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Europa's Ice May Be Miles Thick
serutan writes "Space.com has an article detailing recent measurements of the shell of ice covering what is believed to be an enormously deep ocean on Europa, which could harbor life. The thickness of the ice -- many times the previous estimate -- poses a major obstacle to sending a lander that would burrow down through it to the water. [Seems like if they could make the probe kinda warm it would eventually sink through any amount of ice.]"
If the probe is kept hot enough long enough it will indeed melt its way through. However, keeping it that hot for that long takes a lot of energy which has to be either carted all the way to Europa or has to be found in situ. A sufficiently large chunk of high-level nuclear waste might do it. Although this suggestion would reduce the waste problem here on earth slightly, I can't see the tree-huggers being very enthusiastic.
An alternative approach might be to punch through in one explosive event. Steer an appropriately sized cometary nucleus into Europa, wait for things to settle down a little and then dive into the relatively thin and slushy crater floor.
Paul
Lasciate ogne speranza, voi ch'intrate
Given an infinite amount of heat energy, sure. But if the probe's just "kinda warm", it will merely create a stable pocket of water around itself. The water will never get significantly above 32 degrees (F) ya know.
Eventually the area of the boundary between the liquid pocket and the surrounding ice will be sufficent that you'll be losing heat faster than you're putting it in - unless you are talking a lot more heat than "kinda warm" - the kind of heat we might refer to as "unbelieveably blazing hot consuming titanic amounts of energy".
Hey, how 'bout this: Leave a solar array on the surface, make the submersible part as small as possible (camera, heat elements, and spool of fine wire). Then you can power the heater electrically from a wire you unwind as your blazing hot ice-melter sinks.
You heard it first on Slashdot! (Of course, I *am* a former rocket scientist, so we might be cheating)....
Good idea, but not necessarily. Ice packs tend to be dynamic flows with upwelling, downwelling and lateral movement. Metling say a few meters a day, would still take year or even more to reach the ocean below. In addition, the pressures below the ice pack will be immense once the liquid ocean is reached. Not to mention the giant pod eating monsters that probably lurk there.
Someone you trust is one of us.
Unfortunately, I believe they didn't have too much luck. Their cylindrical probe would only melt the ice right under it. The walls would freeze back into place and hold it with friction (since ice expands, and as such would create pressure on the hull). I wonder if they would have been more successful with a raindrop-shaped design, where the pressure from the refreezing ice would actually help propel it downward. In any case, the high pressures involved would probably crush any payload.
The other problem was how to relay any information it harvested back to the surface, so it could be retransmitted to Earth. H2O blocks most radio waves pretty well, and stringing a wire all that distance suffers similar problems as the probe itself -- you'd have to keep it hot to keep moving.
Until then, we'll just have to rely on remote sensing...
The cracks once formed last for many many years. I don't offhand remember how many millenia they last for. But they are easily visible and well mapped. The crack forms, the water freezes over, but (the article argues) water should be forced into the crack due to tidal forces. Eventually, the crack will seal up but as I said it would take a long time.
Anyway, sounds like it's worth a shot.
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