were seen in this region, and on 23 June 2015 (right), after the changes had begun to appear. (Times are in UT.) The positions of the first two new features that were seen in Imhotep are marked with A and B. The white arrows indicate the direction along which an increase of activity would have been seen in the case of jets lifting from the newly arisen features. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Although the scientists were initially surprised to see such significant changes taking place on smooth terrains such as those seen in Imhotep, the location of this region close to the comet's equator guarantees that it receives large amounts of sunlight.
"We are looking forward to combining our OSIRIS observations with data from other instruments on Rosetta, to piece together the origin of these curious features," concludes Olivier.

[Image: 6-cometsurface.jpg]
The Imhotep region on Comet 67P/C-G on 5 June 2015. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
 
Explore further: Rosetta gets a peek at Comet 67P's "underside"
More information: "Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko," A&A, Received: 21 July 2015 / Accepted: 08 September 2015 DOI: dx.doi.org/10.1051/0004-6361/201527020 
Journal reference: Astronomy & Astrophysics  
Provided by: European Space Agency

Read more at: http://phys.org/news/2015-09-comet-surfa...s.html#jCp

[Image: index.php?act=attach&type=post&id=37911]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Images obtained by OSIRIS, Rosetta’s scientific imaging system, show dwarf planet Pluto shortly before the flyby of NASA's New Horizons. 

[Image: 21451462529_212aaa9fb6_o.jpg]

http://rosetta.jpl.nasa.gov/news/hello-pluto

The image below will remind my mind...

That between the Osiris image and the pluto fly-bye 67p was speeding @ ~33.33 km/s @ ~194,712,206 km towards Sol.

[Image: 21647465461_72e28bd8c9_o.jpg]

Walking backwards looking forward is the foreword.

[Image: 17151570652_5b283026f7_o.jpg]

[Image: tminus12days.gif]
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
...
It is fascinating to watch the rapid changes of the comet surface features in the Imhotep area,
featured in that animation.
 
I then imagined a much larger long period comet perhaps like NEATV1,
and the surface changes over a wider area that would occur on that surface.
A sped up motion video of 1.5 months of that kind of surface action might be wild.



Quote: the destabilisation of so-called 'clathrates' could liberate energy
and thus drive the expansion of the features at faster speeds.

I wonder why they don't mention heat being released from such destabilization as well as energy,
or is that just to be assumed?
...
Reply
(09-23-2015, 03:20 AM)Vianova Wrote: I wonder why they don't mention heat being released from such destabilization as well as energy,
or is that just to be assumed?
...

This may answer your question. Arrow

ESA's Rosetta data reveals evidence for a daily water-ice cycle on and near the surface of comets
September 24, 2015

[Image: esasrosettad.jpg]
The water-ice cycle of Rosetta's comet. Credit: Data: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al. (2015); Comet: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0

Comets are celestial bodies comprising a mixture of dust and ices, which they periodically shed as they swing towards their closest point to the Sun along their highly eccentric orbits.

As sunlight heats the frozen nucleus of a comet, the ice in it – mainly water but also other 'volatiles' such as carbon monoxide and carbon dioxide – turns directly into a gas.
This gas flows away from the comet, carrying dust particles along. Together, gas and dust build up the bright halo and tails that are characteristic of comets.
Rosetta arrived at Comet 67P/Churyumov–Gerasimenko in August 2014 and has been studying it up close for over a year. On 13 August 2015, the comet reached the closest point to the Sun along its 6.5-year orbit, and is now moving back towards the outer Solar System.
A key feature that Rosetta's scientists are investigating is the way in which activity on the comet and the associated outgassing are driven, by monitoring the increasing activity on and around the comet since Rosetta's arrival.

