Dawn's Survey Orbit at Ceres |
Dawn's Survey Orbit at Ceres |
Jun 15 2015, 05:47 PM
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#1
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
daily Ceres picture from the survey orbit
http://dawn.jpl.nasa.gov/multimedia/images...tml?id=PIA19572 I started a new topic, as we are no longer in the first orbit phase |
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Jun 24 2015, 04:50 PM
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#2
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Junior Member Group: Members Posts: 59 Joined: 25-December 05 From: Stevens Point, Wisconsin, USA Member No.: 619 |
"....low energy/velocity impactor theory... with maybe the impactor actually being a rubble pile..."
...If that's the case, why didn't we any white spots on, say, Vesta? |
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Jun 24 2015, 05:26 PM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Some qualitative thinking where computational modeling would be required, but:
If Ceres had a significant subsurface H2O aquifer at some point in the past when it was relatively warmer, and then cooled, then the expanding ice had to go somewhere. Globally, this would cause extension if the stress were applied equally everywhere, but violent venting seems like another apt outcome. There would be subsurface water with ice atop it, the ice layer thickening but subject to the weight of the crust above it. Where it vented, there could be tremendous lateral flow to draw from the water layer worldwide, continuing the eruption for quite some time. The water blasting out at the surface would probably undergo a lot of evaporation and loss into space, although perhaps it could have caused a significant temporary atmosphere. What didn't escape could have caused monumentally large accumulations of ice on the surface. Maybe what we're seeing is the result of a relatively small number of such eruptions, which eventually let out all of the excess pressure caused by the expansion of freezing H2O. |
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