Hayabusa2's touchdown on Ryugu reveals its surface in stunning detail

High-resolution images and video were taken by the Japanese space agency's Hayabusa2 spacecraft as it briefly landed to collect samples from Ryugu - a nearby asteroid that orbits mostly between Earth and Mars - allowing researchers to get an up-close look at its rocky surface, according to a new report. During the touchdown Hayabusa2 obtained a sample of the asteroid, which it will bring back to Earth in December 2020. The detailed new observations of Ryugu's surface during the touchdown operations help scientists understand the age and geologic history of the asteroid, suggesting that its surface color variations are likely due to rapid solar heating during a previous temporary orbital excursion near the Sun. On February 21, 2019, after months of orbital observations to select the target location, the Hayabusa2 spacecraft descended to the surface of Ryugu to conduct its first sample collection, picking up surface material from the carbon-rich asteroid. Previous Hayabusa2 observations have shown that Ryugu's surface is composed of two different types of material, one slightly redder and the other slightly bluer. The cause of this color variation, however, remained unknown. During Hayabusa2's touchdown, onboard cameras captured high-resolution observations of the surface surrounding the landing site in exceptional detail - including the disturbances caused by the sampling operation. Tomokatsu Morota and colleagues used these images to investigate the geology and evolution of Ryugu's surface. Unexpectedly, Morota et al. observed that Hayabusa2's thrusters disturbed a coating of dark, fine-grained material that appeared to correspond with the surface's redder materials. By relating these findings with the stratigraphy of the asteroid's craters, the authors conclude that surface reddening was caused by a short period of intense solar heating, which could be explained if Ryugu's orbit took a temporary turn towards the Sun.

Credit: 
American Association for the Advancement of Science