The Far Ultraviolet Spectroscopic Explorer (FUSE) is an astrophysics satellite currently being designed to provide high spectral resolving power ((lambda) /(Delta) (lambda) approximately equals 30,000) observations in the interval 853 - 1248 angstrom. It consists of four co-aligned normal incidence mirrors which illuminate high density, holographically ruled diffraction gratings on spherical substrates. High resolution spectra are formed on a pair of microchannel plate detectors with KBr photocathodes and delay line anodes. A separate low dispersion channel ((lambda) /(Delta) (lambda) on the order of magnitude 500) permits observations in the extended wavelength interval 800 - 1600 angstrom with long slit spatial imaging better than 5 arcseconds. The utility of observing in the prime FUSE spectral region is due to the vastly greater number of important transitions of atoms and ions in the ultraviolet compared to the visible. This makes FUSE a powerful instrument for measuring physical parameters such as temperature, pressure, density, and abundance in a wide variety of astrophysical sites. Among the many problems FUSE will address are the deuterium abundance in the universe; the character and distribution of the components of the hot interstellar medium such as O VI which must be understood to model galactic evolution; and physical processes in the atmospheres of planets and planetary systems.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.