船瀬 龍

A fuel-free attitude control system for a spinning solar sail which utilizes solar radiation pressure was developed. This system consists of thin-film devices attached to the sail that electrically control their optical parameters such as reflectivity, and the attitude control torque is generated by switching their optical parameters synchronizing with spin motion. Attitude control torque model for a sail of arbitrary shape and deformation was derived. The control system was implemented for Japanese interplanetary solar sail demonstration spacecraft IKAROS and the on-orbit attitude control performance was evaluated.

This paper describes an attitude determination strategy for spinner spacecraft based on the Sun and the Earth angles. This method realizes a complete spin vector determination using only one sun sensor. Thus this method is suitable for low cost, resource-limited spacecraft with a moderate attitude determination accuracy requirement. The method has been developed for and is actually used in IKAROS, which is a Japanese interplanetary solar sail demonstration mission. This paper introduces theoretical backgrounds of Sun-Earth based attitude determination and shows how the actual implementation was done in the IKAROS mission. Then the attitude determination performance achieved during the actual operation is evaluated.

This paper describes a modeling of attitude dynamics of spinning solar sail spacecraft under influence of solar radiation pressure (SRP). This method is verified and actually exploited in the attitude and trajectory guidance operation of Japanese interplanetary solar sail demonstration spacecraft IKAROS. IKAROS shows a unique attitude behavior due to strong SRP effect. This paper introduces a new generalized dynamics model called Generalized Spinning Sail Model (GSSM), which clearly explains physics behind the observed phenomena with only three parameters. Precise understanding of attitude dynamics through the GSSM led to 6 months of world first interplanetary trajectory guidance of solar sail-craft toward Venus. The GSSM also contributed to realize a zero-fuel spin axis maintenance for most of the flight path before the Venus flyby. In this paper, an overview of IKAROS attitude and trajectory control operation in the cruising phase, derivation of the proposed model and its implementation to the actual IKAROS operation are shown.

エンセラダスの南極付近から噴出するプリュームの発見は,氷衛星の内部海の海水や海中の揮発性成分や固体成分の直接サンプリングの可能性を示した大きなブレイクスルーであるといえる.これまでカッシーニ探査によって,プリューム物質は岩石成分と相互作用する液体の内部海に由来していることが明らかになったが,サンプリング時の相対速度が大きいこと,質量分析装置の分解能が低いことなどの問題があり,内部海の化学組成や温度条件,海の存続時間など,生命存在の可能性を制約できる情報は乏しい.本論文では,エンセラダス・プリューム物質の高精度その場質量分析とサンプルリターンによる詳細な物質分析を行うことで,内部海の化学組成の解明,初期太陽系物質進化の制約,そして生命存在可能性を探ることを目的とする探査計画を提案する.本提案は,"宇宙に生命は存在するのか"という根源的な問いに対して,理・工学の様々な分野での次世代を担う若手研究者が惑星探査に参入し結集する点が画期的であり,我が国の科学・技術界全体に対しても極めて大きな波及効果をもつ.

原始太陽系円盤を構成していた初期物質を探るためには,惑星形成時の熱変成の影響を免れた小惑星・彗星・惑星間塵といった小天体の研究が不可欠である.なかでも木星のラグランジュ点付近に存在するトロヤ群小惑星は,小惑星と彗星の間をつなぐ天体であり,原始太陽系円盤の物質分布や微惑星の成長・移動プロセスを調べる上で重要なターゲットである.本稿では,日本が世界に先駆けて実証したソーラー電力セイル技術を用いたトロヤ群小惑星探査ミッションを提案する.この探査は(1)トロヤ群小惑星の詳細な物質組成や熱史・衝突史を調べることで,その起源と進化を明らかにする, (2)惑星間塵の空間分布を測定することで,彗星・小惑星からの生成率や軌道進化に関する理解を深め,その結果を他の惑星系に応用する, (3)惑星間塵の影響の少ない小惑星帯以遠からの宇宙赤外線背景放射観測によって,宇宙初期に形成された第一世代の星を調べる,という科学目標をあわせ持つ,惑星科学・天文学・宇宙工学の融合ミッションである.