Scientists using Rosetta's Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, have identified a region on the comet's surface where water ice appears and disappears in sync with its rotation period. Their findings are published today in the journal Nature.
"We found a mechanism that replenishes the surface of the comet with fresh ice at every rotation: this keeps the comet 'alive'," says Maria Cristina De Sanctis from INAF-IAPS in Rome, Italy, lead author of the study.
The team studied a set of data taken in September 2014, concentrating on a one square km region on the comet's neck. At the time, the comet was about 500 million km from the Sun and the neck was one of the most active areas.

[Image: 1-esasrosettad.jpg]
Hapi region on comet 67P/C-G. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al. (2015)

As the comet rotates, taking just over 12 hours to complete a full revolution, the various regions undergo different illumination.
"We saw the tell-tale signature of water ice in the spectra of the study region but only when certain portions were cast in shadow," says Maria Cristina.
"Conversely, when the Sun was shining on these regions, the ice was gone. This indicates a cyclical behaviour of water ice during each comet rotation."
The data suggest that water ice on and a few centimetres below the surface 'sublimates' when illuminated by sunlight, turning it into gas that then flows away from the comet. Then, as the comet rotates and the same region falls into darkness, the surface rapidly cools again.

However, the underlying layers remain warm owing to the sunlight they received in the previous hours, and, as a result, subsurface water ice keeps sublimating and finding its way to the surface through the comet's porous interior.
But as soon as this 'underground' water vapour reaches the cold surface, it freezes again, blanketing that patch of comet surface with a thin layer of fresh ice.
Eventually, as the Sun rises again over this part of the surface on the next comet day, the molecules in the newly formed ice layer are the first to sublimate and flow away from the comet, restarting the cycle.

[Image: 2-esasrosettad.jpg]
Water ice and surface temperature at Hapi. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al. (2015)

"We suspected such a water ice cycle might be at play at comets, on the basis of theoretical models and previous observations of other comets but now, thanks to Rosetta's extensive monitoring at 67P/Churyumov–Gerasimenko, we finally have observational proof," says Fabrizio Capaccioni, VIRTIS principal investigator at INAF-IAPS in Rome, Italy.
From these data, it is possible to estimate the relative abundance of water ice with respect to other material. Down to a few cm deep over the region of the portion of the comet nucleus that was surveyed, water ice accounts for 10–15% of the material and appears to be well-mixed with the other constituents.
The scientists also calculated how much water vapour was being emitted by the patch that they analysed with VIRTIS, and showed that this accounted for about 3% of the total amount of water vapour coming out from the whole comet at the same time, as measured by Rosetta's MIRO microwave sensor.
"It is possible that many patches across the surface were undergoing the same diurnal cycle, thus providing additional contributions to the overall outgassing of the comet," adds Dr Capaccioni.
The scientists are now busy analysing VIRTIS data collected in the following months, as the comet's activity increased around the closest approach to the Sun.
"These initial results give us a glimpse of what is happening underneath the surface, in the comet's interior," concludes Matt Taylor, ESA Rosetta Project Scientist.
"Rosetta is capable of tracking changes on the comet over short as well as longer time scales, and we are looking forward to combining all of this information to understand the evolution of this and other comets."
 Explore further: Rosetta measures comet's temperature
More information: "The diurnal cycle of water ice on comet 67P/Churyumov–Gerasimenko." Nature 525, 500–503 (24 September 2015) DOI: 10.1038/nature14869 
Journal reference: Nature  
Provided by: European Space Agency


Read more at: http://phys.org/news/2015-09-esa-rosetta...y.html#jCp

[Image: nature14869-f1.jpg]


Philae?

Jump Up^
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply



Philae??? Hmm2
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
ROSINA detects argon at Comet 67P/C-G



Quote:The noble gas argon has been detected in the coma of Comet 67P/Churyumov-Gerasimenko for the first time, thanks to the ROSINA mass spectrometer on-board Rosetta. Its detection is helping scientists to understand the processes at work during the comet’s formation, and adds to the debate about the role of comets in delivering various ‘ingredients’ to Earth.


