Dawn's Survey Orbit at Ceres |
Dawn's Survey Orbit at Ceres |
Jun 15 2015, 05:47 PM
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#16
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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, 12:37 AM
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#17
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Newbie Group: Members Posts: 1 Joined: 15-June 15 Member No.: 7505 |
Newby here. I can construct a hypothesis for the bright spots by taking pieces of the various ideas posted in this thread. 1) Ceres has salts on or very near the surface, which are left over from a time when it was warmer and spewing water/salt mixtures over the surface. 2) Over time, the salts darken upon exposure to radiation. 3) There are occasional impacts into the surface which cause localized heating. If I couple these with the observation that radiation-darkened salt can be bleached back to white upon exposure to heat, then that might explain the distribution of these bright spots. Explicitly, occasional impacts warm the surface, bleaching the ice back to its brighter, higher albedo form until it darkens back over time. The salt deposits would have been preferentially deposited in the lower areas like crater basins, but would otherwise appear sort of randomized, due to the random impacts coming in.
Here is a somewhat relevant reference: http://www.sciencedirect.com/science/artic...19103579901702# I also read a bit that sunlight can bleach some salts back to being bright, but could it be that Ceres is too cold or far from the sun for that to dominate the radiation induced darkening? Anyway, that's my utterly amateur guess. |
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Lo-Fi Version | Time is now: 14th June 2024 - 10:33 AM |
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