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, 07:24 PM
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
LOL Yeah, that's a good point to keep in mind, we aren't just talking about EE and JSO, but Enceladus and Titan as well. As I said before, I don't think we can make a decision on whether Enceladus needs a flagship mission just yet. I think by the end of the Cassini mission, the question of the source of the jets will largely be answered. If they come almost directly from a liquid water source, then Enceladus jumps ahead of Europa quite frankly. Why send 2 or 3 missions to sample potential life when you can send one If the jets do come from a liquid water source, we have the trifecta: liquid water, organic molecules, and an energy source, and the reservoir can be sampled MUCH more easily than at Europa (assuming we can capture this material on a Stardust-like pass and bring it back to Earth). If the jets don't come from a liquid water source, then frankly, Cassini's coverage at Enceladus should be quite sufficient by the end of the extended mission.
As for Titan, I think the kind of science that can be done at that one target would be far more exciting, frankly, than Europa. Not as diverse as JSO, though. Hense my earlier ranking of: 1) JSO, 2) Titan Explorer, 3) Europa. Enceladus could be #1 if the jets come from a liquid water source, #4 if they don't. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
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