Hayabusa2/NIRS3 spectral observations of asteroid (162173) Ryugu
Résumé
On 27 June 2018, JAXA's Hayabusa2 spacecraft arrived at a distance of 20 km from its target 162173 Ryugu, a sub-km sized asteroid in the near-Earth space, and began its 1.5-year asteroid proximity operation. We have performed near-infrared (1.8-3.2 µm) spectroscopic observations of Ryugu using the NIRS3 instrument onboard Hayabusa2 to begin characterizing and mapping the surface composition. The initial data, obtained by NIRS3 at a spatial resolution of about 35 m, show a very dark surface with little spectral variations across the surface. At this stage, the lack of a significant 2.7-µm feature illustrates that the spectra of Ryugu are different from those of phyllosilicate-rich carbonaceous chondrites. We will present the results of the analysis of the NIRS3 data, including the high-resolution data to be obtained during the first descent operations.