This, to my knowledge, is the first refereed paper to be published on Rosetta's observations of C-G (and it's free to access!):
The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta

just out and already making noise on the social networks:
67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

So here's a question. Apparently 67P was originally from the Kuiper Belt, but has been a Jupiter family comet for at least the last few centuries. A bit of googling doesn't turn up a strong estimate for when that transition occurred, though.

We know that water loss by evaporation, sublimation or UV cracking can affect DE/H ratios. Could a few million years of warm/cool cycles have done this for 67P?


Doug M.

Yes - there is a substantial difference in vapour pressure between light and heavy water ices (Vapor pressure of ice containing D₂O by Matsuo et al., 1964: 10.1126/science.145.3639.1454), which could lead to fractionation via a process such as sublimation. Indeed the fractionation factor for D₂O into the ice phase increases at lower T. Since 67P gives every appearance of having a highly porous but very strong substrate, I suspect that it is a well-sintered matrix of large grains cemented together by growth from a vapour phase transported through the large (and possibly well connected network of) interstitial pores.
As such, the D/H ratio may be a reflection of the degree of sintering and the thermal regime under which it occurred.

Thank you -- that's very interesting.

If the ratio is a function of fractionation thanks to different vapor pressures, then you'd expect it to be highest where there's been most activity already, i.e. at the surface. It does make me wonder if we might see a shift in D/H as the comet gets closer to the Sun and more active. (The assumption here is that greater activity leads to outgassing from deeper inside the comet, which of course may not be the case.)


Doug M.

live stream of the AGU fall meeting press conference: http://www.ustream.tv/nasajpl2

I'm sure there will also be a recording available once the live stream is over.

https://virtualoptions.agu.org/category/Fal...cience/25431692

ADMIN: Requires a registration to view filed recordings.

this just out: 67P/Churyumov-Gerasimenko: Activity between March and June 2014 as observed from Rosetta/OSIRIS

Here you can view official hires ROLIS descent images:
https://virtualoptions.agu.org/media/P34B-0...tola/0_m432jt2i

I don't know if now they're also available for download somewhere .


ADMIN: Once again, requires a registration to view filed recordings. You obviously never bothered to look at the comments on your previous posts in this thread.

The recording of the press conference can be seen on ustream.

The link mcgyver posted leads to the archive of the recorded talks at the AGU Fall Meeting last week. Yes, a registration is needed, but it's free and I have never seen free recordings from a scientific conference. As Emily Lakdawalla tweeted, the search word Rosetta gives all Rosetta/Philae related talks in the archive. Until now, 20 are listed: https://virtualoptions.agu.org/search/rosetta

The registration is worth it, for example in the talk from Stefano Mottola about the ROLIS results, all seven ROLIS images of the descent of Philae are shown and the ones from the last landing site with all the colour filters. I haven't seen all talks, some are quite, say "scientific", but what have I expected?
I think it's quite an opportunity to see the talks without attending the conference and without paying the conference fee.

Edit: I see, links to some of the talks and the ROLIS images have been posted in the other thread. (But hearing all the information from the scientists is better than seeing just the pictures.)

Of course: it's the same site linked above. Same conditions apply. Thanks for stressing it.

I have just tried to register and a charge of, I think, $50 was requested. I'm accessing from the Canary Islands, so perhaps that influences this?
I didn't continue with registration, not because the fee is excessive but because I'm only able to access the internet via an Android tablet at present, and anything that needs Flash is not viewable. (So I was simply checking to see if the files did need Flash, as ustream does but Livestream and YouTube don't)

By the way, the AGU Rosetta press conference is available on YouTube on the AGU channel. I won't try to post the link, as I assume that I will not yet have posting permission for hyperlinks.

Margarita

PS - later edit! I went back to the site and discovered I'd not read it properly. (Duh) The $50 is charged and then discounted !! So, no fee. I registered and have discovered that the videos are viewable on the Android tablet

here you go! today's Science has a first batch of Rosetta @ CG papers!
http://www.sciencemag.org/content/347/6220.toc

these two papers and their supplementary materials in particular have lots of OSIRIS imagery:
The morphological diversity of comet 67P/Churyumov-Gerasimenko
On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko

and some OSIRIS images finally online at ESA
http://www.esa.int/Our_Activities/Space_Sc...Comet_close-ups

Great stuff, wonderful results - and maps showing the naming convention being developed. I imagine those name illustrations will show up on the Rosetta site.

Phil

One of the supplements (Morphological Diversity) gives the following:

Fantastic papers and image release...

Remember in 1965 waiting for the Sky & Telescope edition that would report on Mariner 4 images from Mars.
Now 50 years later I can sit on my couch using my 10.1 inch tablet to wander the Lovecraftian landscapes of a worldlet.

How cool is that...

Craig

It occurs to me that, if the RSI were focused on a point on the surface, and has sufficiently fine time resolution, it might be feasible to perform remote seismology studies (similar to helioseismology). Passive observation of reflected solar radiation might be sufficient, or it might require active transmission and simultaneous monitoring of the response. It would be really neat to hear the internal sounds of an active comet. Presumably Philae would have provided more direct measurements of this.

the Science cover is just... wow!!!!!!

