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Rosetta scientific results
Paolo
post Sep 12 2014, 03:33 PM
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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
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Paolo
post Dec 10 2014, 08:39 PM
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just out and already making noise on the social networks:
67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

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The provenance of water and organic compounds on the Earth and other terrestrial planets has been discussed for a long time without reaching a consensus. One of the best means to distinguish between different scenarios is by determining the D/H ratios in the reservoirs for comets and the Earth’s oceans. Here we report the direct in situ measurement of the D/H ratio in the Jupiter family comet 67P/Churyumov-Gerasimenko by the ROSINA mass spectrometer aboard ESA’s Rosetta spacecraft, which is found to be (5.3 ± 0.7) × 10−4, that is, ~3 times the terrestrial value. Previous cometary measurements and our new finding suggest a wide range of D/H ratios in the water within Jupiter family objects and preclude the idea that this reservoir is solely composed of Earth ocean-like water.
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Doug M.
post Dec 11 2014, 04:47 AM
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QUOTE (Paolo @ Dec 10 2014, 09:39 PM) *
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.
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DFortes
post Dec 11 2014, 06:36 AM
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QUOTE (Doug M. @ Dec 11 2014, 04:47 AM) *
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.
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Doug M.
post Dec 14 2014, 08:37 PM
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QUOTE (DFortes @ Dec 11 2014, 07:36 AM) *
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.
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Weywot
post Dec 17 2014, 04:27 PM
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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.
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mcgyver
post Dec 19 2014, 10:57 AM
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QUOTE (Weywot @ Dec 17 2014, 05:27 PM) *
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.
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Paolo
post Dec 19 2014, 07:42 PM
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this just out: 67P/Churyumov-Gerasimenko: Activity between March and June 2014 as observed from Rosetta/OSIRIS
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mcgyver
post Dec 20 2014, 04:35 PM
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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.
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Weywot
post Dec 21 2014, 06:37 PM
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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? wink.gif
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.)
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mcgyver
post Dec 22 2014, 12:36 AM
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QUOTE (mcgyver @ Dec 20 2014, 05:35 PM) *

ADMIN: Once again, requires a registration

Of course: it's the same site linked above. Same conditions apply. Thanks for stressing it.
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MargaritaMc
post Dec 24 2014, 05:26 PM
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QUOTE (mcgyver @ Dec 22 2014, 12:36 AM) *
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


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Paolo
post Jan 22 2015, 06:57 PM
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here you go! today's Science has a first batch of Rosetta @ CG papers!
http://www.sciencemag.org/content/347/6220.toc
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Paolo
post Jan 22 2015, 07:09 PM
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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
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Paolo
post Jan 22 2015, 07:12 PM
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and some OSIRIS images finally online at ESA
http://www.esa.int/Our_Activities/Space_Sc...Comet_close-ups
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