Workers prepare to attach the Pegasus XL and Galaxy Evolution Explorer GALEX satellite to the Orbital Sciences L-1011 aircraft.

At Cape Canaveral Air Force Station, workers prepare to attach the mated Pegasus XL and Galaxy Evolution Explorer (GALEX) satellite to the Orbital Sciences L-1011 aircraft. The GALEX, to be launched April 28 from the L-1011, will carry into space an orbiting telescope that will observe a million galaxies across 10 billion years of cosmic history to help astronomers determine when the stars and elements we see today had their origins. The spacecraft will sweep the skies for 28 months using state-of-the-art ultraviolet detectors to single out galaxies dominated by young, hot, short-lived stars that give off a great deal of energy at that wavelength. These galaxies are actively creating stars, and therefore provide a window into the history and causes of star formation in galaxies.