Abstract

We present an introduction to POINTS (Precision Optical INTerferometer in Space), a next-generation space-borne optical instrument and a leading candidate for the Astrometric Interferometry Mission recommended by the Bahcall committee. POINTS uses two starlight interferometers to measure the angle between two 10th magnitude stars (90° ± 3° apart) with 5 μarcsec precision (25 prad) in ~1 min. Analysis of many star pair measurements using measurement redundancy and 360° closure gives best-fit values for star positions and a full set of instrument biases. Each interferometer measures the angle between the starlight wave fronts and its baseline; internal laser metrology monitors the starlight path lengths and the angle between the two baselines. With instrument dimensions known to a few picometers, the star angle measurement can be nearly shot-noise limited; with stability over a few hours, the instrument can recalibrate its biases anew. Occasional measurements during a 10-year mission allow measurements of parallax to 0.4% at 10 kpc, a search for other planetary systems, calibration of the cosmic distance ladder, determination of 3-space positions and velocities, establishment of a stable reference grid, a possible second-order test of GR light deflection, and many other investigations.

© 1992 Optical Society of America