Alignment determination of the Hayabusa2 laser altimeter (LIDAR)

Hirotomo Noda,Naoyuki Hirata,Yuichiro Cho,Seiji Sugita,Arika Higuchi,Makoto Shizugami,Takanao Saiki,Hiroki Senshu,Naoko Ogawa,Chikatoshi Honda,Yasuhiro Yokota,Fumi Yoshida,Sho Sasaki,Kazuyoshi Asari,Masahiko Hayakawa,Naoya Sakatani,Manabu Yamada,Yuto Takei,Seiitsu Tsuruta,Keiko Yamamoto,Hiroshi Araki,Atsushi Fujii,Ryuhei Yamada,T Kouyama ,Go Ono,Tomohiro Yamaguchi,Koji Matsumoto,Shozo Nakazawa ,Naru Hirata,Rie Honda,Hirotaka Sawada,Shoko Oshigami,Tomokatsu Morota,Makoto Yoshikawa,Eri Tatsumi,Hidehiko Suzuki,Satoshi Tanaka,Shota Kikuchi,Shinsuke Abe,T Takahashi ,Noriyuki Namiki,S Watanabe ,Moe Matsuoka,Yuichi Tsuda,Fuyuto Terui,Shingo Kameda,Takahide Mizuno,Kazunori Ogawa,Yuya Mimasu,Yoshiaki Ishihara,Kunihiko Yoshikawa ,Kazuo Yoshioka

doi:10.1186/s40623-020-01342-8

Abstract

In this study, we determined the alignment of the laser altimeter aboard Hayabusa2 with respect to the spacecraft using in-flight data. Since the laser altimeter data were used to estimate the trajectory of the Hayabusa2 spacecraft, the pointing direction of the altimeter needed to be accurately determined. The boresight direction of the receiving telescope was estimated by comparing elevations of the laser altimeter data and camera images, and was confirmed by identifying prominent terrains of other datasets. The estimated boresight direction obtained by the laser link experiment in the winter of 2015, during the Earth’s gravity assist operation period, differed from the direction estimated in this study, which fell on another part of the candidate direction; this was not selected in a previous study. Assuming that the uncertainty of alignment determination of the laser altimeter boresight was 4.6 pixels in the camera image, the trajectory error of the spacecraft in the cross- and/or along-track directions was determined to be 0.4, 2.1, or 8.6 m for altitudes of 1, 5, or 20 km, respectively.

Highlights

Precise determination of the alignment of a laser altimeter with respect to spacecraft is indispensable for the accurate estimation of the footprint positions on the surface of a celestial body for lunar and planetary missions
The second is to adjust the spacecraft positions such that topographic features contained in tracks of the laser altimeter (called Light Detection and Ranging (LIDAR) for the Hayabusa2 mission) fit to the global shape model that exists at the time of estimation (Matsumoto et al 2020)
When we use many elevation maps, the candidate pixel position of the Light detection and ranging (LIDAR) field of view may be narrowed as the topography differs by map

Summary

Introduction

Precise determination of the alignment of a laser altimeter with respect to spacecraft is indispensable for the accurate estimation of the footprint positions on the surface of a celestial body for lunar and planetary missions. In the case of Hayabusa, the initial trajectory determined from range and range-rate measurements by radio-tracking from the Usuda Deep Space Center on Earth of the Japan Aerospace Exploration Agency (JAXA) may contain an error in the order of hundreds of meters This is because scientific observations are normally carried out when the spacecraft is not visible from the Earth. The second is to adjust the spacecraft positions such that topographic features contained in tracks of the laser altimeter (called Light Detection and Ranging (LIDAR) for the Hayabusa mission) fit to the global shape model that exists at the time of estimation (Matsumoto et al 2020) The latter is useful for longer-period orbit determination, because typically the cadence of image acquisition is relatively low due to the data downlink budget. The accuracy of trajectory is dependent on the accuracy of the alignment determination of the altimeter with respect to the spacecraft

Methods

Results

Discussion

Conclusion