The new results are reported in Science Advances today and describe data collected on 19, 20, 22, and 23 October 2014, when the comet was around 465 million km (3.1 AU) from the Sun, and Rosetta was in a 10 km orbit around the comet.
[Image: ESA_Rosetta_NAVCAM_141020_montagejpg-350x350.jpg]
Four image NAVCAM montage of Comet 67P/C-G comprising images taken on 20 October 2014, during the timeframe of the ROSINA measurements reported today. The images were taken about 7.4 km from the comet surface. Credits: ESA/Rosetta/NAVCAM

During the time spent close to the comet, the ROSINA instrument was able to take an inventory of the key constituents of the comet’s coma, with many ingredients already reported (see links at end of article). Determining the chemical make-up of comets is a necessary step to understanding their role in bringing water and other ingredients to the inner planets during the Solar System’s early history.
The so-called noble gases (helium, neon, argon, krypton, xenon, and radon) rarely react chemically with other elements to form molecules, mostly remaining in a stable atomic state, representative of the environment around a young star in which planets, comets, and asteroids are born.
In addition, their abundance and isotopic compositions can be compared to the values known for Earth and Mars, and for the solar wind and meteorites, for example. The relative abundance of noble gases in the atmospheres of terrestrial planets is largely controlled by the early evolution of the planets, including outgassing via geological processes, atmospheric loss, and/or delivery by asteroid or cometary bombardment. Thus the study of noble gases in comets can also provide information on these processes.
However, noble gases are very easily lost from comets through sublimation, and so this first detection of argon at Comet 67P/C-G is a key discovery. Not only that, but it is also an important step in determining if comets of this type played any significant role in the noble gas inventory of the terrestrial planets.
[Image: Argon-spectra-350x302.png]
ROSINA-DFMS mass spectra identifying the two isotopes of 36Ar and 38Ar in October 2014, along with other gases. The extreme high mass-resolution of DFMS is a prerequisite for separating and identifying the two argon isotopes. The spacecraft background spectrum was obtained on 2 August 2014, before the comet signal became apparent. (m/z) = mass/charge. Data from Balsiger et al (2015).

Scientists analysing data from ROSINA’s high-resolution Double Focusing Mass Spectrometer (DFMS) identified argon, along with other gases, in the coma spectra of Comet 67P/C-G in October 2014. They identified 36Ar and 38Ar, yielding an isotopic ratio for 36Ar/38Ar of 5.4 ± 1.4, which is compatible with Solar System values: for Earth, this isotopic ratio is 5.3, while for the solar wind it is 5.5.
The relative abundance of argon to other gases was also investigated. For example, the abundance of argon relative to water vapour was determined to be between 0.1 x 10^–5 and 2.3 x 10^–5, the range of values measured being due to variable solar illumination, which influences the rate of water sublimation on different parts of the comet nucleus.
“Even though the argon signal is very low overall, this unambiguous first in-situ detection of a noble gas at the comet demonstrates the impressive sensitivity of our instrument,” says Professor Kathrin Altwegg, principal investigator of the ROSINA instrument at the University of Bern.
“The argon-to-water ratio varied by more than a factor of 20. While the very volatile argon can escape under any conditions, water sublimation depends strongly on the amount of sunlight being received, and so with it the argon-to-water ratio,” explains Professor Hans Balsiger, also from the University of Bern, and lead author of the paper reporting the discovery.
“In contrast, the relative abundance of argon to molecular nitrogen is quite stable – explained by the fact that argon and nitrogen have similar high volatilities.”
Although the measured abundance of argon-to-water spans a wide range, it still has implications for the question of whether comets brought water to Earth. That is because the argon-to-water ratio at Earth is only 6.5 x 10^–8, several orders of magnitude lower than observed for 67P/C-G.
“The relatively high argon content of Comet 67P/C-G compared with Earth again argues against a cometary origin for terrestrial water, in an independent way to the similar finding indicated by the earlier ROSINA result on the deuterium-to-hydrogen ratio for 67P/C-G,” comments Hans.
The argon detection can also be used to learn about the conditions in which the comet formed.
“The argon we detected comes from inside the icy nucleus of the comet; the nature of that ice – how, when, and where it formed – determines how it captured and subsequently released the gases we are measuring” says Kathrin.
[Image: ESA_Rosetta_NAVCAM_20150921_enhanced-350x350.jpg]
Single frame enhanced NAVCAM image of Comet 67P/C-G taken on 21 September 2015. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