This paper introduces a new attitude control system for a solar sail, which leverages solar radiation pressure. This novel system achieves completely fuel-free and oscillation-free attitude control of a flexible spinning solar sail. This system consists of thin-film-type devices that electrically control their optical parameters such as reflectivity to generate an imbalance in the solar radiation pressure applied to the edge of the sail. By using these devices, minute and continuous control torque can be applied to the sail to realize very stable and fuel-free attitude control of the large and flexible membrane. The control system was implemented as an optional attitude control system for small solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). In-orbit attitude control experiments were conducted, and the performance of the controller was successfully verified in comparison with the ground-based analytical performance estimation. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

The orbit of a solar sail can be controlled by changing the attitude of the spacecraft. In this study, we consider the spinning solar power sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), which is managed by Japan Aerospace Exploration Agency (JAXA). The IKAROS attitude, i.e.; the direction of its spin-axis, is nominally controlled by the rhumb-line control method. By utilizing the solar radiation torque, however, we are able to change the direction of the spin-axis by only controlling its spin rate. With this spin rate control, we can also control indirectly the solar sail's trajectory. The main objective of this study is to construct the orbit control strategy of the solar sail via the spin-rate control method. We evaluate this strategy in terms of its propellant consumption compared to the rhumb-line control method. Finally, we present the actual flight attitude data of IKAROS and the change of its trajectory. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

JAXA launched the world's first deep space solar sail demonstration spacecraft "IKAROS" on May 21, 2010. IKAROS was injected to an Earth-Venus trajectory to demonstrate several key technologies for solar sail utilizing the deep space flight environment. IKAROS succeeded in deploying a 20 m-span solar sail on June 9, and is now flying towards the Venus with the assist of solar photon acceleration. This paper describes the mission design, system design, solar sail deployment operation and current flight status of IKAROS. © 2011 Elsevier Ltd. All rights reserved.

It is becoming imperative to have visual capabilities for space activities. There are increasing opportunities to use visual Images coupled with image processing technologies for spacecraft sensing and control. To fill this need, we have developed a small, low-cost, high-performance image acquisition and processing unit (HP-IMAP), which uses commercial off-the-shelf technologies. In 2010, the HP-IMAP was launched to monitor a deployable structure. Herein, we describe the BP-IMAP and discuss Its qualification tests.

This paper describes a method of modeling attitude dynamics of spinning solar sail spacecraft under influence of solar radiation pressure (SRP). This method is verified and actually exploited in the operation of Japanese interplanetary solar sail demonstration spacecraft IKAROS. IKAROS shows a unique attitude behavior due to strong SRP effect. This paper shows a new attitude model of spinning sail, which is verified by flight data of IKAROS. It is also shown that the model proposed in this paper has a direct relation with the Generalized Sail Model.

Japan Aerospace Exploration Agency (JAXA) has developed the small demonstration solar sail spacecraft IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun), which will be launched in mid 2010. The main objective of this spacecraft is to deploy the 20m class sail membrane, and demonstrate the acceleration of a spacecraft by the solar radiation pressure (SRP) by means of that sail. It is important to model the SRP force adequately for the objective of navigation, especially for interplanetary spacecraft. In order to improve the model of the SRP torque induced by the sail membrane, the IKAROS project team plans to estimate the SRP torque parameters in orbit. In this paper, we present the approach to obtain the parameters needed for constructing the photon torque model through the analysis of the attitude dynamics.

