Albedo Observation by Hayabusa2 LIDAR: Instrument Performance and Error Evaluation

作者:Yamada Ryuhei*; Senshu Hiroki; Namiki Noriyuki; Mizuno Takahide; Abe Shinsuke; Yoshida Fumi; Noda Hirotomo; Hirata Naru; Oshigami Shoko; Araki Hiroshi; Ishihara Yoshiaki; Matsumoto Koji
来源:Space Science Reviews, 2017, 208(1-4): 49-64.
DOI:10.1007/s11214-016-0240-9

摘要

The Japanese asteroid explorer Hayabusa2 was launched at the end of 2014. Hayabusa2 is supposed to observe the near-Earth C-type asteroid 162173 Ryugu (1999 JU3) and bring surface material samples back to Earth in 2020. It is equipped with Light Detection and Ranging (LIDAR) instrument for laser ranging which can be used to measure the intensities of transmitted and received pulses. The intensity data can be used to estimate the normal albedo of Ryugu at a laser wavelength of 1.064 mu m. To perform this estimation, we determined the transfer functions of the laser module and receiver to convert the intensity data into pulse energies, along with the utilization ratio of the returned pulse energy, through verification tests of the LIDAR flight model. Then, we evaluated the error of the normal albedo. This error is affected not only by the performance of the LIDAR but also by the slope and roughness of the asteroid's surface. In this paper, we focus on the error in the normal albedo due only to the instrument error, which will be 18.0 % in an observation at a nominal altitude of 20 km.