OPAG Reports, Formal proposals/evaluations of future outer SS missions |
OPAG Reports, Formal proposals/evaluations of future outer SS missions |
Nov 9 2007, 08:28 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
http://www.lpi.usra.edu/opag/announcements.html
That's one little URL with a lifetime's worth of reading material. Three detailed studies are available in PDF format. The missing body is Titan, which will be the subject of a forthcoming report. The three focus missions are: Europa Explorer: Fairly detailed description of a mission that is pretty much what Europa Orbiter would have been. Jupiter System Observer: Basically, Galileo 2 (without the antenna mishap!). The craft would start with a 3-year tour of all the Galileans, then spend 1 year in an elliptical Ganymede orbit, then the rest of the mission in a tight, polar Ganymede orbit (like MGS at Mars). That would map the heck out of Ganymede, but also be close enough to the rest of the system to make long-range observations for years. Note that Ganymede would thereby provide a lot of radiation shielding. Enceladus: where three profiles are examined in depth: Enceladus Orbiter only; Enceladus Orbiter with soft lander; Saturn orbiter with Enceladus soft lander. There's more to chew on here than I have had (or may ever have) time for, but I'll throw in my two cents' worth: Seems like a Europa-only mission would only benefit from coming after a JSO. EE would explore Europa much better than JSO would; why even have JSO observations at Europa if EE came first? In many ways, these two missions are competitive. EE would have the big payoff, but JSO seems like basic recon that would prime EE, especially giving specs on radar performance. But if we waited til JSO was 4 years into its mission before completing design of EE, then put EE sometime mid-century. If an Enceladus mission included a Saturn orbiter, then maybe the same orbiter could provide data relay for separate Titan elements. However, a lot of the Enceladus science goals would require an Enceladus orbiter, so I don't think a Saturn orbiter for Enceladus/Titan will win out. Note that Enceladus orbital velocity is low enough that the craft could manage to take lots of hits from ice pellets and survive. Put a bulletproof vest on the craft and let it soar through the plumes endlessly. |
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Nov 20 2007, 05:45 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
This discussion is interesting in that it seems to reduce the question down to whether or not Europa alone is intrinsically more interesting than the rest of the Jovian system.
I have to agree with Jason -- I think that, given a choice between the JSO and EE mission profiles, I like the JSO better because it gets most (if not all) of the data you need about Europa to plan the next mission, and gives you a lot more data about the rest of the system than EE would. Recall, please, that some Galileo results suggest that Ganymede and even Callisto may have "molten ice" (i.e., liquid water) mantles below their solid ice crusts. Granted, Europa is the most interesting from an astrobiology perspective (more access to sunlight and tidal heating), but any body with a hard ice crust and a liquid water mantle can teach us an awful lot about such worlds. And it may be a very good idea to learn about them -- it's always possible that there are more habitable worlds of the Europa type out there than there are of the Earth type. After all, a Europa could form around pretty much any gas giant in a huge expanse of a solar system's domain, while an Earth has to reside in that narrow little Goldilocks band. Statistically speaking, you might expect more life to arise in Europa-like worlds than on Earthlike worlds, just from sheer numbers. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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