NASA has once again rescued its Far Ultraviolet Spectroscopic Explorer research satellite, following yet another reaction wheel failure. It is now running on one out of the original four.
“It’s really a level of performance that we never thought we would see again,” said Professor William Blair, FUSE’s chief of observatory operations. “The old satellite still has some spunk.”
Reaction wheels are used to point the satellite and are where unwanted rotational energy is dumped. Without them the satellite eventually starts to rotate.
The revised control mode was originally developed in 2001 when the first two wheels failed and treats the whole satellite like a compass needle by borrowing the satellite’s magnetic torquer bars which can interact with the Earth’s magnetic field.
“The FUSE control system has been modified again to use magnetic control on two axes, which provides a tenuous but acceptable level of control in place of the missing reaction wheels,” said NASA.
fuse.pha.jhu.edu/