川口 淳一郎

The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.

工学実証を目的に2003年5月に打ち上げられた「はやぶさ」は,小惑星イトカワへの着陸を経て,2010年6月13日,オーストラリアに帰還し,試料カプセルを無事回収することに成功した.本報告は,その帰還,再突入における飛行運用を紹介する.

小惑星探査機「はやぶさ」は2010年6月13日にオーストラリアに帰還し,試料カプセルを無事回収することに成功した.これに先立ち2010年4月以降,合計5回の軌道制御により,地球をフライバイする軌道からオーストラリアに帰還する軌道へと精密誘導を実施した.本報告は,誘導計画立案に新たに導入したパラメータを紹介し,このパラメータを用いた計画立案手法について解説する.

Hayabusa Sample Return Capsule (SRC) has accomplished reentry flight directly from the interplanetary-transfer orbit with velocity of about 12 km/s and successfully recovered on June 14, 2010. The SRC is considered to deploy parachute at the altitude of 5 km as planned, while the chute-trigger timer has been carefully set to cover contingency cases due to malfunctions of triggering devises taking account of dispersions of orbital and atmospheric density and errors in the aerodynamic coefficients. All the components separated at the chute-deployment were searched-out based on the landing position of the instrument module.

The Japan Aerospace Exploration Agency (JAXA) has been developing lithium-ion secondary cells for aerospace applications. Lithium-ion secondary cells were first used for the interplanetary spacecraft, HAYABUSA. For the long-term operations on the moon and interplanetary orbit, in-orbit performance of the lithium-ion battery demonstrated by HAYABUSA has been precisely examined. Furthermore, the regenerative fuel cell system is also one of the most important candidates to the future lunar and planetary missions where the higher energy density is required.

In this paper, we consider constellation of two orbiters around the Mars. We assume two orbiters, whose orbits are required to be orthogonal. After Mars orbit insertion, it will be needed to adjust their orbital planes appropriately for required configuration under perturbation. We discuss how to transfer S/C to the seperated orbits after simultaneous insertion, and how to maintain these orbits during the mission phase. We adopt the frozen orbit for one orbiter to fix the orbit axis, and utilize J2 perturbation on the argument of periapsis or the right ascension of ascending node for keeping the orthogonality between two orbital planes. Maneuver plan is also reported.

Preliminary feasibility assessment of a Martian nonstop sample return system has been conducted as a part of Mars Exploration with Landers and Orbiters (MELOS) which is currently under investigation in Japan Aerospace Exploration Agency. In the mission scenario, an atmospheric entry vehicle of aero-maneuver ability is flown into the Martian atmosphere, collects the Martian dust particles and atmospheric gases during the hypersonic atmospheric flight, exits the Martian atmosphere, and is inserted into a parking orbit from which a return system departs for the earth. In order to accomplish controlled flight and successful orbit insertion, aerocapture technologies are introduced into the vehicle guidance and control system. A conceptual design is presented as a result of the preliminary system analysis.

Japan has launched many interplanetary spacecraft for exploration of solar system bodies including Mars. Now we are planning the next Mars mission in the late 2010's. This paper describes the preliminary mission analysis and orbit design for this plan. The combined exploration by several spacecraft requires complicated and careful consideration, different from those for single-probe missions. Mission plans to realize required configuration by a single launch and simple simulation results are reported.

The Japan Aerospace Exploration Agency (JAXA) will make the world's first solar power sail craft 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). The spacecraft deploys and spans a membrane of 20 meters in diameter taking the advantage of the spin centrifugal force. The spacecraft weighs approximately 310kg, launched together with the agency's Venus Climate Orbiter, AKATSUKI in May 2010. This will be the first actual solar sail flying an interplanetary voyage.

The solar sailing spacecraft is one of the promising propulsion systems for the future deep space exploration mission. Japan Aerospace Exploration Agency (JAXA) has been studying the spin solar sail spacecraft which has a squared-shape type solar sail. One of the most significant objective to control the satellite orbit of the spacecraft is to estimate the thrust force induced by the photon, namely to establish the acceleration model before the launch. In a view point to use this model in orbit, the calibration of the acceleration model and evaluation of the dynamics on orbit are also important issue. This paper presents the way to construct the acceleration model of the Solar Radiation Pressure (SRP) on ground, and the calibration and evaluation strategy for this model by using the on-orbit data.

Marco Polo is a mission to return a sample from a near-Earth object of primitive type (class C or D). It is foreseen as a collaborative effort between the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency (ESA). Marco Polo is currently in a Phase-A study (status as of summer 2009). This paper focuses on the scientific requirements provided to the industrial study consortia in Europe as well as the possible mission scenario at the target object in order to achieve the overall mission science objectives. The main scientific reasons for going to a near-Earth object are to...