OPAG Reports, Formal proposals/evaluations of future outer SS missions Options

[JRehling]

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.

[nprev]

Does JPL or another agency maintain a launch opportunity "library", by any chance? Seems like the operations research folks should be doing just that: looking for optimal launch opportunities for various targets, and publishing them in order to solicit & align mission proposals with the realities of orbital mechanics.

Reason I ask is that the Galileo & Cassini transit trajectories were pretty complex, and at least in the case of Galileo this was certainly not the preferred option for a variety of other reasons. Seems as if determining all feasible options in this regard would be quite beneficial for future mission planning.

Well, probably just re-invented the wheel here, but given the inherent variability in planetary exploration initiatives just thought I'd ask...

[gndonald]

Does JPL or another agency maintain a launch opportunity "library", by any chance? Seems like the operations research folks should be doing just that: looking for optimal launch opportunities for various targets, and publishing them in order to solicit & align mission proposals with the realities of orbital mechanics.

That's actually how Voyager came about, someone calculated that it would be possible to launch during the 1970's and hit all the major outer planets with one mission then pushed as hard as possible to get that mission flown.

The NASA technical reports server has all sorts of documents related to trajectory planning, one of the more interesting online documents is one written at a time NASA was considering creating a Solar-Ion drive 'common bus' for future space exploration. It covers outer planet opportunities for that type of spacecraft from Jupiter to Pluto for the period 1975-1990. (Download 11.9mb PDF)

One of the offline documents discusses missions that would flyby Saturn for gravity assist purposes before heading on to Uranus, that covered 1979 -1987, the next set of such opportunities will not occur till 2025, so there may be the chance to start a lobbying effort that pays off for the next generation of Space enthusiasts.

[nprev]

That's actually how Voyager came about, someone calculated that it would be possible to launch during the 1970's and hit all the major outer planets with one mission then pushed as hard as possible to get that mission flown.

Yeah, I knew that; wasn't the guy who found that Italian?

What I'm asking is whether there's a dedicated group looking for opportunistic trajectories to the outer planets via possibly complicated inner planet pump-ups, etc. Does not appear to be a trivial effort, but seems as if such a group could generate some real, positive planning data for future outer planet missions.

[Del Palmer]

Yeah, I knew that; wasn't the guy who found that Italian?

Gary Flandro. Not sure if he was Italian or not (thought he was American).