The two simplest forms of ice are crystalline and amorphous. These form at different temperatures and pressures, capturing and releasing gases in different ways. Argon, nitrogen, carbon monoxide, along with the heavier noble gases krypton and xenon are particularly useful for distinguishing between the various possibilities, because they remain in the same condition as when they were first incorporated into the comet.
Models can be used to predict how readily highly-volatile gases were incorporated into the icy grains that grew at low temperature in the protosolar nebula. These models show that the high abundance of argon at Comet 67P/C-G and the good correlation with nitrogen are both consistent with the comet forming in the cold outer reaches of the Solar System.
Almost a year has passed since these argon data were collected. Now that the comet has passed perihelion, its closest point to the Sun along its orbit, the density of the coma has increased greatly, implying that searches for even rarer gases should be possible.
However, the increased activity of 67P/C-G means that Rosetta cannot fly close to the comet without running into navigation issues, and therefore it is currently operating at distances greater than 350 km from the comet’s nucleus: this week, it has embarked on a trajectory taking it 1500 km from the comet in order to study the wider coma and plasma environment.
The ROSINA team are therefore eagerly waiting for Rosetta to return to closer distances as activity dies down in the coming months, in order to continue their investigation of the noble gases – including searching for krypton and xenon – to add further insights into the part played by comets in the delivery of these ingredients to Earth.
The paper “Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko,” by H. Balsiger et al is published online in Science Advances.
Related ROSINA blog articles:
The perfume of 67P/C-G 
Rosetta fuels debate on origin of Earth's oceans
Rosetta makes first detection of molecular nitrogen at a comet
Comet's coma composition varies significantly over time
Rosina tastes the comet's gases 
About ROSINA
ROSINA is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument and comprises two mass spectrometers: the Double Focusing Mass Spectrometer (DFMS) and the Reflectron Time of Flight mass spectrometer (RTOF) – and the COmetary Pressure Sensor (COPS). The measurements reported here were conducted with DFMS. The ROSINA team is led by Kathrin Altwegg of the University of Bern, Switzerland.

http://blogs.esa.int/rosetta/2015/09/25/...et-67pc-g/


Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko
http://advances.sciencemag.org/content/1...00377.full

Abstract
Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope 36Ar and by the 36Ar/38Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth’s major volatiles.


