Submillimeter-wave astronomy satellite

The submillimeter wavelength range (100 micrometers <EQ (lambda) <EQ 1 mm) is exceptionally rich in atomic and molecular transitions that provide direct measures of the chemical composition, temperature, density, and cooling of the interstellar medium. In part, this is due to the fact that the most abundant oxygen- and carbon-bearing species as well as the most common hydrides have their lowest lying transitions within this wavelength region. However, because of the great abundance of many of these same species in our own atmosphere (e.g., H(subscript 2)O and O(subscript 2)), terrestrial absorption at submillimeter wavelengths is strong, rendering much of the sky inaccessible to ground- and even airborne observing platforms. In recognition of the scientific importance of the submillimeter range to astronomy and the limitations placed on its pursuit by the atmosphere, both NASA and ESA have embarked on ambitious programs to explore these wavelengths from space. The Submillimeter Wave Astronomy Satellite (SWAS), part of NASA's Small Explorer Program, is the first of these endeavors. During its planned 3-year lifetime, SWAS will survey dense ((eta) (subscript H(2)) > 10(superscript 3) cm(superscript -3)) molecular clouds and cloud cores within our galaxy in five astrophysically important transitions of H(subscript 2)O, H(subscript 2) (superscript 18)O, O(subscript 2), CI, and (superscript 13)CO. SWAS is scheduled for launch in 1995.