森 治

This paper proposes a method to store a large solar-sail membrane while ensuring repeatability of its stored configuration. The feasibility and effectiveness of the method is verified through a series of sail-storage experiments using 10m-size membranes. Large membranes used as a solar sail should be stored compactly to save the launch volume; in addition, their stored configuration should be sufficiently predictable in order to guarantee reliable deployment in orbit. However, it is difficult to store a large membrane compactly with sufficient repeatability because of the finite thickness of the membrane. This paper classifies the existing and proposed folding patterns that can consider the finite-thickness of membranes. This paper then demonstrates the feasibility of "bulging roll-up" experimentally, and evaluates the repeatability of its stored configuration quantatively. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

The world's first solar sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) which is operated by Japan Aerospace Exploration Agency (JAXA) lost communication with the ground station due to the power shortage on December 24, 2011. In order to acquire IKAROS again after the power comes back, we immediately initiated to predict the attitude and orbit for the spacecraft. As the result of the effort for the prediction, finally we acquire IKAROS after 9 months. This paper presents that the attitude and orbit prediction technique, while IKAROS was lost in space. © 2013 2013 California Institute of Technology.

An inspection of nano-probe, or deployable camera(DCAM) for a solar sail demonstrator IKAROS is developed in order to monitor the IKAROS deployable large membrane on orbit to Venus in space, and it is world first success to take picture of the satellite In this paper, we show the result of the 3 dimensional reconstruction of the membrane shape using renormalization technique for removing statistical bias We also describe the verification test at the ground using proto-type model of DCAM We make sure of the method of the analysis of membrane shape in this test

Japan Aerospace Exploration Agency (JAXA) launched the solar power sail orbiter "Interplanetary Kite-craft Accelerated by Radiation Of the Sun: IKAROS", on May 21st, 2010. IKAROS was launched by H-IIA 17th vehicle with "Venus Climate Orbiter: AKATSUKI". IKAROS demonstrates a new propulsion technology of utilizing photons from the sun for deep space exploration, which is called the Solar Power Sail technology. In a case of the solar system exploration, an ion-propulsion engine is effective as a main propulsion system because it has high specific impulse and it can provide a continuous acceleration. However, the ion-engine needs high electric power in proportion to its performance. The solar power sail technology can be a hybrid engine, which can provide high electric power generated by very thin flexible solar arrays attached on the solar sail, while obtaining acceleration generated on the solar sail by the sun radiation. IKAROS succeeded in deployment the solar power sail in an interplanetary orbit, on June 9th, 2010, the first in the world, and we could obtain various flight data of the solar power sail deployment mission, and. In this paper, we will introduce a detail of our estimation method by using monitor camera images and separation camera images. Furthermore, we will report the shape estimation results using calibrated images and luminance information of every pixel. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

This paper describes an analysis for the membrane dynamics and deformation of solar power sail demonstrator "IKAROS". After the successful deployment of membrane, some images of the whole sail membrane of IKAROS were taken by separation cameras. From these data, it has estimated that the membrane of IKAROS had a deformation different from the prediction considering the solar radiation pressure. In this paper, these observed deformations of membrane are reported and compared with the results of numerical simulation using multi-particle model. A membrane's deformation over time observed in the images taken by side monitor cameras is also reported and the cause of the changing is discussed. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Solar power sail is a deep space probe to be powered by hybrid propulsion of solar photon acceleration and ion engines to explore outer planetary region of the Solar System without relying on nuclear technology. The Japan Aerospace Exploration Agency (JAXA) launched the world's first deep space solar sail demonstration spacecraft "IKAROS" (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) on May 21, 2010. IKAROS succeeded in deploying a 20m-span solar sail on June 9 and demonstrated several key technologies for solar sail utilizing the deep space flight environment. JAXA is currently studying an outer solar system exploration mission using the demonstrated solar power sail technology. The mission plans to fly for Jupiter, where the spacecraft drops a tiny Jovian probe and performs a swing-by for a Trojan asteroid. Current scenario consists of the rendezvous with one of the Trojan asteroids that are at the Lagrange points L4/L5 associated with Sun-Jupiter system. About as large as 50m sail should be deployed for this mission according to preliminary mission analysis and related research is intensively being carried out in JAXA. JAXA plans to initiate the project in a few years and looks at the launch around 2020. © 2012 by JAXA.

It is well known that the thrust force of the solar sail due to the solar radiation pressure is changed by the orientation of the sail with respect to the Sun direction. Therefore, the orbit of the 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 succeeded to become the world's first flight solar sail in orbit. The IKAROS attitude, i.e. the spin-axis direction is nominally controlled by the rhumb-line control method. By utilizing the solar radiation pressure (SRP) torque, however, we are able to change the direction of the spin-axis only by controlling its spin rate. This is because the spin axis direction relates to the balance between the angular momentum of spinning and the SRP torque. Thus, we can control the solar sail's orbit by controlling the spin rate. The main objective in this study is to construct the orbit control strategy of the spinning solar sail via the spin rate control.

