川勝 康弘

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.

Reported in this paper are the results of a mission analysis conducted for an asteroid exploration mission. Following the results obtained from HAYABUSA, a Japanese asteroid explorer, the Japan Aerospace Exploration Agency has started studying the possibility of the next asteroid exploration mission. The mission studied gives priority to the early retrieval of a sample from an asteroid with a primitive composition. Therefore, the design of the spacecraft follows that of the HAYABUSA, basically as it is, and the spacecraft is planned to be launched early in the next decade. The objective of the mission analysis is to design a mission sequence which has a launch window early in the next decade, is feasible utilizing a HAYABUSA-type spacecraft, and whose target asteroid complies with the scientific objectives. The results include the selection of the target asteroid, the design of the nominal mission sequence, and the alternative sequence to overcome the drawbacks of the nominal sequence.

Reported in this paper are the results of the orbit maneuver compensation in KAGUYA's Lunar transfer. Because of the uncoupled allocation of the attitude control thrusters, extra velocity increment (δv ) is induced whenever KAGUYA performs an orbit maneuver. Since the observed level of δv was unacceptable range from the point of maneuver accuracy requirement, it was compensated by means of deducting estimated δv from the orbit maneuver command. The δv estimation model was updated step-by-step during the Lunar transfer, which leaded to significant improvement of the orbit maneuver accuracy and resulted in the omission of the last trajectory correction maneuver. The method of the compensation and its results are introduced in detail.