Hello World,

The FUSE satellite is back on-line in data gathering mode after spending 4-1/2 days troubleshooting a problem with one of the spacecraft's "reaction wheels." There are four such devices on FUSE, and normally all four wheels are used in the control loop to point FUSE from place to place in the sky and to hold it steady in position while observing. For normal operations at least three of the four wheels must be operating.

On February 16, 2001, one of the reaction wheels drew excessive current and took itself out of the control loop automatically. (See Mission Status Report #42.) After a brief time, we were back on-line performing science, controlling in three-wheel mode. However, on Friday, February 23, 2001, we took time off from science observations to troubleshoot the problem wheel and try to bring it back into service, providing the satellite with important redundacy in case of any future problems.

This activity has been completed. All four wheels are operating in the control loop and we are back on the science timeline.

Reported by: Bill Blair, Chief of Observatory Operations