Samples recovered from the nearby carbonaceous asteroid Ryugu by the Hayabusa2 spacecraft are representative of both the asteroid’s surface and sub-surface, according to a new report. 

From June 2018 to November 2019, Hayabusa2 investigated Ryugu, characterizing the asteroid from orbit, and collecting samples of the rocky surface for return to Earth. Two landing operations were performed: one which sampled the material on Ryugu’s surface, and another that collected sub-surface material excavated by an artificial impact experiment. In December 2020, Hayabusa2 delivered roughly five grams of material to Earth. Here, Shogo Tachibana and colleagues describe the second sample collection and the physical characteristics of the returned samples. 

Using images and videos captured during both landing operations, Tachibana et al. characterized the properties of the pebble-sized rocks scattered across Ryugu’s surface, showing they have similar morphologies to the asteroid’s larger boulders, with shapes ranging from quasi-spherical to flattened. Comparing these observations with the materials delivered to Earth, the authors show that the colors, shapes and structures of the samples are consistent with material surrounding each collection site on Ryugu. The findings indicate that the samples recovered during the Hayabusa2 mission are representative of Ryugu’s surface and subsurface material.  

For reporters interested in trends, Hayabusa2’s first sample collection effort was detailed by Tomokatsu Morota et al. in a May 2020 study in Science.