Keywords
  • Space science

  • comets

  • noble gas

  • Rosetta

  • 67P/Churyumov-Gerasimenko
The role of comets in the formation of the solar system has been the subject of numerous models and speculations. In particular, contributions to the volatiles of the inner planets, to Earth’s water reservoir, and even to life have been advocated [for example, (1) and references therein]. In any case, comets are thought to be among the most primitive objects in the solar system, having kept at least partially the volatile constituents of the solar nebula. Of the two identified families, the Oort Cloud Comets (OCCs) and the Kuiper Belt (also known as Jupiter family) Comets, the latter is considered to have formed beyond the orbit of Neptune at even lower temperatures than the OCCs.
One of the prime goals of the Rosetta mission (2) to comet 67P/Churyumov-Gerasimenko (hereafter 67P/CG), a Jupiter family comet, is the in situ measurement of the volatile inventory of 67P/CG with high sensitivity and high mass resolution. This allows comparisons to remote sensing measurements and to the only previous in situ measurement of a comet, Halley, an OCC. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis [ROSINA (3)] includes two mass spectrometers for this purpose, RTOF (reflectron type time of flight) and DFMS (double focusing mass spectrometer).
The determination of noble gases plays a key role in that volatile inventory. The abundance patterns and the isotope composition of the heavy noble gases, especially Xe, in the atmospheres of Earth and Mars do not fit the solar wind or the chondritic meteorites [for example, (1) and references therein]. To begin its study of noble gases, ROSINA detected argon in the coma of 67P/CG.
DFMS is a mass spectrometer that measures the neutral composition of the coma at the position of the spacecraft with unprecedented mass resolution. The DFMS capability to measure argon at 67P/CG has been demonstrated using the DFMS laboratory model and adapted to the expected signal at the comet (4). However, the measured spectrum (Fig. 1) shows other mass peaks near m/z (mass/charge ratio) = 36 (m/z = 35.9670, electron subtracted) that must be considered. H35Cl (m/z = 35.9761) is present in the background because of spacecraft outgassing (5). The spacecraft background shown in Fig. 1 was measured on 2 August 2014, when Rosetta was at a heliocentric distance of 3.6 AU, almost 800 km from the nucleus and clearly before the cometary signal became apparent. In the mass spectrum near m/z 38, the only signal close enough to interfere with 38Ar (m/z = 37.9622) was assumed to be H37Cl (m/z = 37.9732). Its amount, evaluated from H35Cl assuming a solar isotopic ratio for chlorine, was found to be small due to higher mass separation at m/z = 38 (see overlap in Fig. 1). Not foreseen by Hässig et al. (4) was the interference by C32S2++ (m/z = 37.9715) on m/z 38. Together with H35Cl, it led to corrections in the procedure. The identification of C32S2++ was confirmed by identifying C32S2+ at m/z 76. The cross section for electron-impact ionization for C32S2++ is 3 to 6% of C32S2+ (6), which agrees with our finding.
[Image: F1.medium.gif] Fig. 1DFMS mass spectra in the m/z ranges of 36 and 38.
The spectra demonstrate the clear identification of the two isotopes 36Ar and38Ar and of the interfering molecules. The exact m/z locations are given in the text. The spacecraft background spectra were obtained before the cometary signal became apparent (2 August 2014, heliocentric distance of 3.6 AU, almost 800 km from the nucleus).



The argon data presented here were taken on 19, 20, 22, and 23 October 2014. Comet 67P/CG was at ~3.1 AU from the Sun, and the spacecraft was roughly 10 km away from the comet during this time period. To resolve the peaks at m/z 36 and the peaks at m/z 38 (Fig. 1), we used a fitting method corresponding to Hässig et al. (4). A possible interference from 36S (m/z= 35.9665) is <2% based on the signal for 32S. Because the signal for 38Ar was close to the instrument background, it was summed up over the full time period to reduce statistical uncertainties. The same method was applied to 36Ar. Uncertainties of the measurements were estimated by error propagation and were due to the ion counting statistics, offset variation, and nonsynchronous measurements of the two isotopes (25%). The resulting average ratio36Ar/38Ar was 5.4 ± 1.4 (Earth, 5.3; solar wind, 5.5). Hence, despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope 36Ar and by means of the 36Ar/38Ar isotopic ratio, which is compatible with solar system values.
To constrain a possible contribution of cometary argon to Earth’s atmosphere, the abundance of argon relative to water is important. 36Ar and H2O were measured during the abovementioned four periods in October 2014, with individual measurements covering 20 s (Fig. 2A). The spread of data, as given in Fig. 2A and Table 1, is due to temporal variability and spatial heterogeneity of the coma (7). Our values for 36Ar/H2O, (0.1 to 2.3) × 10−5 (molecular ratio), are compatible with (8), one to two orders of magnitude below their upper limits determined by remote sensing of three long-period comets.
[Image: F2.medium.gif] Fig. 2(A and B) Comparison of argon abundances to water (A) and to molecular nitrogen (B).
(A and B) Relative abundances of 36Ar versus H2O (A) and N2 (B). 36Ar abundances were measured relative to water and molecular nitrogen during four periods in October 2014, when Rosetta was close to 67P/CG (10 km). Individual measurements cover 20 s. Measured particles per 20 s are plotted. Ratios are molecular ratios. (A) Large spread of the relative abundances due to the high temporal variability and spatial heterogeneity of the coma (7). (B) Good correlation between 36Ar and N2 due to their similar volatility.



