Submillimeter Wave Astronomy Satellite

The Submillimeter Wave Astronomy Satellite (SWAS) was a NASA SmallExplorer Program (SMEX) mission that launched on December 5, 1998 and made initial observations until July 21, 2004 followed by a 3 month re-activation period in June 2005 (after a year of stand-by operation) to observe the effects of the Deep Impact probe's collision with Comet P/Tempel 1. SWAS measured the amount of water and molecular oxygen in interstellar clouds, and also the amounts of carbon monoxide and atomic carbon, which are believed to be major reservoirs of carbon in these clouds.

Its overall goal has been to gain a greater understanding of star formation by determining the composition of interstellar clouds and establishing the means by which these clouds cool as they collapse to form stars and planets. SWAS focused on the following spectral lines: Water (H2O) at 556.936 GHz, Molecular oxygen (O2) at 487.249 GHz, Neutral carbon (CI) at 492.161 GHz, Isotopic carbon monoxide (13CO) at 550.927 GHz, and Isotopic water (H218O) at 548.676 GHz.