Millennium-Old Micrometeorite Swarm Scratched Ryugu's Surface

New analysis of Hayabusa2 samples shows Ryugu bears a nanometer-thick sodium layer on its surface, evidence of recent micrometeorite bombardment as the asteroid moved through a dense meteoroid swarm about 1,000 years ago; researchers also found glassy impact features and solar-wind–related iron changes, with findings published in The Astrophysical Journal Letters.