橋本 樹明

The dynamical environment about and on Asteroid 25143 Itokawa is studied using the shape and rotation state model estimated during the close proximity phase of the Hayabusa mission to that asteroid. We first discuss the general gravitational properties of the shape model assuming a constant density. Next we discuss the actual dynamical environment about this body, both on the surface and in orbit, and consider the orbital dynamics of a Hayabusa-like spacecraft. Then we detail one of the approaches used to estimate the mass of the body, using optical and lidar imaging, during the close proximity phase.

The MUSES-C mission is the world first sample and return attempt to or from the near Earth asteroid. In deep space, it is hard to navigate, guide, and control a spacecraft on a real-time basis remotely from the earth mainly due to the communication delay. So autonomy is required for final approach and landing to an unknown body. It is important to navigate and guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper describes various kinds of robotics technologies applied for MUSES-C mission. An autonomous descent scheme and a novel visual navigation system are proposed and presented in detail. The validity and the effectiveness of the proposed methods are confirmed and evaluated by numerical simulations and flight results.

The Japanese asteroid exploration spacecraft Hayabusa autonomously performed touchdown two times in November 2005. The autonomous guidance and navigation capability is installed aboard the spacecraft. The GNC system collects the laser altimeter, laser range finders and navigation cameras information aboard and is designed to estimate where the spacecraft is and to decide the path correction maneuvers. The programmed function includes the image processing designed to detect an artificial target marker location to approach and cancel the relative velocity. A terrain alignment maneuver is also accomplished by both altitude and attitude control. This paper presents how autonomous guidance and navigation was performed in Hayabusa mission.

The MUSES-C mission is the world's first sample and return attempt to/from the near Earth asteroid. In deep space, it is hard to navigate, guide, and control a spacecraft on a real-time basis remotely from the earth mainly due to the communication delay. So autonomy is required for final approach and landing on an unknown body. It is important to navigate and guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper describes various kinds of robotics technologies applied for MUSES-C mission. A global mapping method, an autonomous descent scheme, and a novel sample-collection method, and asteroid exploration robot are proposed and presented in detail. The validity and the effectiveness of the proposed methods are confirmed and evaluated by numerical simulations and some experiments.

Following the LUNAR-A and SELENE, Japan has studied the moon lander with the reliable and safe landing capability by autonomous obstacle avoidance. The primary mission was set as the moon science around a central peak of a large crater to reveal the moon origin and evolution. For this concept, night survival capability is considered as optional, due to the required hard technology. However, night survival and long stay capability are essential for the genuine and full-scale moon development in the future. Even for the scientific exploration, a few months or a year mission period is requested from the scientists. For lunar base and moon utilization, a few years or unlimited system life period will be required. There are many proposals for this night survival capability, such as RTG utilization, location at the permanent sunshine zone, heat insulation tent by MLI, and so on. As the first step of the night survival capability study, the effect and damage of the moon night coldness is tested by thermal vacuum facility. Also some proposed concepts, including the wide utilization of moon regolith, are evaluated by thermal analysis for the moon base in the future.

We are developing a whale ecology observation satellite system, comprised of a small satellite (WEOS), a ground operation center and probes attached to whales in the ocean. The NASDA (JAXA at present) has successfully launched the small satellite on 14th December, 2002 as one of the piggyback payloads of H-IIA-4 rocket from Tanegashima Space Center. The orbit of the WEOS is sun synchronous with the height of 800 km, and the attitude is stabilized by gravity gradient torque caused by a deployable mast of 3 m long. The satellite is manufactured by using industrial parts through careful environmental tests. Performance of the WEOS on the orbit is perfect, and its antennas for communications are kept facing to the earth. Operations for attaching the probes to whales are going on. The probes send ecological data to the WEOS, in which position data from a GPS receiver onboard the probes are included. The WEOS has a space GPS receiver on board, and the position data on the orbit are sent by telemetry to the ground station together with the Doppler shift data obtained by a PLL receiver of the satellite. We can thus locate the probe on the ocean by inversion analysis, which contributes as an auxiliary tool for studying migration of whales. Based on the experience of this mission, we are proposing a formation flight of 8 to 10 of such small satellites uniformly spaced on two polar orbital planes, which allows a cost effective realization of an advanced multi purpose satellite system. This paper describes the outline of the WEOS system, and the future prospect realized by the formation flight of similar satellites on the earth.