JAXA launched the world's first deep-space solar sail demonstration spacecraft "IKAROS" on May 21, 2010. IKAROS was injected to an Earth-Venus trajectory to demonstrate several key technologies for solar sail utilizing the deep space flight environment. IKAROS succeeded in deploying a 20m-span solar sail on June 9, and is now flying toward Venus with the assist of solar photon acceleration. This paper describes the mission design, system design, solar sail deployment operation and current flight status of IKAROS. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

IKAROS (Inter-planetary Kite-craft Accelerated by Radiation Of the Sun) is a Small Solar Power Sail Demonstrator which deploys the membrane and generates solar power by means of thin film solar cells. IKAROS was launched by H-IIA rocket from Tanegashima Space Center on 21st May 2010 as a piggy back spacecraft of Planet-C "AKATSUKI" Venus climate orbiter. IKAROS (and also AKATSUKI) is the first spacecraft managed by JAXA (Japan Aerospace Exploration Agency)'s system safety activity at ISAS (Institute of Space and Astronautical Science). IKAROS itself has to be managed to avoid occurring the critical hazard not only to worker, rocket and facility but also to the main spacecraft AKATSUKI because IKAROS is a piggy back spacecraft. GSE (Ground Support Equipment) and operation procedures are also objects for system safety. IKAROS has several hazardous functions like a separation mechanism, an unfolding mechanism, batteries, a pressure system and so on. There is also a problem to solve as for SCC (Stress Corrosion Cracking) of aluminium alloys used for structure material. There is three or four phase for system safety management before it is allowed to bring the spacecraft to the launch site. In this paper, it is shown that how IKAROS demonstration team manage the system safety activity, which is, the design modification, the operation management, the verification experiment for hazard control. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

This paper describes the attitude dynamics and the control method of a spinning solar sail spacecraft. The solar sail considered here has no structure supporting membrane, therefore estimation of the effect of membrane flexibility is one of the problems to solve for the future validation flight. In this study, we established a dynamic model including membrane vibration to handle a coupled motion of a rigid spacecraft and a flexible membrane, and focus on the consideration of attitude control method. The result is confirmed with numerical simulation by use of Multi Particle Model(MPM).

The Japan Aerospace Exploration Agency (JAXA) will make the world's first solar power sail craft demonstrate for both its photon propulsion and thin film solar power generation during its interplanetary cruise. The spacecraft deploys and spans its membrane of 20 meters in diameter taking the advantage of the spin centrifugal force. The spacecraft weighs approximately 300kg, launched together with the agency's Venus Climate Orbiter, PLANET-C in June of 2010. This will be the first actual solar sail flying an interplanetary voyage.

Small satellites, especially pico or nano-class satellites, which can be developed in a very short period and at very low cost, are considered to provide good opportunities for technology demonstration in a space environment. Based on the success of the first pico-satellite XI-IV, which was intended to establish the basic technologies required for this class of satellites, Intelligent Space Systems Laboratory (ISSL) at the University of Tokyo developed its second pico-satellite XI-V with the mission to demonstrate new space technologies such as the verification of copper indium gallium di-selenide (CIGS) thin-film solar cells in space. The pico-satellite bus verified by XI-IV was used for this mission, so that the satellite was completed within as short a development period as one year. XI-V was launched on October 2005 and has been successfully conducting its missions. In this paper, following the introduction of the pico-satellite bus system and its demonstrated results on XI-IV, the details of the missions and on-orbit experimental results of XI-V are described.

Small satellites, especially pico- or nano-class satellites, are considered to provide good opportunity for technology demonstration. University of Tokyo's pico-satellite "XI-V", which was scheduled to be launched in September 2005, was developed in I year with the mission to test newly developed solar cells. This paper introduces the details of the mission and its effective operation using the network of ground stations. (c) 2007 Elsevier Ltd. All rights reserved.

