FUSE

Explorer 77, Far Ultraviolet Spectroscopic Explorer, MIDEX-0

Mission Profile

FUSE (Far Ultraviolet Spectroscopic Explorer, Explorer 77) was a NASA ultraviolet astronomy satellite launched on 24 June 1999 aboard a Delta II to study the far-ultraviolet universe at wavelengths between 905 and 1195 angstroms. Its primary mission was to observe deuterium in the interstellar medium, providing constraints on Big Bang nucleosynthesis models and the chemical evolution of the universe. FUSE also studied stellar atmospheres, interstellar gas, and the intergalactic medium with unprecedented spectral resolution. The mission operated for nine years before losing its final reaction wheel in 2007, ending operations after a remarkably productive career.