Thread: Why does the surface of Vesta look like it does?

Can anyone explain what we are seeing on the surface of Vesta? For a picture, got to Asteroid - Wikipedia, the free encyclopedia

I think a better picture is at the Vesta wiki, no?

4 Vesta - Wikipedia, the free encyclopedia

I would offer two theories.

It's a low impact collision object. Hit with enough impact to penetrate to that depth but not explode. More of an acretion merger than an impact due to the low average relative velocities of the asteroids and the low gravity of the objects..

Or

It's the core of the asteroid exposed by a previous impact that either exploded and blew off a lot of losely packed surface covering the more firmly packed core it or changed the rotation speed and increased the equatorial bulge drawing loose material off the poles towards the equator uncovering a more firmly packed core.

I think a better picture is at the Vesta wiki, no?

Oh yes. That gives us even more to try to explain.

Well, let us examine the features in detail. We have the general lumpiness, which is not unexpected in a relatively small body whose gravity is weak. We have a lot of craters too. But we also have a lot of features that are not craters, but gouges or wrinkles that haven an elongated character. What are they? We also have several "walls" that look like they could be parts of craters, but do not form complete craters. What is especially interesting is those rather elongated troughs that seem to extend from craters and somehow be part of whatever phenomenon formed the crater(s) from which extending, yet also have smaller craters and other features within them. If craters are formed by the impact of debris, what explains these elongated features? There are also linear rows of craters run together, forming stippled troughs. It would appear that such troughs are not fundamentally different from other linear features, nor from at least one very elongaged crater that exhibits a rebound peak in the middle of it, which is odd, because rebound peaks are normally thought to have resulted from being struck by an object, but the long oval shape does not seem consistant with that. Also, looking over the astroid generally, craters do not seem to be distributed at random, have a tendency to occur in rows. Regarding the linear troughs or crater rows or whatever: they often form sort of a crosshatched pattern, lying at approximately right angles. Why? I might also point out that the types of features seen are not unlike many found on Mars and other bodies, despite the fact that some of these bodies are much larger and would appear to lie in different orbital circumstances. On the whole, what I am seeing does not seem to be consistant with the idea that the surface was shaped simply by stuff colliding.

We know there are a number of variable forces at operation through time on these things. Acretion, collision, gravitational and static electric adhesion, gravitational tidal kneeding, rotational centrifugal shaping. What specific set of variables acting in what pattern resulted in some particular structure can't be known as we don't know enough about the relative probabilities of the forces to act in a particular pattern on the asteroids. We can understand the possibilities the variables can produce results but even a frequent pattern such as the "snowman" features, possibly produced by objects broken up by gravitational tidal forces before impact, can't be know at present to be probably produced by that condition or by a more random statistical varation of impact probabilities. We just don't know enough about the occurence and result of all the possible actors on the asteroids.

Not to say we don't know a lot about the possible actors on the object but to say that we don't know enough about the probability distribution yet to conclude that any particular set of acting patterns is more probable than others.

We have one observed planetary impact on record and it was of the tidal break up before impact type. We know there are is a posibility that possibly some bodies are lose enough to be fragmented like this to produce more impacts of this type. But the relative occurance of that type of body and impact to single body impact is unknown.

We could theorize on the assumtion that most "snowman" features are fragmented object impacts and conclude that some proportion of bodies are fragmentable in this way. For any variable in the possible forces we can assume some particular distribution (frequently such assuptions are supported some known facts) and conclude a variety of theoretical probabilitiy distributions for particular features.

If you were floating around in this neighborhood for 4 billion years or so, you would look a little beat up too. Sucker punched !! It didn't see it coming. LOL