Dawn Survey Orbit Phase, First orbital phase Options

[ZLD]

As I recall, I don't think it was going to be a large cost component but somewhat intensive in man hours for testing since the type hadn't been flown before, and they were already behind schedule.

[Paolo]

yes, magnetometers on spacecraft are simple devices but they need lots of testing because of the risk of interference from the metallic structure of the spacecraft itself...

[centsworth_II]

There's already a paper Vesta model available!

http://www.koyalwholesale.com/pages-produc...s_6_pieces.html

[tanjent]

I'm just wondering - if the mass in the pre-planetary solar system was concentrated into a disk, how is it possible for a body like Vesta to get smacked in the South Pole? If the impact site was at the south pole prior to the hit, then the impactor would have to have come from outside the ecliptic. If the impact site was not at the south pole before the impact, how could the impact have re-oriented things to put it there?

[nprev]

Gotta remember that the 'disk' was undoubtedly millions of km thick at least, first of all. Also, I'm sure that the early Solar System was pretty chaotic indeed, with lots of stuff bumping into each other quite often, and frequently at oblique angles to boot. It's not beyond the pale at all to postulate a medium population of out-of-ecliptic bodies in the inner Solar System back in the day.

And, of course, it could have been a long-period comet. Those things often have quite funky orbits indeed.

[Hungry4info]

Given two orbits that are inclined only by a degree or two of each other, if the two meet where the orbits intersect, from each body, the other will appear to be approaching from outside the ecliptic plane.

This quick drawing shows the orbits of two bodies with small inclinations, with a polar collision where the two meet.

Attached thumbnail(s)

 

[Paolo]

If the impact site was not at the south pole before the impact, how could the impact have re-oriented things to put it there?

the stable (minimum energy) rotation of an ellipsoid is with the spin axis passing through its shortest axis. so even if the impact was not at the south pole (and it probably wasn't) the stable rotation configuration required the crater to end up at one of the poles

[hendric]

Also, during the early solar system most of your nearby objects would be orbiting in similar orbits with you, and collisions would be relatively low velocity. Two Vesta sized objects hitting each other, for example, would only hit at 2x escape velocity, or about .7 km/sec. Now, once Jupiter migrates inwards, it tends to scramble the orbits of the planetesimals, and so collisions could be between objects with vastly different semimajor axis, ie an object at Vesta could only be passing through due to eccentricity. As H4I shows above, an object with only a slight inclination difference results in essentially a polar hit. Also, it's difficult to tell the angle of the impact using debris except very roughly because of the energies involved, and might not even be possible with an impact of this size.

[algorimancer]

Really disappointing to hear the magnetometer didn't make it onto the vehicle. Considering the nature of Vesta & Ceres, that's quite a loss.

[t_oner]

Here is the simplified Vesta model. I fitted a sphere to the detailed model which even shows the grooves. As we don't yet have geometry information, the polygon lines do not necessarily pass through long/lat lines and poles of the model may not be at the real poles. It is also not to scale.

Attached File(s)

 vesta.zip ( 41.01K ) Number of downloads: 248

 

[chuckclark]

Here is the simplified Vesta model.

Hey -- I can import and open this file in my VectorWorks program!

Thank you, Tayfun.

[tedstryk]

Hey Chuck, looks like you have a new place to apply your mapping technique!

[CosmicRocker]

I took the frames posted by Emily, created anaglyphs from each sequential pair, and assembled them into an animated gif to show the rotating body in 3D. The full sized version is 17 megs. In order to reduce the file size to something that I can upload here I had to reduce the size to 25% and cut the range of colors in half.

The full sized version is much nicer than what I have to post here. I can't find a site that will host a large animated gif. Flickr won't take it and the animation doesn't work on Picasa. If anyone has any suggestions for a place to host the big file, please let me know.

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Sorry. Apparently it was a few bytes larger than allowed. I'll go back to the drawing board to see if there is anything else I can do to shrink this file without totally destroying the imagery.

[nprev]

Tom, can you link it to an external site? That would work. (MOST anxious to see this; it sounds great!!!)

[CosmicRocker]

Nick: I tried Flickr and Picasa Web Albums without success. That's why I was asking if anyone knew of another site that accepted this kind of file. A few years ago I made one of these of Itokawa and a certain friend of umsf hosted it. Since Vesta is roughly spherical, it does not appear quite as exciting in 3D as Itokawa did, but it is still nice to see it in stereo.