The Far Ultraviolet Spectroscopic Explorer (FUSE) is studying a wide range of astronomical problems in the 90.5–118.7-nanometer wavelength region through the use of high-resolution spectroscopy. The FUSE bandpass forms a nearly optimal complement to the spectral coverage provided by the Hubble Space Telescope, which extends down to about 117 nm. The photoionization threshold of atomic hydrogen (91.1 nm) sets a natural short-wavelength limit for the far ultraviolet. FUSE was launched in June 1999 from Cape Canaveral, Florida, on a Delta II rocket into a 768-km (477-mi) circular orbit. Scientific observations started later that year.