The Submillimeter Wave Astronomy Satellite is a groundbreaking mission designed to study the chemical composition of interstellar galactic clouds and the star formation process. SWAS is one of NASA's Small Explorer Missions and was air launched with a Pegasus XL rocket on December 5^th, 1998. SWAS is operated in collaboration with Harvard/Smithsonian Astrophysical Observatory, Cornell University, Johns Hopkins University, NASA Ames Research Center, and the University of Cologne. UMass scientists played a lead role in the radiometer design and development and are currently major contributors to the analysis of SWAS data.

SWAS's primary goal is to survey large areas of the sky in 5 submillimeter transitions of major astronomical importance: water (557 GHz), isotopic water (547 GHz), molecular oxygen (487 GHz), neutral carbon (492 GHz), and ¹³CO (551 GHz). These species were selected for observations because: (1) they should be sensitive probes of physical conditions in interstellar clouds; (2) they will provide important tests of chemical models of well-shielded (from UV radiation) regions in molecular clouds and of regions where photochemistry is important; and (3) water and CO are thought to be the most important coolants in molecular clouds and thus play an important role in determining the temperature of molecular clouds.