Rosetta scientific results |
Rosetta scientific results |
Sep 12 2014, 03:33 PM
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
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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Dec 10 2014, 08:39 PM
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#2
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
just out and already making noise on the social networks:
67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio QUOTE 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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Dec 11 2014, 04:47 AM
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#3
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Member Group: Members Posts: 102 Joined: 8-August 12 Member No.: 6511 |
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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Dec 11 2014, 06:36 AM
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#4
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Junior Member Group: Members Posts: 41 Joined: 11-April 07 From: London, U.K. Member No.: 1957 |
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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