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, 09:25 PM
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Member Group: Members Posts: 706 Joined: 22-April 05 Member No.: 351 |
I stole a little time at lunch to compare camera resolutions. Note: I simply took quoted resolutions at specified distances from public websites and normalized resolutions to 1,000 km distance. View these as approximations.Attached file should preserve table formatting.So with that, here is how the high resolution/narrow angle cameras from various missions would compare at set distances: 1K km 10K km Ganeymede to: Jupiter Io (closest) Io (furthest) Web quoted resolutionJSO 2 m 20 m 2.1 km 1.3 km 3.0km 0.4 m at 200 kmEE 10 m 100 m 10.7 km 6.5 km 14.9 km 1 m at 100 kmCassini 6 m 60 m 6.4 km 3.9 km 8.9 km 0.024 m at 4 kmMRO 1 m 10 m 1.1 km 0.6 km 1.5 km 0.3 m at 300 kmDeep Impact 3 m 30 m 3.1 km 1.9 km 4.3 km 2 m at 700 kmPage 3-5 of the JSO report says that the 0.5 m optics chosen as a baseline could achieve an optical resolution of 775 m from the distance of Ganymede, which is considerably better than is in my chart here. The difference could be caused by (1) a loss of resolution between theoretical optics and what is achieved with an actual CCD implementation (2) I don't know what I'm doing in putting together this chart. Caveat emptor! I stole a little time at lunch to compare camera resolutions. Note: I simply took quoted resolutions at specified distances from public websites and normalized resolutions to 1,000 km distance. View these as approximations.Attached file should preserve table formatting.So with that, here is how the high resolution/narrow angle cameras from various missions would compare at set distances: 1K km 10K km Ganeymede to: Jupiter Io (closest) Io (furthest) Web quoted resolutionJSO 2 m 20 m 2.1 km 1.3 km 3.0km 0.4 m at 200 kmEE 10 m 100 m 10.7 km 6.5 km 14.9 km 1 m at 100 kmCassini 6 m 60 m 6.4 km 3.9 km 8.9 km 0.024 m at 4 kmMRO 1 m 10 m 1.1 km 0.6 km 1.5 km 0.3 m at 300 kmDeep Impact 3 m 30 m 3.1 km 1.9 km 4.3 km 2 m at 700 kmPage 3-5 of the JSO report says that the 0.5 m optics chosen as a baseline could achieve an optical resolution of 775 m from the distance of Ganymede, which is considerably better than is in my chart here. The difference could be caused by (1) a loss of resolution between theoretical optics and what is achieved with an actual CCD implementation (2) I don't know what I'm doing in putting together this chart. Caveat emptor!
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