船瀬 龍

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.

IKAROS is the Japanese deep-space solar sail technology demonstration mission launched in 2010. IKAROS is a spinner spacecraft with the 20m-span solar sail kept extended by the centrifugal force. During its solar sailing flight from Earth to Venus, IKAROS showed a unique attitude behavior due to solar radiation pressure attracted on the sail. This paper proposes a generalized model of spinning sail-craft, which clearly explains the attitude behavior observed in IKAROS. Then it is shown that this behavior has a clear dependency on the sail shape and the optical property distributions on the sail. We show the estimation results of the on-orbit sail shape using this new model. Copyright © 2011 by Yuichi Tsuda.

In this paper, the attitude dynamics of IKAROS, which is spinning solar sail, is presented. Multi Particle Model (MPM) and First Mode Model of out-of-plane deformation (FMM) are introduced to analyze the out-of-plane oscillation mode of spinning solar sail. Considering the thruster configuration of IKAROS, the force on main body and membrane by thruster plume as well as reaction force by thruster are integrated into MPM. The attitude motion after sail deployment or reorientation using thrusters can be analyzed by MPM numerical simulations precisely. The out-of-plane oscillation of IKAROS is governed by three modes derived from FMM. FMM is simple and valid for the design of attitude controller. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

This paper discusses about attitude dynamics for spinning spacecraft under influence of solar radiation pressure (SRP). Generally spinning objects maintain its spin axis with reference to inertial frame. But if disturbance torque like SRP affects this object, the spinning motion indicates a unique behavior due to dynamical coupling between the SRP torque and the spin motion. IKAROS and HAYABUSA launched by Japan Aerospace Exploration Agency (JAXA) positively utilize this phenomenon in actual operation. For example, HAYABUSA was kept sun-oriented during spin stabilized phases without fuel utilizing this effect. In the IKAROS mission a method has been developed which controls both attitude and orbital trajectory by SRP. These two are the remarkable examples of how SRP is utilized for fuel-saving and efficient operation. To enable to this technique, it is essential to understand attitude dynamics including SRP influence correctly. In past papers, simplified attitude models including SRP effect are derived both for HAYABUSA and IKAROS missions. These models are cable of explain wide range attitude motions. But in the flight data of HAYABUSA and IKAROS, there are remarkable motions that these simplified models cannot explain. In past papers, these motions called wind mill effect and spiral behavior. There are two purposes in this paper. The one is alignment of microscopic theory and macroscopic theory. The other one is considering these remarkable motions theoretically. For these purposes, we construct FEM model including SRP effects and simulate attitude dynamics numerically. In the results of simulations, two causes were found. The one is optical property of surface. The other one is non-flat surface effect of spacecraft. In this paper, we indicate the background of constructing SRP model and the evaluation including flight data of HAYABUSA and IKAROS. Then we discuss about the relationship between simplified attitude models and microscopic models. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

Japan Aerospace Exploration Agency (JAXA) successfully achieved the world's first solar power sail technology by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) mission in 2010. It demonstrated a photon propulsion and thin film solar power generation during its interplanetary cruise. The 200m2-span sail was deployed and kept extended by centrifugal force of the spacecraft rotation. IKAROS also succeeded in accelerating and controlling the orbit by actively exploiting solar radiation pressure, and thus became the world's first actual solar sailer flying an interplanetary voyage. This paper presents the design of IKAROS solar sail system, operation results and introduces a perspective of this new technology to apply to the next generation mission toward Jupiter and Trojan asteroids.

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. MAROS 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 MAROS. It is also shown that the model proposed in this paper has a direct relation with the Generalized Sail Model.

The Japan Aerospace Exploration Agency (JAXA) makes the world's first solar power sail craft IKAROS demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise. The spacecraft deploys and spans a membrane of 20 meters in diameter using the spin centrifugal force. It also deploys thin film solar cells on the membrane, in order to evaluate its thermal control property and anti-radiation performance in the real operational field. The spacecraft weighs approximately 310kg, launched together with the agency's Venus Climate Orbiter, AKATSUKI on May 21, 2010. This paper presents the summary of development and operation of IKAROS.

