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: 10182 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 PD: 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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Jan 20 2015, 04:43 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
These images, and especially the animation made from them, do give the impression of a cratered body. In much the same way that the early Mariner 10 images gave the impression of a cratered Mercury -- very suggestive, but not enough to say for sure.
Of course, we would most definitely expect Ceres to be cratered -- with no tidal "pumping" I can't conceive of a heat source (internal or external) that would result in ongoing re-surfacing, and every other airless body that lacks an internal heat source (i.e., pretty much all of them except Io, and to a lesser extent Europa and Enceladus) that we've looked at in our solar system has been heavily cratered. Even Enceladus has some heavily cratered terrain far away from its active plumes. It would be the scientific discovery of the decade were Ceres not heavily cratered. The one nice thing we can say is that we don't have very long to wait, in the overall scheme of things, to get a much better look at this dwarf planet. The Hubble suggestions of an almost Mars-colored world have had me intrigued for quite some time. Now we are very near to knowing, if not the whole truth of the matter, then at least enough data to raise questions we don't even know enough to start asking yet. -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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Jan 20 2015, 05:08 PM
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#3
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
The Hubble suggestions of an almost Mars-colored world have had me intrigued for quite some time. Now we are very near to knowing, if not the whole truth of the matter, then at least enough data to raise questions we don't even know enough to start asking yet. The orange material on the surface that is of huge interest to some of us, though it might have been somewhat changed by sunlight and radiation, it might be quite more pristine than the material we have gotten a glimpse of at Titan, which is heavily reprocessed. QUOTE Habukaz: Could not Ceres having formed "alone" compared to the icy satellites of the gas planets who formed right next to giants have an impact on, say, local distribution of radioactive isotopes (and heavier elements in general)? It is the current thinking that a world like Ceres indeed formed on its own, the question is how it is related to the other large asteroids. Were those once more similar to Ceres in the past? And lost their surface layers by collisions, which Ceres simply were lucky to escape. Or is Ceres one interloper, that somehow have gotten the orbit circularized in the asteroid belt. I consider the latter less likely, but mentioned for completeness since it has been suggested. Internal heating by radioactive decay is of course possible, but remember this is a miniature world, and after aeons after formation the activity would be very low with correspondingly rather little heat. There have been some suggestion that serpentinization of minerals might be a heat source that could keep water liquid close to the core. I am personally pessimistic, but for DrShank's and his colleagues sake I hope to be proven wrong, it could make his work more interesting. =) And thank you all who posted images of the first glimpse of one intriguing little world. =) |
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