The Extreme Ultraviolet Explorer mission

The Extreme Ultraviolet Explorer mission is described. The satellite is now scheduled to be launched in September, 1991. For the first six months, an all sky survey will be carried out covering 90 to 820 A, or essentially the entire EUV bandpass. This EUV survey will be made in four bands, or colors, 90-150 A; 170-250 A, 400-600 A, and 550-750 A. A portion of the sky which is free from the normally intense 304 A geocoronal helium background will be surveyed at greater sensitivity. Following the sky survey portion of the mission, spectroscopy of individual sources will be carried out. Three spectrometers employing novel variable line spaced gratings will provide spectra with about 1 A resolution over the band from 90 to 800 A.