ソーラーセイルWG では,太陽の光子の圧力を受けて進む光子セイルに,薄膜太陽電池を貼り付けて大電力を発生し高比推力のイオンエンジンを駆動する推進システム,ソーラー電力セイルの検討を進めている.このシステムの確立において重要な技術課題である大型膜面の展開機能を検証するため,大気球を用いた大型膜面の展開総合実験を計画し,展開システムの開発を行った.あいにく実験場の天候不良により平成20 年度に続き,放球を実施できなかったが,本論文では,この実験の内容および位置付けについて紹介する.

This paper investigates the solar sail modeling and its estimation approach of solar power sail spacecraft IKAROS. Estimation of solar sail force model in space is the key factor for successful solar sail navigation because the solar sail have large uncertainty due to the flexible membrane. Since the sail wrinkles after the deployment and its surface will suffer from degradation, the solar sail force model is difficult to develop before the launch. In this paper, a practical analysis of estimating the solar sail force model from radiometric tracking data is investigated. This is demonstrated by orbit determination including parameter estimation of generalized sail model.

This paper introduces new attitude control system for solar sail which leverages solar radiation pressure and achieves completely fuel-free and oscillation-free attitude control of flexible spinning solar sail. Novel attitude control device was developed, which is a thin film-type device and can electrically control its optical parameters such as reflectivity to generate unbalance of the solar radiation pressure applied to the edge of the sail. By using this device, minute and continuous control torque can be applied to the sail so that very stable and fuel-free attitude control of large and flexible membrane is realized. The control system was implemented as an optional attitude control system for small solar power sail demonstrator IKAROS. On-orbit attitude control experiments were conducted and the performance of the controller was successfully verified compared with the ground-based analytical performance estimation. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

宇宙システムにおいて画像のもつ可能性は非常に大きく,画像はミッションを遂行する上で必要不可欠な情報である.しかし従来搭載されてきたカメラシステムは,視点が固定されている場合が大半であり,監視対象が巨大な場合には,全体を観測することが非常に困難であるという問題があった.そこで今回我々は,大型の展開構造物を監視する用途向けに,固定カメラヘッダ4台と非回収発射型の分離プローブカメラ1台から構成される,プローブ分離型搭載カメラシステムを開発した.本稿では,このプローブ分離型カメラの電気システム構成について詳しく議論する.

As many varieties of microsatellite missions have been purposed, microsatellite's performances are becoming higher level. It is important to develop higher level 3-axis attitude control mechanics. We purpose an innovative 3-axis attitude control for microsatellite by using Reflectivity Control Device, RCD which is capable of changing its reflectance by imposed voltage. This paper shows one example of 3-axis attitude control using RCD, and advantages of this method by being compared to non RCD methods which used only reaction wheel.

In this paper, the attitude motion and attitude control strategy of spinning solar sail are discussed. As the spinning type solar sail does not have any rigid structure to support its membrane, the impulsive torque by the RCS can introduce oscillatory motion of the membrane. Thus, an "oscillation free" attitude controller is needed, which takes into account the flexibility of the membrane and avoid unnecessary oscillatory motion. First, the dynamics model and numerical model were introduced, and the validity of these models and dominant out-of-plane membrane vibration mode is examined by membrane vibration experiment and comparison between both models. Then, based on the analysis of the dynamics of torque-free motion, it was shown that a spinning solar sail has three oscillation modes of nutation, one of which is equal to the spinning rate of the spacecraft. The dominancy of each nutation mode was analytically and numerically discussed. Then, we discussed the spin axis maneuver control using conventional RCS. It was analytically shown that continual impulsive torque synchronizing the spin rate can excite nutation velocity and that a controller is needed to damp the nutation while controlling the spin axis at the same time. The authors proposed new controller named Flex-RLC and improved one. Their effectiveness was verified by numerical simulations using precise multi-particle numerical model which can express higher order oscillatory motion of the flexible membrane, and it was found that the proposed method can control the attitude of spinning solar sail while drastically reduces the nutation velocity compared with conventional control logic. So, it can 983 be said that the proposed method is promising fast and stable controller for spinning solar sail.