I don't know if people noticed, but for MIRO the Acknowledgement in one Science article notes at which exact date data for the instrument will be deposited in PSA and PDS - 19 May 2015.

more goodies, from Nature this time: Comet 67P/Churyumov-Gerasimenko sheds dust coat accumulated over the past four years

I think nobody is talking about this here, but I think it's an amazing scientific result: Rosetta detected 350 micro-asteroids orbiting around 67P!!


http://blogs.esa.int/rosetta/2015/01/22/gi...nts-3-7-3-4-au/

Supplemental material gives more details: microsatellites were detected not by the dust grain detector (GIADA) but by the OSIRIS camera:

(so we have at least 25 hires images awaiting for release )

Whoa. I only did a quick initial scan the Rotundi, et al paper, but those grains are HUGE. I was thinking mm- to cm-sized particles. They are likely silicate/organics (doubtful with any ice) "fluffballs".

-Bill

At AGU Sierks showed one of the photos with this "snow" of particles in bound orbits. A few looked exactly as described in the paper -- alternating bright and dark, which he said you could use to determine their spin rate. So far we've pretty much only seen releases of OSIRIS images of the nucleus, none of these aimed at particles near the nucleus. I can't wait for the data set release to examine those.

Related to the OSIRIS team morphology results. Here are some selections from the recent Lander Search image. I have tried to find examples of the types of terrain highlighted in the reports. To keep this post short my comments, guesses and theories(?) are given in the image descriptions.

https://www.flickr.com/photos/124013840@N06...in/photostream/

https://www.flickr.com/photos/124013840@N06...in/photostream/

https://www.flickr.com/photos/124013840@N06...in/photostream/

https://www.flickr.com/photos/124013840@N06...in/photostream/

I'm no geologist, so any suggestions/admonishments by those more qualified would be appreciated. Certainly Bill H. knows a whole lot more than me about this subject and no doubt Emily is writing a blog about this OSIRIS image for the Planetary Society right now.

http://blogs.esa.int/rosetta/2015/02/09/se...sts-for-67pc-g/

Scientists from Rosetta’s OSIRIS team have been analysing the images of Comet 67P/Churyumov-Gerasimenko and comparing them to a thermal model to estimate how much material the various parts of the comet will lose through Sun-driven sublimation during one orbit. That is, as the Sun heats the comet, ices sublimate and the resulting gases drag dust into the comet’s coma
(…)

“Assuming that four times more dust is emitted than ice, our model leads to very different scenarios for the northern and southern hemisphere,” says OSIRIS scientist Stefano Mottola from the Institute for Planetary Research of the German Aerospace Center (DLR). “While during its short but intense summer the southern hemisphere may lose a surface layer measuring up to 20 metres in thickness, this value should be much smaller for the northern hemisphere. According to our estimations, only very few prominent peaks and cliffs may erode by more than ten metres over the course of one orbit.”

The Max Planck Institute for Solar System Research press release is at this URL
Rosetta: Comet’s South Heats Up

The fact that the south side sublimes away faster than the north because it is facing the sun at perihelion provides a possible reason for the asymmetric position of the neck, offset from the centre line between the two lobes. When the contact binary formed the neck would have been on the centre line but the missing material has left it off to one side, giving the duck a north facing 'chin'. This narrative implies that at perihelion mass loss will occur more from the lobes than the neck, contrasting with what we see now as the northern hemi-object is illuminated. Let's see if that happens.

Regarding mass loss in the neck region they've a backdoor:

If it's richer in CO2 or CO the neck region may lose mass, too.
Maybe they find out more detail about the compositional variations during the close flyby to come.

Yep, that statement fits. The southern face should experience most of the sublimation at perihelion, but the nothern face willl be most actve in the periods before and after.

Not sure where to put this...

Introducing the NAVCAM image browser
http://blogs.esa.int/rosetta/2015/03/06/in...-image-browser/


"We are happy to announce that the first set of images from Rosetta's NAVCAM has now been made available to all scientific and public users via ESA’s Planetary Science Archive (PSA). This first batch of image data covers the period leading up to 2 July 2014, prior to Rosetta’s arrival at 67P/C-G. Further releases of image data will be made in blocks on a monthly basis henceforth, with the near-term aim to catch-up so that NAVCAM data will be publicly released six months after they are taken."

Following Phil's link in another thread, looks like another batch of Rosetta papers coming soon, but of course even the abstracts are fascinating.

From agenda of European Geosciences Union General Assembly 2015

Rosetta: first results from the prime mission
Convener: Matthew Taylor | Co-Convener: Stephan ULAMEC
Orals / Mon, 13 Apr, 13:30–17:15 / Room Y5 / Tue, 14 Apr, 10:30–12:00 / 13:30–17:30 / Room Y5
Posters / Attendance Mon, 13 Apr, 17:30–19:00 / Red Posters

Lots there.

