FUSE Mission Status Report

Mission Status Report #26      Star Date: December 6, 1999

NOTE: Mission Status Reports on the web page will continue roughly once a week.

-- Bill Blair

A graphic view of the FUSE on orbit (left) and one of the four FUSE Mirrors (right).

(Click either image to see larger version.)

FUSE Increases Science Production

FUSE operations have continued smoothly over the last week, concentrating on requested science observations. The FUSE satellite obtained over 160,000 seconds of data on 13 different science targets last week, our second best week since launch. Hence, new scientific data are pouring in even as we continue some final checkout activities. Over 50 targets have been observed for science purposes now, including the first observations for programs by Guest Investigators.

Prior to that, we have just come through several weeks of intensive tests to help us characterize and then learn how to manage the channel alignments of the four FUSE mirrors. (You may recall from earlier reports that thermal effects affect the mirror alignments.) This process has gone well, and the data obtained have allowed us to understand how the mirrors move as FUSE points from one part of the sky to another. We have also been experimenting with ways of controlling these tiny motions to keep the mirrors aligned at an approximate level. This has included practice using a "peak-up" technique to realign the channels when they are close but not fully aligned. The result has been that over the last week or so, about 3/4 of the observations have included data in at least three channels, and 60% has included data in all four channels! And we are still learning! These are very positive steps.

An interesting note: the operations team here is as interested in getting into a "normal operations" mode as much as anyone. Planning and scheduling these "special" checkout programs is a grueling exercise for the whole team. Planning science observations is easier, but still has some difficulties as we work new planning constraints into our ground system software. Pursuing on-going operations and system upgrades simultaneously is difficult, but it is a job we must do to make operations smoother down the road.

Reported by: Bill Blair, Chief of Mission Planning

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