Table 1 Argon isotopic ratio and relative abundances to H2O and N2.
The isotopic ratio of the comet’s argon is in agreement with the solar system values.

View this table:
Correlations with other molecules were also investigated. The good correlation between 36Ar and N2 (Fig. 2B) due to their very similar volatility is noteworthy. The relative abundance is (9.1 ± 0.3) × 10−3 (molecular ratio). However, one has to be careful; carbon monoxide of similar volatility does not show such a strong correlation to molecular nitrogen and hence argon (9) as well. This indicates that other processes are involved, causing the observed temporal variability and spatial heterogeneity.
The argon we detected comes from inside the icy nucleus of the comet. The nature of that ice and how, when, and where it formed determined how it captured and released the gases we are measuring. The two simplest forms of ice are crystalline and amorphous. They form at different temperatures and pressures, capturing and releasing gases in different ways. Ar, N2, CO, Kr, and Xe are particularly useful for distinguishing among these various possibilities; they lead us back to the manner of the comet’s origin. They also constrain possible cometary contributions to the inner planets. Thus, the detection of Ar is a major step forward in our investigation of the comet. Several models predict the inclusion of highly volatile gases into the icy grains that grew at low temperature in the protosolar nebula. The high abundance of argon as well as the good correlation with N2 are both consistent with these ideas. For a discussion, we refer to Ruben et al. (9).
The high content of argon in comet 67P/CG, if typical of outer solar system bodies, has strong implications for the origin of volatile elements on Earth and the other terrestrial planets. The elevated deuterium/hydrogen (D/H) ratio of 67P/CG [three times the ocean value (10)] is not consistent with a comet like this supplying Earth’s oceans. However, the recent report of an ocean-like D/H value in the Jupiter family comet 103P/Hartley 2 (11) has revived the idea of a possible cometary contribution to Earth’s volatiles and suggested that, even within an established “family,” comets are isotopically heterogeneous. The present measurement offers an independent test for a possible link between a cometary reservoir and the terrestrial atmosphere and oceans, albeit in the same comet. The 36Ar/H2O ratio of Earth’s surface (hydrosphere plus atmosphere) is 6.5 × 10−8 (1213), that is, more than one to two orders of magnitude lower than the range of values [(0.1 to 2.3) × 10−5] measured in 67P/CG gases. Thus, adding 67P/CG-like water to a dry Earth would result in several orders of magnitude more argon in the atmosphere than is observed. Unfortunately, there is no measurement of argon from comet 103P/Hartley 2. It is possible that atmospheric gases could have been lost preferentially relative to the ocean water during giant impacts characterizing the end of the terrestrial accretion (1415) and/or irradiation of the early atmosphere from the young active sun (1617). However, the efficiency of such a process is unlikely to have resulted in the loss of >99% Ar while essentially preserving liquid water on Earth’s surface.
Combining the D/H and 36Ar/H2O ratios measured in the coma of 67P/CG provides a means of quantification of a possible cometary contribution to Earth from a body with volatile content, such as 67P/CG (Fig. 3). Earth is represented by the surface inventory (hydrosphere plus atmosphere) and by bulk Earth (surface plus deep Earth) estimates from (17) and (18), respectively. Clearly, an asteroidal component, represented by carbonaceous chondrites CI and CM in Fig. 3, makes a better potential contributor to terrestrial water [and other major volatiles such as C and N (17)] than comets. Mixing curves between the two components allows the definition of potential cometary contributions, assuming no fractionation of the 36Ar/H2O ratio during delivery. Depending on the 36Ar/H2O values adopted for bulk Earth, a contribution of cometary argon to the atmosphere is possible, but a contribution of 67P/CG-like material to terrestrial water is negligible in all cases. If one considers bulk Earth composition as defined by Marty (17) (lower limit of the 36Ar/H2O in Fig. 3), a bulk terrestrial 36Ar/H2O ratio close to chondritic leaves no room for significant contribution of 67P/CG-like material to the major volatiles on Earth.
[Image: F3.medium.gif] Fig. 3D/H versus 36Ar/H2O mixing of 67P/CG-like and asteroidal materials.
The asteroidal composition is represented by the Orgueil (CI) and Murchison (CM) carbonaceous chondrites. CI/CM chondrites are considered as the best representatives of volatile-rich primitive meteorites (19). Cometary data: this work, Altwegg et al. (10). Meteorite data: Mazor et al., Bogard et al., and Kerridge (2022). Earth data, surface inventory: Lécuyer et al. and Ozima et al.(1213). Range of estimates for bulk Earth: Marty and Halliday (1718).