Japan Exploration Agency (JAXA) launched a powered solar sail "Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS)" on May 21, 2010. One of the primal technologies demonstrated at IKAROS is the deployment of the sail whose diameter is 20m class. After the launch, IKAROS performed the deployment sequence and have confirmed that the membrane was successfully expanded. In this paper, the flight data and observed dynamic motion via deployment are reported. These are compared with the results of numerical simulations using multi-particle model, and the accuracy and availability of this model is discussed. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

Japanese spin-type solar power sail KAROS was launched in May 21 st, 2010 by JAXA, and the 20m-sized sail membrane with 7.5μm thickness was successfully deployed in last June. During the design and development process of the sail membrane structure in last three years, the nonlinear finite element elasto-dynamics code named NEDA has been improved for the prediction of the deployment motion of the sail membrane of IKAROS. The formulation of the dynamics in NEDA is based on the energy momentum method (EMM), which preserves the total energy, the linear momentum and the angular momentum. In this paper, the theory of the finite element dynamics implemented in NEDA is summarized and the mathematical model of the deployment dynamics of IKAROS is shown in detail. The numerical result is compared with the flight data, which shows the proposed numerical method is available for the prediction of the nonlinear motion of gossamer structures. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

Japan Aerospace Exploration Agency (JAXA) launched the solar power sail orbiter "Interplanetary Kite-craft Accelerated by Radiation Of the Sun: IKAROS", on May 21st, 2010. IKRAROS was launched by H-IIA 17th vehicle with "Venus Climate Orbiter: AKATSUKI". IKAROS demonstrates a new propulsion technology of utilizing photons from the sun for deep space exploration, which is called the Solar Power Sail technology. In a case of the solar system exploration, an ion-propulsion engine is effective as a main propulsion system because it has high specific impulse and it can provide a continuous acceleration. However, the ion-engine needs high electric power in proportion to its performance. The solar power sail technology can be a hybrid engine, which can provide high electric power generated by very thin flexible solar arrays attached on the solar sail, while obtaining acceleration generated on the solar sail by the sun radiation. IKAROS succeeded in deployment the solar power sail in an interplanetary orbit, on June 9th, 2010, the first in the world, and we could obtain various flight data of the solar power sail deployment mission. We report the details of the mission system of IKAROS that applying a new deployment method, and the flight data obtained actually from IKAROS in inter-planetary orbit. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

The Solar Sail "IKAROS" (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), which is the first solar sail on orbit, consists of 20m diagonal length square membrane made of 7.5mm thickness polyimide film. The sail membrane is deployed by centrifugal force due to spinning motion of the spacecraft. The wrapping fold is applied to realize stable deployment property. The manufacturing process of the large membrane with the folding techniques are described in detail. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

The small solar power sail demonstrator Ikaros successfully deployed its sail by a nominal sequence, which consists of two stages. However, in case of anomaly of the deployment mechanism, a one-step dynamic deployment of the sail might be employed as a contingency plan. This paper proposes a spin-up control scheme that enables the one-step deployment of Ikaros's sail, and evaluates the controlled responses using a numerical multi-particle model. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

After deployment of the IKAROS solar sail in June 2010, a small ejectable camera, DCAM2, was released from the spacecraft to provide external imagery and verification of full sail deployment. In this paper we analyze the images taken by the DCAM imager and attempt to use them as a measurement source to supplement the known initial parameters to reconstruct the trajectory of the micro-spacecraft. Further complicating this analysis is the requirement that IKAROS is required to spin to maintain sail shape. Though spinning stretches the sail flat, the sail is also warped due to the solar pressure exerted upon it. The second goal of the analysis is to attempt to estimate the warping of the sail due to this pressure. The contributions of this paper cover several areas: 1) A method is provided to reconstruct the DCAM imager trajectory using a small number of photos as the sole measurement device; 2) An estimate of sail warping is provided giving some indication of total solar pressure enacted upon the sail; 3) Recommendations for the design of future external imagers of solar sails and other structures are given based on the difficulties in carrying out this analysis.

Japanese spin-type solar power sail IKAROS was launched in May 21st 2010 by JAXA, and the 20m-sized sail membrane was successfully deployed in June 2010. The deployment was achieved through two stages. In the first stage, a part of the membrane is unwrapped quasi-statically from the cylindrical spacecraft. In the second stage, the whole membrane is deployed dynamically from the spacecraft. During the design and development process of the sail membrane structure in last three years, the numerical simulation of the deployment dynamics had been one of the most important issues. In this paper, the pre-flight prediction of the deployment behavior in the second stage is summarized, and the flight data is compared with the numerical simulation.

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.

This study aims at finding structural parameters as well as control laws that enable spin-stabilized spacecraft to deploy large membranes or cable-webs in a single step. If the structures/controllers are not properly designed, the deployed elements may re-wrap around the hub after deployment, which may cause entanglement; in addition, the nutation dynamics of the system may become unacceptably large during/after the deployment. In order to develop a reliable strategy for single-step deployment, this study carries out a series of three-dimensional transient analyses of spin deployment, using a simple analytical model that allows for the nutation dynamics of the spacecraft. The analytical model consists of a rigid body and four cables with tip masses. The analysis results lead to the proposal of the structural/controller-design criteria. Finally, the applicability of the proposed design criteria is evaluated using a more practical solar sail model, in which membranes are modeled as mass-spring networks. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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.

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.

The present study develops a new three-dimensional Timoshenko beam finite element (FE) whose length can be varied during transient dynamic analyses. The variable-length element enables the dynamic deployment analysis of exible appendages with non-negligible bending stiffness. In addition, the developed scheme employs an implicit time integration whereby energy and momentum in the system is properly conserved, and no artificial numerical damping is introduced. As a result, the scheme makes it possible to evaluate the impact of structural damping on the system's dynamics. The developed beam element is then used in an FE model of a solar sailcraft currently developed in Japan, and its deployment dynamics is analyzed allowing for the bending stiffness of the bundled membranes, as well as the effect of some realistic design imperfections. © 2009 by the American Institute of Aeronautics and Astronautics, Inc.