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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#1
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Member Group: Members Posts: 540 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 28 2015, 09:45 AM
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#2
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
Three views, and musings, of "Tall Mountain", Ceres
Exaggerated View https://univ.smugmug.com/Dawn-Mission/Ceres...enh4--ref-L.png Relief and Elevation Maps https://univ.smugmug.com/Dawn-Mission/Ceres...rt--annot-L.png First HAMO image https://univ.smugmug.com/Dawn-Mission/Ceres...t-N--enh1-L.png --Bill -------------------- |
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Aug 28 2015, 05:31 PM
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#3
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Junior Member Group: Members Posts: 21 Joined: 30-June 15 From: Brooklyn NY Member No.: 7543 |
Let me go out on a limb on the lonely mountain. If this is an uplifted feature, I've been puzzled by the lack of debris around the base. Now that I'm looking more carefully, I see relatively fewer small craters around the base to the North and East (12-4 o'clock), especially between the mountain and the crater (12-2 o'clock). There is obvious flow INTO the crater (11 o'clock). And to the Northwest and West, perhaps what looks like a splash or flow (11-9 o'clock). What if the Northeastern half of the mountain lifted first? The ice (?) interior was exposed as the regolith sloughed off. By this interpretation, the Southwestern quarter of the mountain has uplifted more recently, carrying its cratered surface with it. The regolith has not yet sloughed away. I see no sign of debris flow (yet) there, around the base of the mountain (~9-4 o'clock). Alternatively, the lonely mountain results from a single uplift event, but for whatever reason the rake of the NE half was steeper -- causing the powdered regolith to slough away there. |
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Aug 29 2015, 11:10 AM
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#4
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
@MarsInMyLifetime: The "Little Prince's volcano." Cute name for the mountain. That's why I am advocating that this feature be named Saint-Exupéry, even though it seem less likely that it might be an actual volcano.
.... Now that I'm looking more carefully, I see relatively fewer small craters around the base to the North and East (12-4 o'clock), especially between the mountain and the crater (12-2 o'clock). There is obvious flow INTO the crater (11 o'clock). And to the Northwest and West, perhaps what looks like a splash or flow (11-9 o'clock). What if the Northeastern half of the mountain lifted first? The ice (?) interior was exposed as the regolith sloughed off. By this interpretation, the Southwestern quarter of the mountain has uplifted more recently, carrying its cratered surface with it. The regolith has not yet sloughed away. I see no sign of debris flow (yet) there, around the base of the mountain (~9-4 o'clock).... Yes I also noted that there's craters on part of the mountain slope, but not on the other sides, so yes also I wondered if it might one unusual pingu like iceplug that first tilted up on one side, and then on the other to give that appearance. But since I am unable to even find a speculation why it should behave that way I left that idea rest here, until you now mentioned it. So yes it's a possibility, but until someone can come up with a example of such a stepwise behaviour I will go with the idea that it is a single event that created the mountain and that we simply see crust material that happened to stick together in those positions. .............The feature definitely continues to look strange. If the white material here was just slightly under a dusting of the grey material, why aren't we seeing it where this more rectangular edge is located? As I recall from the animations I did of this spot from the survey orbit images, the crater just south of of the rayed crater, is another uplifted mound with a large crater at the top. The craters with the white flecks always seem to have very sharply definitely edges and steep walls. I'll be very interested to see Spot 1. I agree it is odd, unless the white material is salts, and the crack happened to contain a splinter of ice brought closer to the surface by the impact that sublimated afterwards. (This means that that crater could have more ice on adjacent sides that simply happened to have more ice that just got it lucky by being covered by more regolith / asteroid dust material - only said as one possible solution to what we're seeing here.) |
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