Yuya Mimasu

Generalized Attitude Model for Spinning Solar Sail Spacecraft

An attitude model for a general spinning solar sail spacecraft under the influence of solar radiation pressure is presented. This model, called “Generalized Spinning Sail Model”, can be applied to realistic sails with nonflat surfaces that have nonuniform optical properties. The unique behaviors predicted by the generalized spinning sail model are verified by actual operation of the Japanese spinning solar sail spacecraft IKAROS. It is shown how imperfections in the sail surface affect the attitude motion of spinning sails, and a compact mathematical model that can precisely reproduce the spin-averaged motion of the spinning sails is derived. The stability conditions and a reduced model that preserves the key characteristics of the generalized spinning sail model are also derived to reveal the unique properties of the attitude behavior of spinning sails.

Generalized Attitude Model for Momentum-Biased Solar Sail Spacecraft

This paper describes a method of modeling general attitude dynamics of a nonspinning momentum-biased spacecraft under strong influence of solar radiation pressure. This model, called the “generalized sail dynamics model,” can be applied to realistic solar sail spacecraft with nonflat surfaces and nonuniform optical reflectance. A coarse sun-pointing momentum-biased spacecraft is especially of interest, for which an approximate solution of the equations of motion is analytically derived. Stability and fundamental characteristics of momentum-biased spacecraft dynamics as well as theoretical relations with past dynamics models are discussed in detail. Furthermore, unique attitude motion predicted by the novel model is verified with flight data of the Japanese interplanetary probe, Hayabusa 2.

Overview of IKAROS Mission

The Japan Aerospace Exploration Agency (JAXA) makes the world’s first solar power sail demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). It deployed and spans a membrane of 20 m in diameter taking the advantage of the spin centrifugal force. It accelerates and controls the orbit using solar radiation pressure successfully. This is the first actual solar sail flying an interplanetary voyage. This paper presents the summary of development and operation of IKAROS.

Hybrid Estimation of Solar Radiation Pressure for a Spinning Solar Sail Spacecraft

Nomenclature A = reference area, m a1;2;3 = characteristic optical sail coefficients B = Lambertian coefficients FXSF = transverse component of the solar radiation pressure force acting on the sail, N FZSF = normal component of the solar radiation pressure force acting on the sail, N h = offset, m k1;2 = solar radiation pressure torque coefficients P = solar radiation pressure, N∕m R = sail radius, m s = fraction of specular reflection TSRP = solar radiation pressure torque, N · m α = right ascension of the spacecraft spin axis, deg βS = solar cone angle, deg δ = declination of the spacecraft spin axis, deg e = sail’s firm emissivities η = deflection angle of the sail from the spin plane, deg ξ = torsion angle of local elements of the sail, deg ρ = reflection coefficient

Shape Parameters Estimation of IKAROS Solar Sail Using In-Flight Attitude Determination Data

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.

Fast estimation of asteroid shape and motion for spacecraft navigation

In this paper, we consider fast simultaneous estimation problem of the geometric shape of the asteroid and the relative motion of the spacecraft. In asteroid exploration missions, the information of asteroid shape and motion is needed to find suitable landing sites and navigate the spacecraft safely. In the previous HAYABUSA mission, large part of the estimation was performed manually by ground operators. We propose an efficient automatic estimation method using the image feature matching and matrix decomposition based fast 3D reconstruction techniques. Preliminary experiment results are also shown.

Solar Radiation Pressure-Assisted Fuel-Free Sun Tracking and Its Application to Hayabusa2

This paper describes the modeling, dynamical characteristics, and implementation of an attitude control method that actively uses solar radiation pressure. The theory behind this control method is ...

Simultaneous estimation of shape and motion of an asteroid for automatic navigation

In an asteroid exploration and sample return mission, accurate estimation of the shape and motion of the target asteroid is essential for selecting a touchdown site and navigating a spacecraft during touchdown operation. In this work, we present an automatic estimation method for the shape and motion of an asteroid, which is planned to be tested in future exploration missions including Japanese Hayabusa-2 [1]. Our task is to estimate the shape and rotation axis of the asteroid, as well as positions of the spacecraft from optical images. The proposed method is based on the expectation conditional-maximization (ECM) framework that consists of an auxiliary particle filter and nonlinear optimization techniques. One of our technical contributions is the estimation of the direction of rotation axis of the asteroid from monocular camera images, which are taken by the moving spacecraft. We conducted two experiments with synthetic data and an asteroid mock-up to show the validity of the proposed method and to present the numerical accuracy.

Attitude and Orbit Prediction of IKAROS in Actual Flight Operation

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 short-age 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.

Model Predictive Control of Hayabusa2 Probe in the Approach Phase to an Asteroid

Abstract A new asteroid exploration spacecraft “Hayabusa2” as a follow on of “Hayabusa” is now in the course of production and experiment in order to launch in 2014. The touchdown of Hayabusa2 can be split into two phases, i.e., the approach phase and the final descent phase. In the approach phase, the spacecraft is guided and controlled by based on the command from the ground station. In contrast, the spacecraft controls its position and attitude by based on the autonomous computation in the final descent phase. This paper presents the application of the Model Predictive Control (MPC) to the approach phase to the asteroid, and verifies the performance and feasibility of this control algorithm through numerical simulations.