Advanced technologies applied to "HAYABUSA" asteroid explorer

The "HAYABUSA" asteroid explorer has completed the interplanetary space cruising using the ion engine (IES) and arrived at the asteroid "ITOKAWA" in this September. The primary objectives of the program are to demonstrate some key technologies which are all requisite for future scientific missions, and to bring back the world's first sample from a near Earth asteroid. In the cruising phase, distance between the explorer and Sun varied from 0.86 to 1.7 AU and the maximum interval from Earth reached up to 2.33 AU. The explorer system possesses the capability to adapt to such wide changes of electrical power and thermal condition in order to operate IES continuously. In the mission phase, the explorer will rendezvous with the asteroid and touch-down autonomously over 2.0 AU apart from Earth. In order to fulfill these tough requirements under limitations of satellite mass and electrical power, a lot of technologies are developed and "packed in" only 510 kg of small satellite body for the ambitious mission. It has already demonstrated the new technologies through the cruising phase operation successfully. At present HAYABUSA is on challenging to rendezvous and sample.