It is becoming imperative to have visual capabilities for space activities. We have developed a very small, high-performance image processing unit that is based on COTS technologies. It has a 500 MIPS calculation capability in a single, 50 mm x 50 mm printed circuit board, and it incorporates various types of interfaces using field-programmable gate array (FPGA) technology. The camera is called the high-performance image acquisition and processing unit (HPIMAP). The HP-IMAP technologies are being utilized in the IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun) that was launched May 21, 2010. In this article, we describe the HPIMAP and technical demonstration in IKAROS mission.

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 MAROS 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.

This paper investigates the solar sail modeling and its estimation approach of solar power sail spacecraft IKAROS. Estimation of solar sail force model in space is the key factor for successful solar sail navigation because the solar sail have large uncertainty due to the flexible membrane. Since the sail wrinkles after the deployment and its surface will suffer from degradation, the solar sail force model is difficult to develop before the launch. In this paper, a practical analysis of estimating the solar sail force model from radiometric tracking data is investigated. This is demonstrated by orbit determination including parameter estimation of generalized sail model.

The Hayabusa spacecraft embarked on its return trajectory to Earth, after its touchdown on the asteroid Itokawa. During the cruise phase Sun-pointing mode, the spin-axis of the Hayabusa performs a coning motion under the solar radiation pressure effects. The effect mainly originates from the diffuse reflection of the solar radiation pressure on the solar array panels. In the simple analysis of this coning motion, however, the diffuse reflection coefficient is inconsistent in comparison to the typical diffusive parameter of the solar array panel. This discrepancy must be clarified by constructing a more accurate model of the solar radiation pressure in order to be able to dissolve the uncertainty during the return phase of the Hayabusa spacecraft. The accurate model should also be able to support the extremely precise navigation during the return phase to the Earth. This paper presents the precise model of the solar radiation pressure of the Hayabusa spacecraft and the estimation method for obtaining the optical parameters of the solar radiation pressure model.

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 315kg, launched together with the agency's Venus Climate Orbiter, PLANET-C in 2010. This will be the first actual solar sail flying an interplanetary voyage.

Solar sail is one of the promising propulsion systems for future deep space exploration missions as it does not require any fuel to acquire propulsive force. However, the attitude control system of the solar sail, which controls the direction of the sail and thus the propulsive force, has not been much studied, although this constitutes the essential part of the orbital control using solar sail. This paper discusses the attitude dynamics and the control method of a spinning type solar sail spacecraft. The spinning type solar sail has no rigid structure supporting its membrane. This type of mechanism has the advantage in its simple and lightweight structure, however, the attitude control is difficult due to the flexibility of the membrane. In this paper, we introduced a mathematical dynamics model including first vibration mode of the membrane which can handle coupled motion of a rigid spacecraft and a flexible membrane, and analytically developed a controller that can avoid unnecessary oscillatory motion. The performance of the controller and the effect of solar radiation pressure, which can deform the membrane of solar sail, on the controller were verified by numerical simulations using more precise multi-particle numerical model.

This paper describes the attitude dynamics of spacecraft with large flexible structure, such as huge antenna or membrane of solar sail. The coupled motion of the rigid spacecrafts with the flexible structure is complicated, and it is important to predict the motion for the design of configuration or operation planning. It requires a lot of time to calculate the motion of the flexible structure by numerical simulation, and the analysis using simple model is important for exhaustive validation. In this study, a simplified model of the attitude dynamics considering the first vibration mode of flexible structure is introduced. Using this model, the vibration mode of the attitude motion of spacecraft is analyzed. The result of the analysis is confirmed with numerical simulation and compared with the result obtained by use of proven model.

This paper deals with how the formation flight target is expressed as trivial in some appropriate coordinates, instead of an orbital target. There is attempted to show the regularization process to obtain a special coordinate through a Levi-Civita non-linear transform. The paper will show how and which the virtual target corresponds to the physical formation configuration.