The Mons Star Trackers

There is clear scientific interest in using the photometry from a star tracker to observe variable stars. Despite the small aperture, the advantages of space (long observing periods and no atmospheric scintillation) make such a camera superior to ground-based telescopes for some applications. The only example so far has been the work by Buzasi et al. (2000 and these Proceedings), who are making impressive use of the 52-mm star camera on the WIRE satellite after the failure of the main instrument. As far as we know, MONS is the first mission to be designed from the start to use star trackers for science. Of course, we must keep in mind that the primary role of the star trackers is to sense spacecraft attitude with the precision required for the main camera.