Hayabusa Finished First Leg of Orbit Maneuver toward Earth

Hayabusa asteroid explorer had been executing the powered flight toward Earth using a single reaction wheel and the microwave discharge ion engines since April this year. The achievement of the first leg of orbit maneuver around the perihelion led Hayabusa into turning off them and shifting the spin mode from three-axis attitude stabilization on October 24, 2007 according to the plan. The ion engines generated 1,700 m/s delta-V with 31,000 hours in total accumulated operational time up to now and still keep good thrust performance and enough propellant.
Hayabusa will fly in ballistic manner with the spin axis tracking toward Sun by the solar pressure torque without any propellant consumption. And it will resume the orbit maneuver in the second leg from February 2009 aiming for Earth return on June 2010. The remaining delta-V toward Earth is only 400m/s.

Hitoshi Kuninaka

October 29, 2007