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Mission Status Report #88      Star Date: June 27, 2005

FUSE Celebrates Six Years in Orbit!

Caption: The FUSE satellite aboard its Delta-II rocket disappears into the hazy blue sky above Cape Canaveral Florida on June 24, 1999. (Photo courtesy NASA and the FUSE project.)

(Click image above to see larger version.)

Friday June 24th marked the sixth anniversary of the launch of FUSE aboard a Delta-II rocket into the roughly 500 mile (800 km) orbit above the earth. Since that time FUSE has orbited the earth every 100 minutes, totalling some 31,560 orbits and some 840 million miles (1.3 billion km) travelled. From that vantage point, FUSE has been used to observe over 2300 unique science targets for nearly 52 million seconds of science observing time, quite a remarkable achievement.

And we're not done yet!

It was six months ago today that a hardware failure knocked us off-line for science operations. (See this earlier Status Report or others from this series.) However, we continue to make steady progress toward the return to science operations over the last few weeks, using a revised attitude control software system with existing functional hardware to replace the missing failed reaction wheels. We have spent most of the time since my last report in a test mode whereby we plan observations with our revised scheduling tools and then compare to actual performance to validate the tools. It is a laborious process, but one that is necessary for us to get back into a realistic science scheduling mode. Overall, these tests are progressing well.

Even as we are operating and "learning as we go" with the software that is onboard, continued improvements to the control software are being made and tested on the ground. This is likely to be an ongoing process for some time to come, as we tweak the system to make it perform better. Controlling FUSE pointing has gotten very complicated, but with the right combination of control parameters, we expect to be able to improve performance considerably above what we can currently do.

Continued thanks to all of the FUSE Sciences Operations team, including our partners on the Mission Operations Team from Honeywell Technology Solutions, Inc., and our colleagues at Orbital Sciences Corporation, for their tremendous effort so far, and for their ongoing efforts as we improve the new control system.

Reported by: Bill Blair, FUSE Chief of Observatory Operations

Last Update: June 27, 2005

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