Have comets left any traces of their undeniable impacts on the inner planets? Later in the mission, when the density in the coma has increased, ROSINA will seek to add the abundances of krypton and xenon in 67P/CG to the argon we now know is present, as one more test of this possibility. In conclusion, the high argon content of Comet 67P/CG argues against a cometary origin for terrestrial water, as does independently the elevated D/H ratio of this comet (10).
This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

http://advances.sciencemag.org/content/1...00377.full
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
Comet 67P/Churyumov–Gerasimenko

Incomming...YOU ARE  Sheep A DUCK!!!








Rosetta comet likely formed from two separate objects
September 28, 2015

[Image: rosettacomet.jpg]
The Aug. 22, 2014 photo taken by the Navcam of the Rosetta space probe and released by European Space Agency ESA on Monday, Sept. 28, 2015 shows Comet 67P/Churyumov–Gerasimenko. Researchers have now concluded that the comet was probably formed when two separate objects collided during the early stages of the Solar System, according to a paper published Monday in the journal Nature. (ESA/Rosetta/Navcam via AP)


Read more at: http://phys.org/news/2015-09-rosetta-comet.html#jCp

The characteristic "rubber duck" shape of the comet carrying a European robot probe through space 

[Image: 150716-charon_5385b1af7737d7c061e1fc7b1f...00-800.jpg]
was the result of a low-velocity impact billions of years ago between two objects which fused, a study said Monday.

Comet 67P/Churyumov-Gerasimenko's quirky double-lobed form left scientists scratching their heads ever since the ancient cosmic traveller first came into the Rosetta spacecraft's viewfinder last year.
Was it the result of a crash, or did the central "neck" linking the comet's "head" and "body" form through a process of erosion?
Now an international team says it has solved the riddle, affirming in the science journal Nature that: "comet 67P/Churyumov-Gerasimenko is (made) of two distinct objects".
"We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals (mini-comets) in the early stages of the Solar System", which formed some 4.6 billion years ago, the scientists said.

he proof, they explained, was found in differences between the onion-like layers of the two lobes.
Using sophisticated imaging systems on board Rosetta, the team discovered that the larger lobe was made up of layers up to 650 metres (2,100 feet) thick, "clearly independent" of the layers in the smaller portion.
But there were many similarities, which suggested the two mini-comets "formed completely independently" before bumping into one another, the scientists said.
"These two bodies should have collied very slowly and merged very slowly otherwise we would not have this ordered (onion-like) structure," team member Matteo Massironi said in a webcast press briefing on Monday.
[Image: 560958f798088.jpg]
ROSETTA-OSIRIS view of 67P/Churyumov-Gerasimenko comet. In the foreground is the head with roundish pits of layered material and smooth surfaces of incoherent deposits, in the background the irregular, fractured and stratified morphology of the body, in-between the smooth Hapi region. The image has been acquired by the OSIRIS Narrow angle camera on 2014-09-20 at a distance of 27.6 km from the comet. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA


