The deficit of small craters on the asteroid 433 Eros, 2867 steins and 25143 Itokawa can be caused by seismic tremors as a result of meteoritic bombardment, according to U.S. scientists. An article about the simulation process, accepted for publication in Icarus.
Among half a dozen asteroids to date have investigated the spacecraft, three bodies are deficit of small craters and a large number of craters destroyed. This asteroid 433 Eros, 2867 steins and 25143 Itokawa. The largest of them — the near-earth asteroid Eros, its average diameter is about 17 kilometers. The main-belt asteroid steins has an average diameter of about five miles, and near-earth asteroid Itokawa — only 350 metres away.
American scientists James E. Richardson (James E. Richardson), Jordan K. Stekloff (K. Jordan Steckloff) and David A. Minton (David A. Minton) using computer simulations have reproduced the process of meteorite bombardment of the surfaces of these asteroids. The result of each collision formed a new crater was formed regolith — the loose surface layer, and also experienced seismic shaking of the asteroid, which was forced to move the regolith and thereby gradually destroying older craters. These simulations correctly reproduced the average thickness of the layer of regolith on the asteroid Eros (about 80 meters), the asteroid steins (about 155 meters, which is consistent with observations, which give an estimate of the thickness of the layer is approximately 145 metres) and Itokawa — about 5 meters.
Richardson and his colleagues believe that seismic shaking as a result of meteoritic bombardment are the cause of the destruction of small craters on the surface of asteroids, whose average diameter is less than 25 kilometers. In addition, the observable layer of regolith on asteroids such may be formed exclusively by percussion means, the thickness of the layer can be used as an additional parameter in determining the age of the surface of such bodies.
Near-earth asteroid Eros in 2000-2001 examined the spacecraft NEAR Shoemaker was the first ever soft landing on an asteroid. Snapshots of the asteroid steins were made by the spacecraft “Rosetta”. A near-earth asteroid Itokawa studied the mission of “Hayabusa-1”. We are told how the samples of regolith with Itokawa scientists found traces of collision with another body, and how this asteroid formed stones with rounded edges, reminiscent of a pebble.