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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Mar 15 2014, 09:42 PM
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Because the ice crust may be recycled over reasonable scales of time, or a given spacecraft may hit the jackpot & impact a surface weak spot…stuff like that. Bottom line is that we really don't have a great handle on Europa's ice crust dynamics as yet, nor if there even really is an ocean underneath…too many unknowns. Therefore, the smart move is to be extremely cautious.
-------------------- 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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Mar 16 2014, 06:26 AM
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#3
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Member Group: Members Posts: 202 Joined: 9-September 08 Member No.: 4334 |
Because the ice crust may be recycled over reasonable scales of time, or a given spacecraft may hit the jackpot & impact a surface weak spot…stuff like that. Bottom line is that we really don't have a great handle on Europa's ice crust dynamics as yet, nor if there even really is an ocean underneath…too many unknowns. Therefore, the smart move is to be extremely cautious. Ah, OK, thanks... I just had seen stuff making it sound like it would be incredibly difficult to get through the ice intentionally (eg drilling lander) so it seemed like kind of a disconnect. When you say recycled over reasonable scales are you talking millions of years (short compared to the age of the moon itself) or something much shorter? |
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Mar 16 2014, 02:26 PM
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#4
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
The age of Europa's surface is approximately 60 MYa. If we naively assume that it's being recycled systematically, one bit at a time, then you'd expect an object on the surface to go subsurface after an average of 30 million years. But if you shattered a space probe into many pieces, and you happened to hit a general region that was on the "short list" for subduction in the near future, and moreover the object was dark and metallic, so hotter each day than the ice around it, it might get subsurface faster.
To be clear, I don't think we'd likely have a crashed orbiter get into the ocean very soon with any great probability, but an ocean is exactly the sort of thing you *really* won't want to risk contaminating because of potential global mobility over short time scales. |
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