Asteroids are known to possess dusty regolith on their surfaces and scientists have always assumed that the material - composed of grains of rock under a centimeter in size - is formed through asteroid and micrometeorite impact debris settling onto the asteroids.
But there's a problem with this model.
PHOTOS: Psychedelic Landscapes of Asteroid Vesta
Over asteroid evolution timescales, there is too much regolith on small asteroids' surfaces to have been deposited there solely through impacts. The impact energies of these collisions, the asteroid spin rate and the very low gravity asteroids possess means the debris should be flung away into interplanetary space.
So how did all that regolith get there?
While carrying out tests on meteorites found on Earth, the researchers modeled the space environment to see how these samples deteriorated.
"We took meteorites as the best analog of asteroid surface materials that we have on the Earth," said Marco Delbo of the Observatoire de la Côte d'Azur, France. "We then submitted these meteorites to temperature cycles similar to those that rocks experience on the surfaces of near-Earth asteroids and we found that microcracks grow inside these meteorites quickly enough to entirely break them on timescales much shorter than the typical lifetime of asteroids."