ISSTT Proceedings

ISSTT Proceedings

You searched for:search icon

No Keywords
Showing 0 of items from your search. Start over 

Submillimeter Wave Astronomy Satellite

Authors:
Paul F. Goldsmith
Abstract:
The Submillimeter Wave Astronomy Satellite (SVVAS) was selected in 1989 by NASA, for a scheduled Scout launch in 1993. The objectives of this mission within the Small Explorer Program are to study dense clouds in the interstellar medium via critically important transitions of molecular and atomic species which can be observed only at submillimeter wavelengths. SWAS will thus observe transitions of water vapor at 557 GHz, molecular oxygen at 487 GHz, atomic carbon at 492 GHz, and carbon-13 monoxide at 554 GHz. These frequencies are totally or largely opaque from the ground, and a space—based survey of molecular clouds throughout our galaxy will yield important new information about the chemistry in very dense clouds in the Milky Way, and the process of star formation. The SWAS instrument employs a 55—cm diameter offset Cassegrain antenna with a nutating secondary reflector. The receivers are second harmonic downconverters, using Schottky diodes as the mixing elements, with phase locked InP Gunn devices as the local oscillator sources. The receiver front ends are passively cooled to [approx.] 150 K. Spectral analysis is performed by an acousto—optical spectrometer with 1.4 GHz bandwidth, which covers the four lines simultaneously. SWAS represents the first space—borne system operating in the submillimeter range, and as such is providing considerable impetus for development of highly reliable, compact, components which have low mass and power consumption. We see SWAS as the precursor of more elaborate submillimeter astronomy missions, and complementing work done from airborne platforms and dry sites on the Earth's surface.
Categories:
Applications
Year:
1990
Session:
5
Full-text:
Download a PDF of this paper.
Page Number(s):
458-477