Guidance, navigation, and control of Hayabusa2 touchdown operations

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https://doi.org/10.1007/s42064-020-0086-5

Guidance, navigation, and control of Hayabusa2 touchdown operations Fuyuto Terui1 (), Naoko Ogawa1 , Go Ono1 , Seiji Yasuda2 , Tetsuya Masuda2 , Kota Matsushima2 , Takanao Saiki1 , and Yuichi Tsuda1 1. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 252-5210, Japan 2. 3rd Space Technology Department, Space System Division, NEC Corporation, Tokyo 183-8501, Japan

ABSTRACT

KEYWORDS

Hayabusa2 is a Japanese sample return mission from the asteroid Ryugu. The Hayabusa2

small body exploration

spacecraft was launched on 3 December 2014 and arrived at Ryugu on 27 June 2018. It

touchdown

stayed there until December 2019 for in situ observation and soil sample collection, and

astrodynamics

will return to the Earth in November or December 2020. During the stay, the spacecraft

guidance

performed the first touchdown operation on 22 February 2019 and the second touchdown on

navigation

11 July 2019, which were both completed successfully. Because the surface of Ryugu is rough

control

and covered with boulders, it was not easy to find target areas for touchdown. There were several technical challenges to overcome, including demanding guidance, navigation, and

Research Article

control accuracy, to realize the touchdown operation. In this paper, strategies and technical

Received: 17 February 2020

details of the guidance, navigation, and control systems are presented. The flight results

Accepted: 15 May 2020

prove that the performance of the systems was satisfactory and largely contributed to the

© Tsinghua University Press

success of the operation.

1

Table 1

Introduction

Hayabusa2 is a Japanese sample return mission from the asteroid Ryugu [1, 2]. The Hayabusa2 spacecraft was launched on 3 December 2014 and arrived at Ryugu on 27 June 2018 [3]. It stayed there until November 2019 for in situ observation and soil sample collection; it is now flying back to the Earth and will return in November or December 2020. During the stay, the spacecraft performed several descent operations, as shown in Table 1 [4–11], such as deploying rovers, dropping SCI to form an artificial crater, and touchdown. The first touchdown operation was performed successfully on 22 February 2019 [9, 10], and the spacecraft successfully touched down on Ryugu for the second time on 11 July 2019 [11]. The locations for the first and second touchdowns are shown with nicknames in Fig. 1. The strategy adopted for touchdown (TD) was a technique called pinpoint touchdown (PPTD), in which the spacecraft performs GNC with respect to a small, reflective, beanbag-like target marker (TM) that had



2020

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Operation ID

List of descent operations Date

Objectives

MID

1–2 Aug. 2018

Asteroid global observation

GRV

6–7 Aug. 2018

Asteroid gravity estimation

TD1-R1

11–12 Sept. 2018 Touchdown rehearsal

MNRV

20–21 Sept. 2018 MINERVA-II release

MSCT

2–4 Oct. 2018

MASCOT release

TD1-R1-A

14–15 Oct. 2018

Touchdown rehearsal

TD1-R3

24–25 Oct. 201