Submillimeter observations from space: A space station submillimeter facility (SSSF)

There are many important scientific problems to be attacked in the submillimeter wavelength region including the astrophysics of star formation, the dynamics of protoplanetary systems, the physics of interstellar gas, mass loss from stars, supernovae, the chemical evolution of galaxies, the star formation rates in galaxies, the astrophysics of active galactic nuclei, the deuterium abundance in different astrophysical environments, and the distribution of the cosmic background radiation. However, to effectively explore this wavelength range requires going into space since atmospheric absorption precludes most observations from the ground. As in most areas of astronomy, the twin needs for sensitivity and high redsolution indicate use of an imaging interferometer, but the needed baselines of a few tens-of-meters require a large physical structure. The planned Space Station will provide, for the first time, a platform which is large enough to accommodate a forefront submillimeter synthesis instrument. Such a telescope would open an entirely new wavelength regime to astronomy with the attendant possibilities for unexpected new discoveries.A submillimeter array would also be technically well suited for operation on the Space Station. Second-of-are resolution at submillimeter wavelengths requires only relatively short baselines; pointing accuracy and tracking stability requirements are relatively crude being determined by the single dish size rather than the array resolution; radio frequency interference (RFI) susceptibility is very low due to the large frequency separation from normal communications bands; emissions from co-orbiting debris, dust, gas, and water vapour are uncorrelated between interferometer elements; baseline stability requirements, while severe, are less stringent than for optical/IR interferometers and can almost certainly be satisfied for existing phase correction and phaseless image restoration techniques; and the technology for the dishes, mounts, receivers, LO/IF systems, and correlators either exists or is a reasonable extrapolation of what already is available on the ground.We consider the applications and possible design of a Space Station based submillimeter array which could be mounted along the main (Y) axis of the Space Station and use orbital revolution and precession to produce high-resolution synthesis mapping in much the same way ground-based linear arrays do by Earth rotation synthesis.