Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
Jan 12 2015, 12:10 AM
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Solar System Cartographer Group: Members Posts: 10226 Joined: 5-April 05 From: Canada Member No.: 227 |
On Tuesday (two days from now, for visitors from the future), the first optical navigation image will be taken... hopefully we'll have it in our hands soon after that. So it's time for a new topic. Over the next few months we'll have progressively closer images and full orbit characterization sequences, no doubt including multispectral image sets.
A new world... This is a bit of reprocessing I have been doing with the Hubble images from a few years ago. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Feb 13 2015, 11:11 PM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Statistically, if other cratered bodies are anything to go by, there should not be a dichotomy in terms of what portions of Ceres were hit by large impactors and what portions were not. I think one thing that is fooling us right now is that the lower half of the disk we see is at a lower sun angle, and thus shows more relief. The northern half may be nearly as heavily cratered as the southern, just washed out due to more overhead lighting in these images.
Also, a lot of the "smoother" terrain, even in the southern portion of the images, looks a little to me like basin floors, which may well end up smoothing themselves out more than ringwalls thrown up by large impacts. It's tremendously exciting to know the resolution will improve an awful lot over the next week or two! -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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Feb 14 2015, 10:25 AM
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Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
Statistically, if other cratered bodies are anything to go by, there should not be a dichotomy in terms of what portions of Ceres were hit by large impactors and what portions were not. I think one thing that is fooling us right now is that the lower half of the disk we see is at a lower sun angle, and thus shows more relief. The northern half may be nearly as heavily cratered as the southern, just washed out due to more overhead lighting in these images. Also, a lot of the "smoother" terrain, even in the southern portion of the images, looks a little to me like basin floors, which may well end up smoothing themselves out more than ringwalls thrown up by large impacts. I don't think either that such a dichotomy would make much sense (although e.g. Enceladus does not seem that terribly far away from having one (in terms of being cratered); and it does have one when comparing the poles specifically). But I don't see how the sun angle could explain how the apparent cratering changes with latitude and longitude both, like it does in the images. There really does appear to be some sort of transition(s) going on near the equator, indeed perhaps into basins. It might be that there are just small strips of terrain that have a slightly different topography (and that the north and south are mainly the same), but I feel confident that either the 12 Feb or 19 Feb images will vindicate my view that there is something (potentially quite trivial) going on there. Indeed, there is just 5 days until the 221 pixel global images of 19 Februrary are taken; that date should be marked as a milestone for the exploration of the solar system. -------------------- |
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