NASA Europa Missions, projects and proposals for the 2020s Options

[MahFL]

Yahoo News

[Roly]

Many thanks Mcaplinger, this was very interesting to read. That issue of storage seems to always be "very soon now", I seem to remember chalcogenide / phase change and FRAM being promised in the JIMO-era studies. On the trades, does the option of spending much of the time "standing off" at Ganymede with a suitably massive and impressive mirror make any sense? I only ever saw it proposed in those MIDAS slides, and they were build around what seemed to be special optics.

[mcaplinger]

On the trades, does the option of spending much of the time "standing off" at Ganymede with a suitably massive and impressive mirror make any sense?

Not to me. Shielding is easier to make than big optics and may well weigh less.

If people want to get some insight into some of the engineering that goes into these sorts of missions, the JUICE proposal information is a good read http://sci.esa.int/juice/ JUICE is actually a fairly good start for a Europa mission, too bad they didn't pick our camera

[TheAnt]

.......too bad they didn't pick our camera

What's in a name, the acronym for the JANUS camera is in Latin: "Jovis, Amorum ac Natorum Undique Scrutator."
Jovis mean Jupiter, Scrutator is nearly the same as the English 'Scrutinise' but after that I had to give up to the meaning.
Italian instrument so the name figures to some degree at least. =)

Related link, as for the selection of instruments DLR are happy to be onboard as well. German page.

[JRehling]

Although it pains me to see Europa exploration further delayed, the situation persists that we're still in search of the right mission architecture for the realities of Europa. Some post-Galileo discoveries, mainly based on analysis of Galileo data, have upended what we might have previously thought would make a good next step.

IMO, given the ability to detect plumes, but an incomplete knowledge of their temporal patterns of occurrence makes planning the next mission an absolute non-starter. If the plumes occur at every apojove, that's one reality to plan for. If they occur at 10% of apojoves, with no apparent pattern, that's another reality to plan for. If in a decade we see them only a few times, that's yet another reality. There is no wise mission design for Europa that precedes this sort of knowledge.

JUICE is planned to wrap up its main mission around 2033. If the idea of waiting for that mission to end before planning the next one doesn't make you wince, you're very young and very patient. Maybe recon from Earth-based/orbiting telescopes can allow us to plan pre-JUICE, but that still calls for at least a couple of years of observations and analysis before we can plan the next step.

Maybe the best bet is to time a free-return plume-sampling mission to arrive when JUICE is active and use JUICE's observations to adjust the outbound trajectory to time a fly-through more favorably. I'm not sure, though, if such an option even makes sense in terms of engineering and orbital mechanics.

The analogy I would use is that if exploring Europa is chess, the plumes are the king. We can make plans for mapping and radar, etc., and focus on the rooks and queen, etc., but getting a sample of the plumes back to Earth is checkmate. If we can play for checkmate, we should.

[vjkane]

The analogy I would use is that if exploring Europa is chess, the plumes are the king. We can make plans for mapping and radar, etc., and focus on the rooks and queen, etc., but getting a sample of the plumes back to Earth is checkmate. If we can play for checkmate, we should.

I rarely disagree with John, but this is one time I will. We don't yet know that the plumes are real. The plume signal was at the edge of detectablity -- much like the measurements of ozone at Mars. Going straight to a sample return mission is premature in my opinion. We don't even have a good idea of particle size or density. If they plumes exist, it does not mean that they are connected to a deep subsurface source -- look at the explanations for the Enceladus plumes that do not require as subsurface ocean. Also, do the plumes occur every orbit or once a decade?

There are excellent reasons for flying a dedicated multi-flyby mission whether or not the plumes exist. The strategy that makes sense to me is a synergistic mission with JUICE. JUICE can do the global studies stand offstudies of the plumes with its UV spectrometer. However, it will be limited to a small number of flybys within a narrow range of Jovian longitudes. A Clipper-like mission can make many flybys and adjust its Jovian encounter longitude to match the peak plume output (assuming it exists).

I don't think that the discovery of plumes requires that the only mission that now makes sense for NASA is a sample return. In my opinion, do global surface studies as already highly prioritized, map the subsurface of the possible plume region to understand the source, include the mass spectrometer that is already a high priority for in situ measurements, and perhaps also include a dust counter and/or dust spectrometer to give us particle size. Once we understand the nature of the plumes and can place their source in context, we can plan an optimal sample return mission.

Ideally, we'd fly the survey mission this decade and if appropriate the sample return mission the next decade. But I don't agree on NASA doing no dedicated Europa mission until JUICE confirms the nature and sources of the plumes.

[stevesliva]

Ideally, we'd fly the survey mission this decade and if appropriate the sample return mission the next decade. But I don't agree on NASA doing no dedicated Europa mission until JUICE confirms the nature and sources of the plumes.

Especially because you get situations like Titan. Now that we know a lot more about the surface, we seem no more likely to take another more informed look. And the nature of things is not that you can cache goodwill for forgoing a mission opportunity. You take it.