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The Submillimeter Frontier: A Space Science Imperative

A major goal of modern astrophysics is to understand the processes by which the universe evolved from its initial simplicity, as seen in measurements of the Cosmic Microwave Background, to the universe we see today, with complexity on all scales. While the diffuse background measurements of COBE reveal the importance of the far infrared and submillimeter in early galaxy and star formation, the understanding of the development of complex structure requires high resolution imaging and spectroscopy. We present a concept for a space mission called SPECS, the Submillimeter Probe of the Evolution of Cosmic Structure, which provides these capabilities. SPECS is a cold, spatial and spectral Michelson interferometer with adjustable baselines ranging up to 1 km. It has Hubble sensitivity and angular resolution in the far IR and submillimeter, spectral resolution up to 10,000, and a 14' field of view. SPECS will be able to image thermal dust continuum and infrared cooling and diagnostic line emission over a wide range of redshifts, providing extinction-free astrophysical probes of young galaxies and early cosmic structures, and measures of the luminosity and heavy element formation history of the universe. SPECS would also have the potential to improve vastly our knowledge of protostars, protoplanetary systems, Active Galactic Nuclei and other objects in the local universe. We recommend that a concerted effort be made during the next decade to develop and test certain critical technologies (photon-counting far IR detectors, formation flying spacecraft, cold, lightweight mirrors, and active coolers), so that SPECS can be deployed in about 2015.