The Submillimeter Wave Astronomy Satellite (SWAS) is a NASA submillimeter astronomy satellite, and is the third spacecraft in the Small Explorer program. It was launched on December 6, 1998 (UTC), from Vandenberg Air Force Base aboard a Pegasus XL rocket. The telescope was designed by the Smithsonian Astrophysical Observatory and integrated by Ball Aerospace, while the spacecraft was built by NASA's Goddard Space Flight Center. The mission's principal investigator is Gary J. Melnick.