本報告書では,宇宙科学研究所のX線天文観測科学衛星「あすか」および「ASTRO-E」の姿勢(および軌道)制御系について詳述する。これら二つの科学衛星は,その規模(重量,寸法,有能電力等)に於いてかなり異なるにもかかわらず,両者の姿勢制御系は宇宙科学研究所の天文観測衛星のために開発された,独特の多くの特徴を共有している。本報告では,1)ミッション要求を満たすための姿勢(軌道)制御系の機能構成および設計方針,2)姿勢(軌道)制御系機器の構成と性能の概要,3)各制御機能の動作原理(制御則),4)制御系動作実証試験,および5)「あすか」の姿勢制御系に対する軌道上動作・性能の評価,について報告する。本報告書を纏めるに当たり,筆者等は,本報告書が人工衛星,特に天文観測科学衛星の開発や運用に携わるエンジニアにとって,実際を知るための興味深く有用なテキストとなることを願うものである。

「はやぶさ」は2003年5月9日に打ち上げられた小惑星探査ミッションで、Ｓ型小惑星1998SF36をそのターゲット天体としている。現在ミッションは打ち上げ後の初期運用フェーズを終え、定常運用へと移行している。 このミッションは工学ミッションとして（１）電気推進の運用：（２）自律航法；（３）微小低重力下でのサンプリング；（４）カプセルの再突入と回収、の4つの大きな課題を担っている。 サイエンス観測としては、本講演で延べるAMICA（Asteroid Multiband Imaging CAmera）の他に赤外分光計、蛍光Ｘ線スペクトロメータ、LIDARが理学観測に用いられることになっている。 AMICAは光学航法カメラ（Optical Navigation Camera: ONC）の望遠カメラ（ONC-T）にフィルタと偏光子を装着したもので、衛星システム上では望遠光学航法カメラ（ONC-T）を理学観測機器として捉えるときに限り、特にAMICAというシステム呼称が用いられている。 このカメラは8バンドのフィルタホイールを搭載しているが、1バンドを航法用のwideバンドフィルタに用いるため分光フィルタは7バンドを装備している。これらは小惑星の分光観測システムであるECAS（EightColor Asteroid Survey）で使用されるフィルタセットに準拠させている。また偏光子は視野の一部を占めるよう、CCDの直上に配置している。これは光学ガラスに一定の方向に整列した細長い銀粒子を埋めこんだもので、これをCCD面の１辺に４方向の偏光面角（0、 45、 90、 135度）を持つように切り出した小片を配置したものである。 本講演では、これら総合試験・性能評価で最終的に得られた結果、また初期運用で得られたデータの紹介など、AMICAの現況と今後実施する小惑星観測について紹介する。

The MUSES-C mission is the world's first sample and return attempt from the near Earth asteroid. In deep space, it is hard to navigate and guide a spacecraft on a real-time basis remotely from the earth mainly due to the communication delay. So autonomy is required for final approach and landing to an unknown body. It is important to guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper describes image processing methods applied for MUSES-C mission. A global mapping method and an image based descent scheme are proposed and presented in detail. The effectiveness of the proposed methods is confirmed by graphical simulations.

This paper describes a GNC (Guidance Navigation and Control) in MUSES-C asteroid sample return mission. In deep space, it is difficult to navigate, guide, and control a spacecraft on a realtime basis remotely from the earth mainly due to the communication delay. So autonomous navigation and guidance is required for the final approach and landing to an asteroid. It is important to navigate and guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper describes the CNC method based on optical sensors. The validity of the proposed method has been confirmed by computer simulations.

This paper presents accurate onboard navigation system for Lunar landers or orbiters, based on the crater identification. The navigation system consists of three stages. At first, craters are extracted from the surface images taken onboard, and the list of positions and radii of detected craters is obtained. The second step is identification between detected craters and known terrain maps obtained by other missions in advance, The final stage is the calculation of position towards Moon-fixed coordinates. To verify the effectiveness and performance of the proposed navigation system, computer simulations including image processing are performed.

