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Mission Status Report #107      Star Date: June 14, 2007

FUSE Returns to Science Operations!

Caption: The FUSE satellite is seen superimposed on an optical image of the nearby galaxy known as the Large Magellanic Cloud, a satellite galaxy of the Milky Way. At a distance of only 170,000 light years, the Large Magellanic Cloud is of intense in this galaxy have been observed to date, with many other stars still awaiting their turn in the FUSE limelight. (Graphic courtesy NASA and Lauren Fowler, the JHU FUSE project.)

(Click image above to see larger version.)

I am delighted to report that we have returned FUSE to science operations, just slightly over one month after an anomaly involving the skew reaction wheel. (See the

On Tuesday evening, June 12, 2007, we performed a nominal recovery slew to a position near the south orbit pole. The science timeline was rejoined, the detector high voltages were brought up to nominal levels, and observing resumed. Our preliminary assessment of the early science data, from comparing a new observation of a previously observed target to existing data, shows no significant degradation of the science data quality due to the hiatus in operations. This is truly good news!

Analysis of the telemetry over the past several weeks has shown the performance of the wheel is essentially back to pre-anomaly performance levels. Whatever the cause of the initial wheel anomaly, it has apparently cleared itself as we have run the wheel at moderately high speed for the last few weeks. As a conservative measure, we are currently operating with the wheel spinning in one direction and avoiding low wheel speeds and "zero crossings." Timelines have been prepared for the coming weeks, and it appears that this is not a difficult requirement for generating science timelines. As we gain experience, we are likely to relax this self-imposed requirement to provide as much flexibility as possible for doing the best science.

I want to express my continued thanks to (and admiration of) the many people who have put in long hours to bring FUSE back into nominal operations. Many people sacrificed sleep, weekends, and put forth exceptional effort to make this possible. My hat is off to you all!

Reported by: Bill Blair, FUSE Chief of Observatory Operations

Last Update: June 14, 2007

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