Composition Of Outer Satellite Ices, What are Jupiter's moons made of? |
Composition Of Outer Satellite Ices, What are Jupiter's moons made of? |
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 ![]() |
Paper: astro-ph/0510798
Date: Fri, 28 Oct 2005 10:23:28 GMT (316kb) Title: Modeling the Jovian subnebula: II - Composition of regular satellites ices Authors: Olivier Mousis and Yann Alibert Comments: 9 pages, A&A, in press \\ We use the evolutionary turbulent model of Jupiter's subnebula described by Alibert et al. (2005a) to constrain the composition of ices incorporated in its regular icy satellites. We consider CO2, CO, CH4, N2, NH3, H2S, Ar, Kr, and Xe as the major volatile species existing in the gas-phase of the solar nebula. All these volatile species, except CO2 which crystallized as a pure condensate, are assumed to be trapped by H2O to form hydrates or clathrate hydrates in the solar nebula. Once condensed, these ices were incorporated into the growing planetesimals produced in the feeding zone of proto-Jupiter. Some of these solids then flowed from the solar nebula to the subnebula, and may have been accreted by the forming Jovian regular satellites. We show that ices embedded in solids entering at early epochs into the Jovian subdisk were all vaporized. This leads us to consider two different scenarios of regular icy satellites formation in order to estimate the composition of the ices they contain. In the first scenario, icy satellites were accreted from planetesimals that have been produced in Jupiter's feeding zone without further vaporization, whereas, in the second scenario, icy satellites were accreted from planetesimals produced in the Jovian subnebula. In this latter case, we study the evolution of carbon and nitrogen gas-phase chemistries in the Jovian subnebula and we show that the conversions of N2 to NH3, of CO to CO2, and of CO to CH4 were all inhibited in the major part of the subdisk. Finally, we assess the mass abundances of the major volatile species with respect to H2O in the interiors of the Jovian regular icy satellites. Our results are then compatible with the detection of CO2 on the surfaces of Callisto and Ganymede and with the presence of NH3 envisaged in subsurface oceans within Ganymede and Callisto. \\ ( http://arXiv.org/abs/astro-ph/0510798 , 316kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Guest_BruceMoomaw_* |
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There has already been a lot of interest in a solar-powered Trojan flyby mission -- maybe even one that flies by more than one Trojan -- which could very likely be made within the Discovery cost cap. Beth Ellen Clark of Cornell was associated with one such Discovery proposal called "Andromache", although it's hard to find anything on it.
But: there is also now a proposal floating around -- neat acronym and all -- to actually have a New Frontiers-class craft orbit one or maybe even two Trojans. It's called PARIS; it would use the new concept of a low-powered but long-duration ion drive powered by a particularly large 1-kilowatt RTG (which must use the new, more efficient future RTG designs to reduce its plutonium load); and there have already been at least two abstracts on it, the most recent being at http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1922.pdf . (This new type of propulsion system is attracting increasing interest; it would apparently also allow a relatively low-cost giant planet orbiter which could do an awful lot of putt-putting around the planet's system of moons -- including orbiting one or more of them -- after the orbiter was initially braked into orbit around the planet by aerocapture.) |
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