Maybe it's my own peculiar variant of pareidolia, but every time I see a new image of Vesta I'm reminded of some different other lumpy body in the solar system. In the image released just now by the Dawn team, taken from 10,500 kilometers away, I'm seeing Hyperion. First, here's the new Vesta image:
NASA / JPL-Caltech / UCLA / MPS / DLR / IDA
Vesta on July 18, 2011
And here is a typical Hyperion image. I guess they're not that similar. But I suppose it's natural to try to fit something totally new into the neat little cubbies that already exist in my brain -- until Vesta once and for all shows me that it's a unique world, deserving of its own home in my mind.
After making quite an annoying pest of myself to the Dawn team (and I'm sorry about that) I understand a bit better what's being done to the images before they're posted. The most useful piece of information I've gotten is that the images are actually being enlarged by whole-number factors before posting. There's still some weirdness with the size of Vesta in the images -- either the information about the range from Dawn to Vesta or the expected size of Vesta, based on relatively low-resolution Hubble images is not quite right. If the former, a correction will no doubt be issued somewhere down the line; if the latter -- well, that would be a very interesting scientific result, to learn that Vesta is not the size that we thought it was!! I did some more math, though, and Vesta appears larger than expected in two of the three most recent images, and smaller than expected in one of them, so my inclination is that it's the ranges that aren't quite right. I had to be reminded that this is not a smoothly coasting chemically powered mission, it's an ion-powered spacecraft whose orbit is continuously changing, so it's a significantly more complicated task to figure out exactly where it was in space -- and consequently how far it was from Vesta -- at any given moment.
Now that I know how the images have been enlarged, I can shrink them to their original resolution. Why would I want to do that? So I can get the movie I've been wanting: I want the ship's eye view of Vesta, bulking larger and larger out the metaphorical windshield as the spacecraft creeps ever closer. Here you go, for a ride along with Dawn:
NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / animation by Emily Lakdawalla
Approaching Vesta (as of July 18, 2011)
This animation is the size of the field of view of Vesta's camera, and shows the images released to date at approximately their original resolution. Each passing day gives Dawn more detail on the surface of the asteroid.
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