Demonstration of GPS on the alsat-1 disaster monitoring satellite

AlSAT-1, a 100 kg microsatellite launched in November 2002, is the first in a small constellation of satellites intended to monitor disasters around the world. The Disaster Monitoring Constellation (DMC) programme is led by Surrey Satellite Technology Ltd, UK, and comprises five or more small satellites in low Earth orbit providing daily imaging world-wide for the monitoring and mitigation of natural and man-made disasters and for dynamic Earth observation. The DMC satellites require GPS receivers to provide position, orbit and time information to support routine operations, and station housekeeping. As electrical power is a limited resource on the AlSAT satellite, it is necessary to operate the GPS receiver with a limited duty cycle to control the power consumption. This leads to a fairly harsh operating environment for the GPS receiver, as it must rapidly acquire and provide position and time fixes many times per day. Although the accuracy demands on the receiver are not too onerous, this demonstration gives an opportunity to test the receiver and exercise it in new ways, such that improvements can be made to its performance. This paper describes the operation of the SGR-10 GPS receiver on AlSAT-1, early performance measurements, a description of how the receiver is being used on the satellite, and lessons learnt, and upgrades planned for the future. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.