Hayabusa update: Now three of four engines are working!
When I last heard about Hayabusa, things seemed pretty grim; only one of four ion engines was working, only one of three reaction wheels functioning, and chemical fuel was exhausted. But the Japanese engineers in charge of the salvage of the return part of the Hayabusa mission continue to display creativity and dedication, and according to an update on JAXA's website, they have managed to restore two more of the engines to functional status.
The engines are referred to by letters A through D. A has not been in use for some time. B has been in intermittent use; it is D that has provided most of the spacecraft's return thrust, and that one is now up to 13,500 hours of use (all the engines were supposed to have a design lifetime of 14,000 hours). The update states that engine C, which was performing unstably in the past, was restored to stable function at the end of July. Now, to preserve engine D, they are primarily using the newly restored engine C.
The update ends with the following: "Hayabusa will continue the powered flight using the engine C till November this year and then change to the ballistic flight with hibernation mode.