Monday, January 29, 2007

Hubble blows a fuse

Some rough news out of NASA today. This is a memo straight out of Space Telescope Science Institute, so pardon the jargon. The ACS is the Advanced Camera for Surveys, which has been the main camera used on the telescope since it was installed in spring of 2002. There are a battery of instruments on the telescope which can pick up the slack, but the other imaging camera, WFPC2, is considerably older technology, with lower throughput and sensitivity.
Unfortunately, it is clear that there has been a serious failure in side 2 of the ACS. Indications are that there was an electrical short circuit of sufficient duration and intensity to blow the fuse on side 2. An Anomaly Review Board will attempt to identify the precise cause of the problem, but it is very unlikely that we will be able to use ACS side 2 again. The ARB will have to establish whether it is safe to return ACS to side 1 operation. If so, we will be able to use the SBC, but not the HRC or WFC. The ARB will also help establish whether there is any prospect for servicing the ACS. While the blown fuse can easily be replaced by an astronaut, repairing or working around the short circuit could be considerably more difficult. ...

The apparent loss of the ACS is obviously a serious blow to the HST science program. ACS observations have dominated our observing schedules since its installation during SM3B. We now have the problem of replacing the ACS portion of the observing program and continuing with the best possible science program with the telescope, at least until SM4. Several steps are being taken in this regard. First, the schedulers will be doing the best they can to move up available Cycle 15 NICMOS, WFPC2, and FGS observations. Second, we will activate the ACS Contingency programs that have been proposed and selected for just this situation. ...
Hopefully, the planned servicing mission will still go forward. Though currently planned for mid-2008, there was some talk about whether this could be bumped up. It is still too early to tell at this point, but my initial guess is maybe, but not by much. That mission has plans for an even newer camera and the usual service pack of gyros and batteries.


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