Sure satellites can transmit radio and television signals, but can they save lives too? Of course they can! Search and rescue satellites are designed to provide a way for vessels at sea and in the air to communicate from remote areas. These satellites can detect and locate emergency beacons carried by ships, aircrafts, or individuals in remote or dangerous places.
The first rescue aided by spacecraft was in September of 1982 when a Soviet satellite, Cosmos-1383, detected a distress beacon from a pair of small airplanes that had crashed. The satellite was able to give rescuers the location of the two downed planes; they were the airplanes of a young man and the young man's father who had set out looking for his son's plane crash site.
The idea of search and rescue satellites comes from weather satellite programmes. Meteosat, for example, monitors weather patterns by direct observation, but it also analyzes signals sent out from buoys floating in the ocean. Those buoys collect local weather information and transmit that to the satellite. The satellite then uses the doppler effect to find out where that particular buoy is. This mechanism is similar to the technology now used for search and rescue.
Satellites equipped with search and rescue equipment fly over a beacon that is releasing an emergency signal. Using mathematical calculations involving the doppler effect, scientists can translate that signal into coordinates, and determine the location of the distress signal within four kilometres.
In 1974, Canada made it law that all aircraft must carry a beacon called an Emergency Locator Transmitter (ELT). After the ELT came the Emergency Position Indicating Radio Beacon (EPIRB). EPIRB's are automatic, self-powered, very portable, completely waterproof, and they float.
The newest search and rescue system is the Cospas-Sarsat system. It is an international search and rescue system made up of a network of satellites in space, and control centres on Earth-ground stations, mission control centres, and rescue coordination centres. The Sarsat system was developed in a joint effort by the United States, Canada, and France. The Cospas system was developed by the Soviet Union. These four nations banded together in 1979 to form Cospas-Sarsat. In 1982, the first Cospas-Sarsat satellite was launched, and by 1984 the system was declared fully operational. From there, the Cospas-Sarsat organization continued to grow. The four original member nations have now been joined by 25 other nations that operate 28 ground stations and 15 mission control centres worldwide. In the eyes of the countries using this system, Cospas-Sarsat has very much helped search and rescue efforts.
To find out how the Cospas-Sarsat search and rescue system works, click here.