<title>ASTRO 1M: a new system for attitude determination in space</title>

Abstract

ASTRO type systems for autonomous attitude determination in space are introduced. They recognize stars which are registered in the field of view (FOV) of a star sensor by using an on-board star catalogue for subsequent attitude determination in the 2nd equatorial coordinate system. The star sensor utilizes a Peltier cooled CCD array in the focal plane of a 1.4/100mm lens which realized a FOV of 5.3° * 8°. A first microprocessor system reduces the CCD readout data to the images of the registered stars and subsequently computes the exact star positions. A second microprocessor system realizes the attitude determination and is able to handle up to three star sensors simultanously. Utilizing more than one star sensor in a nearly orthogonal configuration allows a 3-axes attitude determination with a high accuracy.The first ASTRO type system -the ASTRO 1 -was designed and manufactured from 1984 to 1987 and launched in November 1989 on Module D to the Soviet MIR space station. Test results demonstrate that the in-orbit performance is better than specified. The star sensor registered stars up to 8.Om, and the measurement accuracy for attitude determination is characterized by 1 -2 arcsec.