Global mapping from the sun side and the terminator side are scheduled in MUSES-C mission. The spacecraft keeps the home position around the asteroid during global mapping. This paper proposes a method for a spacecraft to keep the home position autonomously. The spacecraft is navigated based on the image obtained by ONC and the range information obtained by LIDAR. This paper also proposes a global mapping method to estimate the shape of the asteroid based on motion stereo techniques.

This paper proposes a direct geographic recognition scheme from a gray-scale image without shape reconstruction. Several geographic categories are expressed in 3 x 3-arrays of normal-vector directions. Only by looking up a table, observed pixel-values (intensities) in a window are transformed into indices of conformity whether the scene in the window is due to each geographic category or not. Geographical features are extracted by multi-resolution interpretation and fuzzy-logical operations. The feasibility and robustness of the proposed method is shown by some computer simulations.

This paper presents an autonomous descent and touch-down scheme of the asteroid sample and return spacecraft, MUSES-C. The spacecraft uses some optical sensors. such as a navigation camera (ONC-W1). a laser altimeter (LIDAR), a short range laser sensor (LRF), and an artificial landmark (TM) which is released at about 100m altitude. Navigation system contains image processing, integration of visual and range information, and Kalman filtering. To realize "time of arrival" guidance, the descending plan is uploaded to the spacecraft, considering the asteroid motion. Six degree-of-freedom control is performed by RCS and reaction wheels (RW). In this paper, after brief explanation of MUSES-C navigation, guidance, and control (NGC) system and descent and touch-down scenario, the navigation scheme mainly focused on image processing, descent guidance scheme, and six degree-of-freedom thruster control are described. To verify the performance of the proposed scheme, computer simulations including Graphical Asteroid Simulator are performed.

In recent years, many researchers have earnestly studied and developed walking robots. Walking robots have so high mobility that they can move on rough terrain, climb steps, and cross ditches. In the field of planetary exploration, robots with multiple legs are expected to explore inside craters etc. However, so far developed walking robots are too big and heavy to explore the lunar or planetary surface. So this paper proposes a novel design scheme for multi-legged robots. To show the effectiveness of the proposed scheme, the design analysis on static and dynamic motion is performed.

This paper describes a descent navigation and guidance in MUSES-C sample return mission. In deep space, it is difficult to navigate, guide, and control a spacecraft on a real-time basis remotely from the earth mainly due to the communication delay. So autonomous navigation and guidance is required for final approach and landing to an unknown body. It is important to navigate and guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper proposes a GNC method based on optical sensors. The validity of the proposed method is confirmed by computer simulations.

This paper proposes a direct geographic recognition scheme from a gray-scale image without shape reconstruction. Several geographic categories are expressed in 3x3-arrays of normal-vector directions. Only by looking up stable, observed pixel-values (intensities) in a window are transformed into indeces of conformity whether the scene in the window is due to each geographic category or not. The recognition is accomplished by multi-resolution interpretation and fuzzy-logical operations. The results of recognition-has shown the feasibility and robustness of the proposed method. (C) 1999 Elsevier Science Ltd. All rights reserved.

An impending demand for exploring the small bodies such as the comets and the asteroids envisioned the Japanese MUSES-C mission to the near Earth asteroid Nereus, An autonomous optical guidance and navigation strategy around the asteroid is discussed in this paper. Four major new schemes are dealt with hers: They are (1) Aligned intercept guidance, (2) Strategic building of the flight phases, (3) Image processing of line-of-sight shift information instead of characteristic point tracking, and (4) Stability and accuracy analysis associated with the guidance and navigation strategies developed here. Some comprehensive numerical illustrations are also given to support them. 1999 Elsevier Science Ltd. All rights reserved.

