Ceres High Altitude Mapping Orbit (HAMO), Late summer through fall 2015 |
Ceres High Altitude Mapping Orbit (HAMO), Late summer through fall 2015 |
Aug 17 2015, 01:42 AM
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#16
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Member Group: Members Posts: 541 Joined: 17-November 05 From: Oklahoma Member No.: 557 |
DAWN arrived in its new lower mapping orbit on August 13th. The DAWN team is preparing to resume science observation tomorrow on the 17th.
From the Current Mission Status page at the DAWN website: QUOTE August 13, 2015 - Dawn Arrives in Third Mapping Orbit
Dawn completed the maneuvering to reach its third mapping orbit and stopped ion-thrusting this afternoon. This was a little ahead of schedule because the spiral descent went so well that some of the allocated thrusting time was not needed. Since July 14, the spacecraft has reduced its orbital altitude from 2,700 miles (4,400 kilometers) to approximately 915 miles (1,470 kilometers). The orbit period has correspondingly decreased from 3.1 days to 19 hours. Dawn is scheduled to begin its new observations on the evening of Aug. 17 (PDT) and continue for more than two months. First, however, the mission control team will measure the actual orbit parameters accurately and transmit them to the spacecraft. |
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Aug 29 2015, 01:33 AM
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#17
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Bill, you posted that exactly as I was bringing the thread up to post the same thing. These craters may be impact-formed, but if so, the target material has far different properties from what we've seen on rocky worlds, and also far different from what we've seen on icy worlds farther out from the Sun. Some of these flows look more like they were blurped onto the surface, not thrown as ejecta or erupted as volcanic units. More like a they were vomited onto the surface.
I wonder how much difference it makes that Ceres is too close to the Sun for the exposed ices to completely resist sublimation, yet too far from the Sun for a world with so much water to be primarily rocky. We're in a different thermal environment for a watery world than we've seen before. Perhaps that's what is driving the strangeness we're seeing in the surface features. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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