In-orbit experiment of HAYABUSA onboard navigation function during Earth swing-by operation

The engineering test spacecraft HAYABUSA was successfully launched on May 9th, 2003 and it is now on the way to the asteroid ITOKAWA. The spacecraft has some autonomous navigation functions such as relative position keeping around the asteroid, decent toward the asteroid surface, the synchronization with the surface for safe touch-down and sampling. This paper describes the onboard navigation function of HAYABUSA briefly and shows some in-orbit test results, especially the experiment using the Moon and the Earth during Earth swing-by operation in May, 2004.