From the 46th Lunar and Planetary Science Conference

http://www.hou.usra.edu/meetings/lpsc2015/pdf/sess103.pdf

http://www.hou.usra.edu/meetings/lpsc2015/pdf/sess631.pdf

Is the neck region having a different composition really a sign of CG being a contact binary? Seems to me more like a single object with more ices near the center that are now exposed? This question was touched upon at a talk last evening by Joel Parker of the Southwest Research Institute (and the ALICE instrument).

A contact binary would probably be more interesting, but I share your preference for exposure of fresh interiour material of a single object.
Once the outermost crust is lost, sublimation may progress faster in that area, resulting in forming the neck.
The sublimation process of a prestine rotating cometary nucleus may start either near the equator for a spin axis parallel to the orbital axis, or near one of the poles if the pole happens to be directed towards the Sun near perihelion (skipping other options).
Taking the equator version the rotation axis may change (or precess) due to a change of the axis of maximum moment of inertia due to preferred mass loss of the nucleus near the equator.

This preferential sublimation process seems interesting to me in for example how it might be modeled. Good food for thought with Gerald's scenarios. It also seems plausible in explaining some other similarly shaped comets.

What still keeps me from accepting the excavated neck story are the large pits on the main body that are closest to the crack in the neck. These have the appearance of some of the other vent pits on both bodies. If they are indeed expired vents, then they had to have formed earlier than the scree/talus that now spills into them from the head. They do not match the valley wall morphology further up the neck; they are positioned facing outward relative to the main body, and circular as if not influenced by earlier neck material. I just can't conceive a history of their formation relative to neck material deflation that would have been happening at the same time, were this a unified object rather than a piece rotated into place at a later era. I see the refill history of those pits as telling something about the sequence of activity/erosion in the neck.

BTW, if you have access to Science the nitrogen discovery paper is here:
Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature

I was thinking about the 'Contact Binary. and the 'Eroded Neck' theories going on and thought I would add my twopence worth in favour of the 'Eroded Neck. camp.

While browsing here http://blogs.esa.int/rosetta/2015/03/20/co...-6-hours-later/

This image

Click to view attachment

and this comment

"On the large lobe, another striking feature catches the eye: the Aten region, an elongated depression between Ash, to the left, and Khepry, to the right."

The difference between the smoother,elongated. central region compared to the left and right regions on the larger lobe, to my eye, also applies to the smaller lobe.

This would indicate the same process happened to both lobes together.

In other words they are the same object.

I'm not sure I understand that reasoning. If we assume that the perihelion passages reforms the surface of the bodies, then the main surface features of both lobes would have been shaped by the same process at the same time regardless of whether it's a contact binary or not. If it is a binary object then they presumably joined before becoming a comet after all. It might indicate that both lobes have similar/same composition, but not that 67p is necessarily a single object.

Fair point!

The ratio between central area and left/right, also seems similar between the two lobes.....mmmmmmm...

So your rationale seems plausible for a contact binary. (As do others)

Lucky it's only twopence, but that's the beauty of armchair exploration.

Game on !!

Since we had a link to AGU webstreaming here's the European counterpart, albeit only with a single press conference streamed for Rosetta:

http://client.cntv.at/egu2015/PC1

Ulamec, Taylor and the PIs of ROMAP and RPC-MAG. Live on Tuesday, 1200 to 1300 UTC+2 (CEST).
Before that the stream will show previous press conferences (and something that looks like standup comedy in the press conference room in Austrian inbetween )

The above stream link offers a chat function to submit questions for the press conference remotely.

Related speech at EGU 2015: http://meetingorganizer.copernicus.org/EGU2015/session/17358

Abstracts for all speeches on Rosetta at EGU 2015 today and tomorrow: http://meetingorganizer.copernicus.org/EGU2015/orals/17358
And, perhaps oddly, abstracts for the poster session: http://meetingorganizer.copernicus.org/EGU2015/posters/17358
(edit: those two already posted earlier in this thread, here for completeness.)

Thank you for the heads up katodomo, the stream is over but a video is now available. It deals mostly with Philae and the magnetic field of the comet, magnetic field information is also in a new Rosetta blog post (http://blogs.esa.int/rosetta/2015/04/14/ro...not-magnetised/).

and the Science preprint: The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko

Freely available new papers with early OSIRIS results now online:
http://arxiv.org/abs/1505.06888 (Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft)
http://arxiv.org/abs/1505.07021 (Comet 67P/Churyumov-Gerasimenko: Constraints on its origin from OSIRIS observations)

the second paper is particularly interesting, as it shows that 67P appears to be a contact binary after all

Obviously these papers are not for the general public consumption, because I hardly understood any of it, and all those equations !

They are looking at the mechanics and seeing if Kepler, et al think that the contact binary could happen.

In a way, with an object that has formed through accretion, where is the line drawn on the size of the accretionary elements? Parts up to one-quarter to one-half Km in size are identifiable, in addition to the two major lobes. And different morphologies of different regions can be attributed to differences in erosional characteristics.

It's a whole different world.

--Bill

early results from the ALICE UV spectrometer (in free access): Measurements of the near-nucleus coma of comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta