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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Mar 25 2008, 11:25 AM
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Member Group: Members Posts: 118 Joined: 18-November 07 Member No.: 3964 |
In general, the LaPlace instruments weigh much less than the Europa orbiter instruments. In general, that means less capable science but lower development and testing costs, lighter spacecraft, cheaper launcher, smaller power supply, cheaper operations, etc... I think that we get outer planets missions so rarely and they are so expensive, that "less capable instruments" would actually be a waste of resources. |
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Mar 25 2008, 11:40 AM
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
I think that we get outer planets missions so rarely and they are so expensive, that "less capable instruments" would actually be a waste of resources. This is my opinion as well. I think we should try and cram as much science onto a single spacecraft as possible (similar to what Cassini did), not send "mediocre" instruments. If that requires several international partners, then by all means go for it. Better than sending virtually empty spacecraft buses on billion km voyages just so we can lower the price and be able to say "we've got an orbiter right there". -------------------- |
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Mar 26 2008, 12:25 AM
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Member Group: Members Posts: 715 Joined: 22-April 05 Member No.: 351 |
.. not send "mediocre" instruments the instrument weights proposed for LaPlace are in the class of instruments that New Horizon is flying. If you can get close to your target, they are fine (with caveat below). At Jupiter, though, getting close to Io and Jupiter comes with a significant radiation problem, so you'd like to have much larger optics on your instruments. New Horizons did some nice work during its flyby, but there's a strong desire for much higher resolution, even for a monitoring program. Now the caveat: Heavier instruments also typically have more sensitivity and more measurement modes. The instrument can deliver (weight) to the target and afford is better than the one that fails both criteria, though. The $2B version of the Europa orbiter cut both instruments and instrument capabilities to get development costs and weight down, and reduce the overall mission cost from $3B. -------------------- |
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