Assessment of plasma interactions and flight status of the HAYABUSA asteroid explorer propelled by microwave discharge ion engines

Microwave discharge ion engines '[micro]10' are dedicated to the main propulsion on the HAYABUSA asteroid explorer. In a development program, various tests and assessments were conducted on the ion engines and the spacecraft. They include endurance tests, an electromagnetic interference susceptibility test, an interference test between the plasma and communication microwave, a beam exhaust test on the spacecraft, assessments on the plasma interference with a solar array, and so on. The spacecraft was launched in deep space by the M-V rocket in May 2003. After vacuum exposure and several runs of baking for reduction of residual gas, the ion engine system established continuous acceleration of the spacecraft toward the asteroid ITOKAWA. The spacecraft passed through a perihelion of 0.86 astronomical unit (AU) in February 2004 and an aphelion of 1.7 AU in February 2005, becoming the first solar electric propulsion system to travel this far toward and away from the Sun. The HAYABUSA succeeded in rendezvousing with the target asteroid in September 2005. Index Terms--Deep space maneuver, ion engines, microwave discharge, plasma interactions.