He added the "two pieces were probably not formed in the same place, but formed in the same way."
The European Space Agency's Rosetta craft arrived at the comet, and entered its orbit, on August 6 last year after a decade-long, 6.5-billion-kilometre (four-billion-mile) journey through space.
After its launch in March 2004, the craft was catapulted around the Solar System with gravity boosts from Mars and Earth on four flybys between 2005 and 2009, before being placed in hibernation in June 2011 to conserve energy.
It awoke in January last year, and started its comet approach.
Bumpy landing
Six months later came the shock: as the icy dust ball came into focus, it became clear that 67P had a highly irregular rubber-duck silhouette, not the uniform potato shape scientists had expected.

This limited the choice of landing site for Rosetta's precious payload: a 100-kilogramme (220-pound), washing machine-sized robot lab dubbed Philae, designed to sniff and prod the comet on site.
[Image: 56095908a270f.jpg]
3D shape model and gravity field vectors of the 67P/Churyumov-Gerasimenko comet. The green line represents the local gravity vectors. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Finally, on November 12 last year, Philae touched down after a nail-biting seven-hour, 20-kilometre descent from Rosetta, but the landing was bumpy and the little probe ended up in a shaded ditch.
It had enough onboard power for three days of experiments before going to sleep on November 15.
But as 67P drew closer to the Sun, Philae recharged and woke up on June 13, only to fall silent again less than a month later after eight intermittent communications with Earth.
Rosetta, in the meantime, has continued its comet-probing duties with a palette of 11 science instruments—cameras, radar, microwave, infrared and other sensors to analyse the comet surface and gases escaping from it.
The mission was conceived to unravel the mysteries of comets, which many scientists believe "seeded" early Earth with some of the ingredients for life.
"This work proves for the first time that gentle collisions and merging do occur and lead to bilobate (dual-lobe) shape bodies in the Early Solar System," Massironi told AFP by email.
"Our results may provide an important clue on how the planets and the comets formed, and in the latter case where."
[Image: 1x1.gif] Explore further: Rosetta's view of a comet's "great divide"
More information: The two independent and primitive envelopes of the bilobate nucleus of comet 67P, DOI: 10.1038/nature15511 
Journal reference: Nature 

All Ma'at @ that:   dual youareaduck duel
[Image: 21181760803_dd8054d050_o.jpg]
Can't hardly wait to see this canard's fate... quack.

Stay Tuned.

67p See the Scenario in  Sintered Stereo.

http://phys.org/news/2015-09-rosetta-comet.html#nRlv
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
and sometimes Twin cells do not completely divide into two separate entities .
Nodules do not always completely split.
Never invite a Yoda to a frog leg dinner.
Go ahead invite Yoda to a Frog leg dinner
Reply
(09-29-2015, 12:42 PM)Wook Wrote: and sometimes Twin cells do not completely divide into two separate entities .
Nodules do not always completely split.

67P reveals recipe for a comet
Take two smaller comets and add a cosmic smashup
By
Christopher Crockett
10:42am, September 28, 2015 


[Image: 092515_cc_rosetta_free.jpg]
TWO FOR ONE  The two lobes of comet 67P, seen in this August 2014 image from the Rosetta spacecraft, probably came from two different comets, a new study suggests.

MPS for OSIRIS Team/Rosetta/ESA, MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
To make one oddly shaped comet, take two smaller comets and squish them together. That probably explains why comet 67P/Churyumov-Gerasimenko looks like a rubber duck, a new study reports.
Since the Rosetta spacecraft’s arrival last August (SN: 9/6/14, p. 8), researchers have debated whether 67P was a comet that lost some weight around its waistline or two comets that got a little too attached to one another. Layers and terraces on cliffs gave away 67P’s coupling. Mismatched layers between the head and body imply that the two lobes formed independently and later fused together, Matteo Massironi, a geologist at the University of Padua in Italy, and colleagues report online September 28 in Nature.

Assimilated Quack.
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)