A GALEX instrument overview and lessons learned

GALEX is a NASA Small Explorer mission that was launched in April 2003 and is now performing a survey of the sky in the far and near ultraviolet (FUV and NUV, 155 nm and 220 nm, respectively). The instrument comprises a 50 cm Ritchey-Chretien telescope with selectable imaging window or objective grism feeding a pair of photon-counting, microchannel-plate, delay-line readout detectors through a multilayer dichroic beamsplitter. The baseline mission is approximately 50% complete, with the instrument meeting its performance requirements for astrometry, photometry and resolution. Operating GALEX with a very small team has been a challenge, yet we have managed to resolve numerous satellite anomalies without loss of performance (only efficiency). Many of the most significant operations issues of our successful ongoing mission will be reported here along with lessons for future projects.