SWAS (Submillimeter Wave Astronomy Satellite) is part of NASA's Small Explorer (SMEX) program. The SWAS instrument is a submillimeter wave telescope launched on December 2, 1998 and operated in a 600 km circular orbit with 70 degree inclination. Scientific objectives of SWAS are to study the chemical composition, energy balance and structure of interstellar clouds, both galactic and extragalactic, and the processes that lead to the formation of stars and planets.