FUSE Mission Status Report

Mission Status Report #59      Star Date: June 24, 2002

FUSE--Three Years On Orbit!!

Caption: (Left) FUSE Launch, June 24, 1999. (Right) Artist's concept of FUSE on orbit. (Graphic provided by the Canadian Space Agency. See

All continues to go well on the FUSE project as the satellite passes the three year anniversary of launch, June 24, 1999. We are more than 2/3rds of the way through the primary science mission, even as we have been planning for an expected period of extended operations beyond March 2003. FUSE has orbitted earth more than 15,300 times, and has observed over 1600 celestial objects for a total of more than 22 million seconds.

The FUSE satellite continues to operate well after our recovery from Reaction Wheel problems, we are also busy preparing revised flight software to address a potential future problem that may occur with our gyroscopes. These devices have limited (but unknown) lifetime, and could become a stumbling block to operations. Instead of waiting for the problem to occur, we are being proactive in developing a flight software system that will permit operations with a reduced number of gyros in the control loop, all the way down to "no gyros" if necessary. Hence, this development effort is referred to as "gyroless mode," even though it should be a long time until we have no gyros in the system. A milestone was reached in mid-June, with a Critical Design Review meeting for this new way of doing business. The review, held at JHU, went soothly, and we expect to new system to be put into place during October 2002.

On another front, the semi-annual American Astronomical Society meeting was held the first week of June in Albuquerque, NM. Over 25 FUSE presentations were made, including a five-talk seesion on Monday by FUSE Operations personnel, reporting on the recovery of operations with FUSE and informing users of the new constraints we have to work under now.

We are working hard to prepare for the call for the 4th round of guest investigator proposals with FUSE. The release of the NASA Research Announcement for this opportunity is expected in July 2002, and proposals will be due in early to mid-October. Here's hoping for at least several more solid years of science from the FUSE satellite!

Reported by: Bill Blair, Chief of Observatory Operations

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