POINTS: an astrometric spacecraft with multifarious applications

POINTS is a dual astrometric optical interferometer with nominal baseline length of 2 m and measurement accuracy of 5 microarcsecs for targets separated by about 90 degrees on the sky. If selected as the ASEPS-1 mission, it could perform a definite search for extra-solar planetary systems, either finding and characterizing a large number of them or showing that they are far less numerous than now believed. If selected as AIM, it could be a powerful new multidisciplinary research tool, opening new areas of astrophysical research and changing the nature of the questions being asked in some old areas. Based on a preliminary indication of the observational needs of the two missions, we find that a single POINTS mission lasting ten years would meet the science objectives of both ASEPS-1 and AIM. POINTS, which is small, agile, and mechanically simple, would be the first of a new class of powerful instruments in space and would prove the technology for the larger members of the class that are expected to follow. The instrument is designed around a metrology system that measures both the critical distances internal to the starlight interferometers and the angle between them. Rapid measurement leads to closure on the sky and the ability to detect and correct time-dependent measurement biases.