Capture of tumbling objects in space will be one of the important on-orbit service technologies in the future. It requires a series of technologies such as camera-image tracking of the target, target attitude motion estimation, and attitude control of the chaser to approach and grasp the target. Based on theoretical and simulation-based research, the University of Tokyo successfully performed an on-orbit experiment of some of these technologies on a Japan Aerospace Exploration Agency's (JAXA, formerly NASDA) microsatellite named "mu-LABSAT." In this paper, the objectives and procedures of these experiments, the control and estimation algorithms, and the results are described.

The Moon is recognized as an important destination for space science and exploration. The National Aeronautics and Space Administration (NASA) has presented a new policy for space exploration that includes human expedition to the lunar surface. The other agencies that include the Japan Aerospace Exploration Agency (JAXA) have also planned to send spacecraft to the moon. To put the spacecraft into orbit around the moon, various methods are conceived. For example, one of them is that the special spacecraft, such as an orbital transfer vehicle (OTV), is used in each transfer segment. It is the very important thing in cost that OTV between Low Earth Orbit (LEO) and Lunar Low Orbit (LLO) is reused. To promote lunar exploration efficiently, reusable OTV between LEO and LLO is required. OTV has been studied at JAXA, which is based on further development of H-II Transfer Vehicle (HTV). The OTV system is roughly composed of the payload segment, the propulsion segment and the fuel cartridge. The payload segment is separated from OTV body on Lunar Transfer Orbit (LTO), and is transported to LLO. The propulsion segment and the empty fuel cartridge are returned to LEO through Earth Transfer Orbit. (ETO). This paper aims at improving the payload ratio of reusable OTV. In this research, we focus on optimization problems of return trajectories with small fuel consumption. Flight time in LTO should be short generally. When payload is empty, flight time isn't restricted. So, multi-impulse flight using electrical propulsion is used in ETO. Aero-assisted flight using aero-brake is also utilized near the Earth. In ETO, we discuss ballistic flight using chemical propulsion, multi-impulse flight using electrical propulsion and aero-assisted flight using aero-brake. Optimal return trajectories of OTV between the Earth and the Moon are proposed. This research can be also extended to the transfer vehicles between the Earth and the Lagrange point of Sun-Earth system. The L2 point in the Sun-Earth system may be utilized for a space port for the outer planets exploration in the future. In this paper, we show the concept of the OTV system and the result of the optimal return trajectories for OTV.

2003年6月30日,東京大学中須賀研究室が開発した超小型衛星CubeSat-XI(1kg,10cm立方)がロシア連邦プレセツクより高度820kmの太陽同期軌道に打ち上げられた.その後,当初の予想を超え1年以上の長期にわたり順調に動作し,バス機器の軌道上実証,画像取得・ダウンリンクなどの実験を行って大きな成果を収めた.この衛星は学生の手作りにより開発された衛星で,その第一の目的は宇宙工学教育であるが,民生品をベースに低コスト・短期に衛星を提供することによる新しい宇宙開発を試行することをその先の目的としている.本論文では,CubeSat-XIの概要と軌道上実証の成果を述べ,その開発経験や成果を踏まえ,宇宙開発の低コスト化・短期開発化を目指した小型・超小型衛星開発のあり方を論じる.

On a NASDA's microsatellite named "μ-LABSAT," which was launched by H-IIA on December 14, 2002 (Fig.1), Communications Research Laboratory (CRL), National Aerospace Laboratory (NAL) and University of Tokyo (UT) have been jointly performing several orbital experiments as technology demonstration towards the future orbital servicing missions. In University of Tokyo's experiment which was held on May 14, 2003, the micro-satellite released a small object named "target," and its rotational motion was estimated by the images captured continually using a camera developed by CRL. Then satellite attitude control was performed by visual feedbacks of the target image position on the camera frame so that the target image may come to a certain point on the camera frame. This is a pre-experiment of so-called LOS (Line Of Sight) control, which will be indispensable during rendezvous and docking to the satellite to be serviced. In this paper, the objectives and procedure of these experiments, and the results will be described. Copyright © 2003 by the International Astronautical Federation. All rights reserved.