A machine used for attitude control, such as a flywheel.

Hayabusa-san's RWs are installed to cover the three dimensional directions of x-axis, y-axis, and z-axis. However, the RW for x-axis suddenly stopped functioning.

The failure rate of an operating machine is higher than that of a non-operating machine. Since there is no repair shop in Space, we can do nothing to fix it once the machine breaks down.

Thus, JAXA/ISAS considered that the RW, which would constantly keep rotating, needed further attention to care.

The failure of one axis was actually the circumstance within range of expectations.

The immediate measure was taken, and there was no significant effect on the mission.

However, the decreased accuracy in attitude control more or less affected the fine observation.

The failure rate of an operating machine is higher than that of a non-operating machine. Since there is no repair shop in Space, we can do nothing to fix it once the machine breaks down.

Thus, JAXA/ISAS considered that the RW, which would constantly keep rotating, needed further attention to care.

The failure of one axis was actually the circumstance within range of expectations.

The immediate measure was taken, and there was no significant effect on the mission.

However, the decreased accuracy in attitude control more or less affected the fine observation.