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T.G. Phillips (Caltech)
The Herschel Mission is a European Space Agency (ESA) cornerstone project consisting of a 3.7 m diameter passively cooled telescope and liquid helium cooled focal plane, to be placed into an L2 orbit. NASA is an important collaborator providing many of the instrument components. Herschel will be launched by an Arianne V rocket in 2007. The mission lifetime will be at least 3 years. The telescope will be diffraction limited to about 100 microns. The three instruments are PACS, using a mixture of photodetectors and bolometers for moderate resolution grating spectroscopy and continuum mapping, SPIRE, using bolometers and an FTS for moderate resolution spectroscopy and continuum mapping at longer wavelengths, and HIFI, a heterodyne instrument covering about 500 GHz to 2000 GHz (with one or two gaps in coverage) at very high resolution. HIFI uses a combination of SIS and HEB detectors and a novel diode multiplyer scheme for the local oscillator. All three instruments have requirements for laboratory work, but HIFI is the most in need and will be emphasized here.
HIFI is designed for study of lines impeded by the Earth’s atmosphere. These are primarily water lines, so a major requirement for HIFI is the collision parameter for \mathrm{H2O}, for levels up to J=6, at least. Line frequencies are essential for HIFI, particularly for hydride and deuteride molecules, where there may be only one or two lines available to Herschel and identification will depend on accuracy in both the lab and the ISM.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.