Derivation of 1.064 μm albedo on the C-type asteroid Ryugu from laser pulse intensity measurement of the Hayabusa2 LIDAR

Abstract Japanese asteroid explorer Hayabusa2 arrived at C-type asteroid 162173 Ryugu in June 2018. Laser altimeter (LIDAR) onboard Hayabusa2 measured its own transmitted laser pulse intensity and returned pulse intensity from the surface of Ryugu until November 2019. Because the Ryugu surface is extremely rough, topography dominates material property in the conventional derivation of normal albedo. We develop a method to derive the albedo from the rough surface of the C-type asteroid at the LIDAR laser wavelength of 1.064 μm. Using the intensity data obtained before the conjunction of the spacecraft with the Sun, the albedo map covering an equatorial band between – 40˚ and + 20˚ in the latitude is created with 2˚ by 2˚ resolution. The average of the albedo is 0.0406 [[EQUATION]] 0.0031, while about half of them are in the range between 0.04 and 0.045. The low and uniform albedo feature is common to other remote-sensing observations of Ryugu by visible and near-infrared cameras onboard the Hayabusa2.