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 21 2007, 04:34 PM
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Having skimmed through these reports (I need to read them more carefully later) I strongly prefer JSO over EE, mainly thanks to its much better instruments, far broader coverage of the Jovian system and longer lifetime once in Ganymede orbit, compared to EE's lifetime in Europa orbit.
Just one close flyby of Io (and in fact there will be four) would return more and higher quality data than all of the Galileo Io flybys combined. There would be high resolution long term monitoring and atmospheric movies of Jupiter at multiple wavelengths, something Galileo couldn't do well because of limited bandwidth and which Voyager, Cassini and NH couldn't do properly due to lack of time. And once JSO is in Ganymede orbit Io can be monitored at 1-2 km/pixel for a long time. It is true that EE would return a lot more Europa data - still JSO's Europa data would be vastly superior to the Galileo data. However, there will be a lot less data for everything else. And let's not forget that Ganymede is interesting. Not as interesting as Europa but still interesting. That said, my 'post-Cassini' view is that I find the Saturn system more interesting than the Jupiter system. Before Cassini I expected the Jupiter system to be more interesting but Cassini has revealed a huge amount of interesting things. |
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Nov 21 2007, 05:21 PM
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
Before Cassini I expected the Jupiter system to be more interesting but Cassini has revealed a huge amount of interesting things. Saturn does have some quirky little moons that Cassini has been able to take a close look at. Are Jupiter's small moons really devoid of the same interesting variety, or is it that we have not looked at them close enough to reveal their quirks? Could there be hidden gems among them, puzzles like Enceladus' plumes, Iapetus' equatorial ridge, or Hyperion's spongy look? Or have we seen enough already to know that no such surprises await a closer look? |
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Nov 21 2007, 05:40 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Saturn does have some quirky little moons that Cassini has been able to take a close look at. Are Jupiter's small moons really devoid of the same interesting variety, or is it that we have not looked at them close enough to reveal their quirks? Could there be hidden gems among them, puzzles like Enceladus' plumes, Iapetus' equatorial ridge, or Hyperion's spongy look? Or have we seen enough already to know that no such surprises await a closer look? Jupiter doesn't have any/many mid-sized moons, which is where most of the surprises have been coming from at Saturn. From what we've seen of smaller worlds, there's less opportunity to surprise. We won't know til we look, but exploring many of those outer jovian satellites would be tough with just one craft. Lots of empty space and wacky orbits out there. You would either need to burn a lot of propellant or have lots of little mini-craft zipping around. |
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