Re: Was the astreoid belt formed from a object orbiting too close to Mars?

That's actually an interesting idea, but it does not seem likely for a couple of reasons.

First, it is hard to imagine how Mars got a moon of that size (if you pushed all the asteroids together, you'd have a planet about 1000 km in radius). If you look at the rocky, Terrestrial worlds, you see that only Mars and the Earth have moons at all. Mars's moons are almost certainly captured asteroids, just from their appearences and compositions. Earth's Moon likely formed via a massive collision with a large body early in Earth's lifetime. Such an even would probably be rare (Earth is the only planet were this seems to have happened). Additionally, since the Moon formed from matter that was blasted into Earth orbit, its orbit is fairly circular. Thus, if Mars did have such a satellite, that satellite's orbit would probably also be circular, not highly elliptical.

Of course, this argument is just one of likihoods - it does not really prove that Mars could not have had such a satellite. However, if you calculate how close the satellite would need to pass in order to be ripped appart by tidal forces, you get about 1.4 times the radius of Mars for the weakest possible satellite (one that is just a pile of rubble held together by its own gravity). Since the radius of Mars is about 3400 km, this means that the satellite would hit Mars before being tidally torn apart.

These two thoughts make me think that it is very unlikely that such a senario could have played out. It is not impossible, as far as I can see. But in science, we seldom really prove anything is impossible, just unlikely. In this case, we have what we currently think (this, as is always the case in science, may change!) is a better idea for how to form asteroids. Namely, we think that they formed where they are now, and were never able to form a full planet due to Jupiter's graviational resonances. Resonances allow small tugs to add up to major effects over long time periods, and in this case, Jupiter was probably enough to break up the asteroids as they "tried" to form a planet.

A good resource on planets and satellites is William Hartmann's "Moons and Planets". Or, you might try The Nine Planets.