NASA Europa Missions, projects and proposals for the 2020s |
NASA Europa Missions, projects and proposals for the 2020s |
Mar 5 2014, 12:53 AM
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Forum Contributor Group: Members Posts: 1374 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
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May 27 2015, 04:59 AM
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#2
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Well, think about it. If you're prospecting for the best places to melt through the ice down into the Great Ocean, you need to characterize the surface on a global scale. You can't run your ice-penetrating radar and sounding radar globally, so you have to have good enough photo coverage to match visual characterizations to the deep-structure information you get slices of from those lower-resolution, more limited coverage instruments. Then you can apply those matches to figure out all of the good potential ocean entry points, where the ice crust is the thinnest.
I would be really surprised if there aren't good visual cues in the high-resolution images of the surface that correlate to the thickness of the crust beneath. It might take some analysis, and the cues might be subtle. Bit I bet we'll find them. Now, this all makes sense if you're using the next mission to plan your assault on the Great Ocean with a melting probe. If you're planning on bringing your melting probe with you on this next flight, well -- good luck finding a good, thin-crust spot to land it on within your mission timing constraints. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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May 27 2015, 11:15 PM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Keep in mind that there are at least two different kinds of sub-surface water hypothesized:
1) The global ocean. 2) Lakes which are melt-lenses and may never have had direct contact with the global ocean. The ferocious debate over the thickness of the crust may be due to the apparent contradictions created by these two distinct phenomena. Just as, once upon a time, people about the nature of nebulae, before finding out that there are several very different kinds of nebulae, the surface phenomena indicating subsurface liquid may have gotten scientists arguing because some phenomena were produced by (1) and some were produced by (2). If so, we can virtually forget about direct probing of (1) anytime soon, but the depth down to (2) may be arbitrarily small at any given time. And then the possible pathways for future surface exploration become quite complex, presenting, for example, trade-offs between the surface units that were most recently in contact with liquid water, the surface units closest to subsurface water at present, and/or the surface units that most assuredly had contact with "dirty" ocean water at some point (however ancient) in the past. As painful as it is to say, we're still at a quite primitive phase in understanding Europa. Mars missions are still surprising us after ≥ half dozen landers and orbiters each. Europa is at the Mariner 9 stage in its exploration, and we're only now planning the second mission after Voyager 2, which can't arrive for another 15 years or so! The next mission there will be, roughly speaking, the Viking Orbiter of Europa (pending any pleasant surprises regarding a lander). This is a deep chess game we're playing with Europa and it's going very slowly. |
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