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Galileo to be a crucial extension of global search and rescue

Ben Gilland
Mar 8, 2012, 8:00 UTC

Sen—Europe’s Galileo satellite navigation system will soon be adding its unique talents to a global search and rescue service.

The international satellite rescue system, Cospas-Sarsat, has been making air and sea travel safeter for 30 years and already saved 24,000 lives.

During a recent week-long meeting of the Cospas-Sarsat task group, representatives from 21 nations, including the European Commission and the European Space Agency (ESA), have been discussing the system’s future and finalising plans to incorporate the European Galileo satellite navigation system into the service over the next few years.

Founded by Canada, France, Russia and the US in 1979, Cospas-Sarsat (Cospas is a Russian acronym for “Space System for the Search of Vessels in Distress” and Sarsat stands for “Search and Rescue Satellite-Aided Tracking”) detects and locates emergency beacons activated by aircraft, ships and hikers in distress.

When it began, the Cospas-Sarsat system began with the LEOSTAR (Low Earth Orbit Search and Rescue) system of fast-moving, low-orbit satellites, which use “Doppler ranging” to pinpoint the location of distress calls.

But this system could only cover a small area of the globe at any one time, so valuable rescue time was lost before the satellites could be aligned with ground stations.

In response to this, in the 1990s Cospas-Sarsat incorporated coverage from high-altitude satellites in geostationary orbit.

Looking down from almost 36,000km, the GEOSTAR (Geostationary Earth Orbit Search and Rescue) system occupies a fixed location above the Earth, which allows them to receive and transmit distress calls immediately. But their relative lack of motion means that Doppler-based ranging isn’t possible.

The existing Cospas-Sarsat system uses satellites in low-Earth and geostationary orbits. Credit: ESA

Europe’s Galileo satellite will be used to fill the gap in the Cospas-Sarsat system by operating satellites that occupy a medium orbit.

The MEOSTAR (Medium Earth Orbit Search and Rescue) system will be able to combine the best elements of the previous two systems – providing global coverage and able to quickly identify the location of distress calls.

As an added bonus, the Galileo satellites will be able to send a “help is on the way” message to those in distress.

The first medium-orbit transponder of the Galileo system was launched last year and two more will be launched at the end of the summer.

Galileo is Europe’s answer to the American GPS, Russian GLOSNASS and Chinese Compass satellite navigation systems, which can be turned off during times of war – potentially leaving Europe without access to satellite navigation.

The £16 billion project, named after the Italian astronomer Galileo Galilei, will be a free service able to offer positioning measurements with a precision of one metre, which compares to 20 metres for the US and Russian systems.