本報告書は, 宇宙科学研究所のこれまでおよび近い将来の天文観測用科学衛星の姿勢決定系に採用されてきたカルマンフィルタに関して, そのアルゴリズムおよび実用上の工夫を中心に記述する。宇宙科学研究所の天文観測用科学衛星で, 姿勢決定にカルマンフィルタがはじめて適用されたひ"ぎんが"の打ち上げ(1987年2月)から10年以上が経過した。この間に打ち上げられた天文観測衛星の飛翔ごとに, その経験にもとづいてカルマンフィルタにおいても実用上の工夫が取り入れられてきた。一方, 観測ミッションの達成に必要な姿勢制御精度/姿勢決定精度はますます厳しくなり, カルマンフィルタを用いる場合にも, より厳密なアルゴリズムを適用することが必要となってきた。以上の背景を基に, 本報告書では, これまで用いてきたカルマンフィルタの設計や適用の方法をまとめておくことを通じて, 今後の衛星への確実な技術継承を図ることを目的としている。本報告書の構成は, 以下の通りである。第1章では, 宇宙科学研究所の天文観測用科学衛星における姿勢決定系の開発の流れを示す。第2章では, 姿勢決定系におけるカルマンフィルタのアルゴリズムを, 付録 A に示した一般的定式化を基に記述する。第3章では, カルマンフィルタの性能を定めるパラメータと性能との関係を明らかにし, カルマンフィルタの設計指針を与える。第4章では, これまでの天文観測用科学衛星におけるカルマンフィルタの適用方法を, 実際の衛星を対象として具体的に説明する。付録 A には, カルマンフィルタの一般的定式化をまとめて記載しておく。なお, 付録 B 以下では, 姿勢決定系カルマンフィルタの定式化を図る上で不可欠であるオイラーパラメータ, それに基づく姿勢運動の方程式の記述, カルマンフィルタの状態変数を決定する上で必要となる可観測性の検証方法についてまとめておく。

This paper describes an autonomous landing system for MUSES-C sample return mission. In deep space, it is difficult to navigate, guide, and control a spacecraft on a real-time basis remotely from the earth mainly due to the communication delay. So autonomous navigation and guidance is required for final approach and landing to atl unknown body. It is important to navigate and Guide a spacecraft to the landing point without hitting rocks or big stones. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. This paper proposes an autonomous landing method based on optical sensors. The validity of the proposed method is confirmed by graphical simulations. This paper also proposes a sample collector method to collect the surface materials.

本報告書は, 宇宙科学研究所のこれまでおよび近い将来の天文観測用科学衛星の姿勢決定系に採用されてきたカルマンフィルタに関して, そのアルゴリズムおよび実用上の工夫を中心に記述する。宇宙科学研究所の天文観測用科学衛星で, 姿勢決定にカルマンフィルタがはじめて適用されたひ"ぎんが"の打ち上げ(1987年2月)から10年以上が経過した。この間に打ち上げられた天文観測衛星の飛翔ごとに, その経験にもとづいてカルマンフィルタにおいても実用上の工夫が取り入れられてきた。一方, 観測ミッションの達成に必要な姿勢制御精度/姿勢決定精度はますます厳しくなり, カルマンフィルタを用いる場合にも, より厳密なアルゴリズムを適用することが必要となってきた。以上の背景を基に, 本報告書では, これまで用いてきたカルマンフィルタの設計や適用の方法をまとめておくことを通じて, 今後の衛星への確実な技術継承を図ることを目的としている。本報告書の構成は, 以下の通りである。第1章では, 宇宙科学研究所の天文観測用科学衛星における姿勢決定系の開発の流れを示す。第2章では, 姿勢決定系におけるカルマンフィルタのアルゴリズムを, 付録 A に示した一般的定式化を基に記述する。第3章では, カルマンフィルタの性能を定めるパラメータと性能との関係を明らかにし, カルマンフィルタの設計指針を与える。第4章では, これまでの天文観測用科学衛星におけるカルマンフィルタの適用方法を, 実際の衛星を対象として具体的に説明する。付録 A には, カルマンフィルタの一般的定式化をまとめて記載しておく。なお, 付録 B 以下では, 姿勢決定系カルマンフィルタの定式化を図る上で不可欠であるオイラーパラメータ, それに基づく姿勢運動の方程式の記述, カルマンフィルタの状態変数を決定する上で必要となる可観測性の検証方法についてまとめておく。