I’ve read so much debunking of the idea that meteorites are rubble-piles, instead of solid rocks, that I am generally skeptical of theories that rely on the rubble-pile concept, like this so-called solution to the meteorite color mystery:
The Earth “changes the colour” of asteroids by shaking them up as they pass, according to scientists.
Researchers report that this solves the mystery of why the meteorites that land on the Earth often do not match the colour of asteroids in space.
Dr Clark Chapman, an astronomer from the Southwest Research Institute in Boulder, Colorado, in the US explained that these asteroids were “not monolithic, solid bodies”, and were more like “rubble piles”.
So on the surfaces of these rubble piles, rocks are shaken and turned over, to reveal a fresh, unweathered surface underneath.
I’m not sure asteroids must have a rubble pile structure to match the data - could it be that they’re solid bodies, but covered with loose debris and dust, as explained in Tom Van Flandern’s NEAR Challenge below, which he won?
The exploded planet hypothesis (as described in Dark Matter, Missing Planets and New Comets) implies that all asteroids and comets are formed as debris clouds during the explosion of planet or moon-sized bodies at astronomically recent epochs. Only those asteroids involved in collisions will have their orbiting debris removed, forming families (in the case of long-ago collisions) or jet streams (in the case of recent collisions). For most “loner” asteroids and comets, the original debris clouds around the primary nucleus should still be intact. The debris would consist of material of all sizes from dust to near-primary-nucleus size. Normal evolution of such debris clouds under tidal forces would tend to concentrate much of the debris into the orbital plane, and to collect some of that planar debris in an equatorial ring at the synchronous satellite orbit location (typically 1-2 radii above the asteroid surface). Debris inside the synchronous orbit should be cleared out by tidal forces and mostly found now lying on the surface of the primary asteroid.
Besides, I thought this rubble-pile idea was put to bed already - hasn’t every actual observation of both asteroids and comets turned up solid bodies, as below? Just sayin - I know the theory is that they’re rubble piles, but the observations actually support solid bodies at least as well:
Swift’s Take on Deep Impact http://www.universetoday.com/am/publish/swift_take_deep_impact.html?672005
Summary - (Jul 6, 2005) Scientists monitoring NASA’s Swift satellite had a good view of Deep Impact’s collision with Comet Tempel 1. … One of its most important observations from the impact is a quick rise in ultraviolet light. This means that the impactor struck a hard surface, as opposed to something soft and snowy.
…The Deep Impact team also mentioned “layers”, with the higher material rough and the lower portions of the surface smooth. This suggests a geologically evolved object rather than a primitive one.