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Session 71 - Space Astronomy in the Next Millennium.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[71.04] POINTS: a small low-cost spaceborne astrometric optical interferometer

R. D. Reasenberg, R. W. Babcock, M. A. Murison, M. C. Noecker, J. D. Phillips (SAO/CfA), B. L. Schumaker, J. S. Ulvestad (JPL), W. McKinley, R. J. Zielinski (Itek Optical Systems), C. F. Lillie (TRW)

POINTS (Precision Optical INTerferometer in Space) would perform microarcsecond optical astrometry from space. In a five-year mission, POINTS could yield, e.g., a 1% Cepheid distance scale, galactic mass distribution, knowledge of cluster dynamics, and stellar masses and luminosities. POINTS could also perform a deep search for other planetary systems. The search would have a reliable detection threshold that would reach Earth-like planets for a few of the stars and be less than an order higher for over 1000 stars. The detection of longer period planets would benefit from a ten-year mission. POINTS does global astrometry, i.e., it measures widely separated targets, which yields closure calibration, numerous bright reference stars, and absolute parallax.

POINTS comprises a pair of independent Michelson stellar interferometers and a laser metrology system that measures both the critical starlight paths and the angle between the two baselines. The nominal design has baselines of 2 m, subapertures of 35 cm, and targets separated by 87 to 93 deg. Simplicity, stability, and the mitigation of systematic error are the central design themes. The instrument has only three moving-part mechanisms, and only one of these must move with sub-milliradian accuracy. On each side of the interferometer, there are only three (interferometrically critical) optical surfaces preceding the beamsplitter or its fold flat. POINTS is small, agile, and mechanically simple. It would prove much of the technology for future spaceborne interferometers.

The development of POINTS has been supported by the Smithsonian Institution, NASA, JPL, Itek, and TRW.

^Present address: USNO, Washington, DC ^\ddagPresent address: Ball Aerospace amp; Technologies Corp., Boulder, CO

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