A Japanese spacecraft bombed an asteroid and it barely flinched

By Leah Crane

In 2019, Japan’s Hayabusa 2 spacecraft bombed the asteroid Ryugu, using explosives to shoot it with a 2.5-kilogram lump of copper to create an artificial crater. Scientists expected this impact to shake the ground, but its actual effect was far milder.

Hayabusa 2 images have shown that the surface of Ryugu has fewer small craters than we’d expect for an asteroid of its size, which probably indicates that dust is being moved somehow to fill in those craters. Asteroids do not have significant atmospheres, …