The First Europa Lander, What can be done first, cheapest & best? |
The First Europa Lander, What can be done first, cheapest & best? |
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![]() Merciless Robot ![]() ![]() ![]() ![]() Group: Admin Posts: 8784 Joined: 8-December 05 From: Los Angeles Member No.: 602 ![]() |
I think that many people in this forum would agree that somebody's going to have to land on Europa someday before the rather elaborate schemes to penetrate the outer ice layer will ever fly, if for no other reason than to get some relevant ground truth before committing to such an elaborate, expensive, and risky mission.
EO seems to have ruled out any surface science package for that mission (though it would be nice to change their minds! ![]() 1. A sonar transducer/receiver set embedded within a penetrometer to determine crust density and examine the uniformity of the ice layer within the operational radius of the instrument (looking for cracks and holes, in other words). 2. A conductivity sensor again embedded inside a penetrometer to measure the native salinity of the surrounding material and possibly derive some constraints on the composition of metallic salts in the European crust (saltiness has a major effect on ice properties, in addition to the obvious need to derive the salt content of any underlying ocean). 3. A seismometer for all sorts of reasons. How does this sound? Any critiques, additions, or subtractions? I omitted a surface imager not only because of bandwidth/extra complexity considerations but also because it seems desirable to penetrate the crust in order to minimize as much as possible reading any contaminants from Io during surface measurements. The orbiter data could be used to sense and subtract this from the penetrometer readings. -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Member ![]() ![]() ![]() Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 ![]() |
Your point on impurities lowering the melting point is well taken. However I don't think sublimation will have any effect on the energy required. The melting will happen in a thin water film around the probe and I can't see how sublimation could work in this environment. There may be some sublimation behind the probe if the hole stays open, but that does not do you much good. Also the ice is actually going to be a lot colder than 173 K at least to start with. Another complication is that several of the (at least) 12 phases of ice may be present at depth on Europa, and I'm very uncertain how this would affect the energy requirements and how they would react to heating.
As for the surface relay being fried by radiation, how about this: the complete probe lands on Europa and deploys a dumb rad-hardened antenna that anchors itself to the surface (easy, you turn on a little heater in each leg for a while, and then turn it off again). Then the complete probe starts melting itself into the ground unwinding the antenna cable. When it has gone several meters into the ice the probe separates into two parts. The relay section (which has a small (or well-insulated) RTG) freezes into place while the deep-sinker section with a big, hot RTG keeps on going down and unwinding either a thin metal wire or a an optical filament to keep in contact with the relay. Note that the bobbin must be on the sinker since the filament will inevitable get frozen in. Using a long thin wire for communication may sound outlandish, but both missiles and torpedoes use this kind of wire for guidance over very considerable distances (tens of kilometers) and at very high speeds. The Swedish Navy even has a variety of the TP61 torpedo that can be used for reconnaissance/intelligence gathering. A submarine launches it and then lies doggo on the bottom while the torpedo runs in slowly and quietly towards e. g. a harbor. Then the torpedo also puts itself on the bottom and starts listening and sends what it hears back through the wire quite indetectably. The main problem with using wire communication is that if there is much internal movement in the ice it will probably break the wire. However the amount of movement in ice can be determined seismically, so in addition to measuring the thickness of the ice and the composition, we will need to land at least one seismometer on Europa. |
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