SARSAT
by Roy McPherson
The Search and Rescue Satellite Tracking (SARSAT) Project was an international effort to demonstrate the use of satellites to locate aircraft and ships in distress, faster and with greater accuracy than by current conventional means.
DND first considered the potential for a satellite-aided tracking system in 1972. It asked DOC and private industry to study the use of polar-orbiting satellites to improve detection of distress signals from both land and sea locations. The OSCAR program, carried out by the DOC/CRC in the mid-'70s, demonstrated the system's technical feasibility.
By 1978 considerable interest had been shown by Canada, the USA and France in supporting an international demonstration of the system concept. That same year, CRAD sponsored Canada's SARSAT Project and assigned it to DREO. DREO established a project team of Rod Hafer (thc Project Manager), Harvey Werstiuk (DOC/CRC), the Technical Manager, and Roy McPherson, Deputy Project Manager and System Evaluation Manager. The following year Treasury Board approved the Canadian project and later, in the same year, signed an international Memorandum of Understanding. The other SARSAT parties were France and the USA. In parallel, another MOU was agreed to between the SARSAT Project and the Soviet Union, representing the equivalent Soviet Project (COSPAS).
The technical basis of the system is as follows: Emergency Locator Transmitters (ELTs) introduced to the North American civil aviation community in the early 1970s, ensure rapid notification of a distress situation and provide a homing ability. The marine equivalent is the Emergency Position Indicating Radio Beacon (EPIRB). Working with existing ELTs and EPIRB5 the satellite acts as a simple repeater. It receives the ELT transmission and re-modulates it onto a down-link signal carrier. On the ground, the signal is received at a Local User Terminal (LUT). Here the uplink Doppler shift is measured as thc satellite passes thc ELT. This information, plus accurate knowledge of the satellite orbit, allows the calculation of the latitude and longitude of the ELT location. This calculated location then is relayed via the Mission Control Centre (MCC) to an appropriate Search and Rescue authority for action.
Canadian industry contributed significantly to the Canadian portion of thc system's hardware. SPAR Aerospace of Montreal built the repeaters that Canada provided for integration on the American satellites. Canadian Astronautics Ltd. of Ottawa built the LUT that was installed at DREO. They also provided LUTs to the U.S. SED Systems Ltd. of Saskatoon designed and built the MCC that the project installed at CFB Trenton adjacent to the Trenton Rescue Coordination Centre (RCC).
The technical verification of the joint COSPAS/SARSAT system began with the launch of the first spacecraft, COSPAS-I, by the Soviet Union in June 1982. This was followed by the launch of the second Soviet satellite, COSPAS-II, and the first SARSAT satellite, SARSAT-I (NOAA-8), in March 1983. A series of technical system performance tests were then completed to confirm proper functioning of the system. A Demonstration & Evaluation phase began in February 1983, with the active participation of user services. COSPAS-III was launched in June 1984 followed by SARSAT-II (NOAA-9) in December 1984. The Demonstration and Evaluation was completed in mid 1985.
In its earliest days in space, and while still in its R&D phase on 9 September 1982 (less than 3 months after COSPAS-I was launched), a small aircraft crashed in a remote mountain valley in Northwestern B.C. The plane was 90 kilometres off its planned route and rescuers faced days of frustrating searching of many square miles of extremely rugged terrain before they would have found the crash site. Instead, COSPAS-I detected the ELT transmission and relayed it to the LUT at DREO. After processing, the location data was sent to the MCC at CFB Trenton which passed the information to the local RCC for action. Within hours, the survivors were being airlifted out from the crash site to safety, demonstrating the practicality of the system. Stories of this nature were to be repeated over and over. By the close of the evaluation in 1985, the system had provided alerting-and-location data for some 194 distress incidents world-wide, involving 529 people, of whom nearly 500 were rescued.
DREO completed its role in the project in 1985 with the establishment of an Interim Operational System, managed by the CEM Branch. Its task was to give full Canadian ground coverage from installed and upgraded LUTs in Edmonton, Churchill and Goose Bay. The MCC facility at CFB Trenton also was upgraded to operational standards and approval was given for Canada to provide instrumentation for additional satellites.
In the summer of l99l the DREO effort came to fruition: the Canadian SARSAT system was declared fully operational and passed into the realm of the day-to-day operational technology of search and rescue.
Source: The 50th Anniversary Edition of the History for Defence Research Establishment Ottawa, compiles and edited by Jim Norman and Rita Crow, 1991.
