spacetoday.net: Japanese asteroid probe encounters problems

Posted: Sat, Oct 8, 2005, 12:16 PM ET (1616 GMT)
Hayabusa spacecraft illus. (JAXA)

A Japanese spacecraft approaching an asteroid has lost a key component of its attitude control system, raising questions about its ability to carry out its mission. The y-axis reaction wheel on Hayabusa, a device used to help maintain the spacecraft's proper orientation, failed on October 2, the Japanese space agency JAXA said this week. The spacecraft's x-axis reaction wheel failed in late July. Right now the spacecraft is using its one remaining reaction wheel, along with reaction control thrusters, to orient itself. Spacecraft engineers are studying how to maintain control of the spacecraft in this mode while minimizing the use of thruster propellant. The spacecraft has been in a stationkeeping mode about 7 kilometers from the asteroid Itokawa, and plans to perform two landings, collecting samples to return to Earth; the reaction wheel failures, though, may mean than only one such landing will be attempte