GPS rival to integrate tech for global search and rescue system

Representatives of the Galileo project, Europe's effort to establish a civil global positioning system, have presented an ambitious plan to equip its satellites with a future worldwide search and rescue technology to be able to locate and communicate with individuals in emergency situations anywhere on the globe.

The new project was announced as part of the recent annual Joint Committee Meeting of COSPAS-SARSAT, an international initiative focused on a satellite system for search and rescue. Galileo representatives confirmed that their future satellite system will be equipped with transponders to relay distress signals to search and rescue organizations, as a key technology of MEOSAR (Medium Earth Orbit Search And Rescue), a future worldwide search and rescue satellite system.

What is fascinating about the Galileo system is that it promises to overcome many of the limitations satellite-based rescue systems have today.

COSPAS-SARSAT currently operates a total 12 satellites. Five "Geosar" geostationary satellites orbit in 1000 km altitude: These satellites remain fixed relative to the position of the Earth and have a relatively poor coverage of the polar regions. This deficiency is somewhat covered by seven low-Earth orbit (850 km altitude) "Leosar" satellites circling the Earth around the poles. The major downside of today's system, which went into operation almost 25 years ago on September 10, 1982, is that there can be a substantial delay in relaying distress signals, which currently can be received through beacons at 121.5 MHz and 406 MHz.

The system cannot monitor the complete surface of the Earth at any given moment and depends on a satellite passing a distress signal overhead. In addition, the satellites cannot relay a distress signal to the ground at any given time, but rather have to store the location of the emergency and send it to a base station once there is one in reach. COSPAS-SARSAT says that it can take up to one hour until a signal is received and sent back to the ground.

Also, distress signals need to have a direct line of sight to the satellites, which may not be possible in some situations, especially in accident situations where individuals are trapped in a deep valley and the surrounding terrain obscures the view to the satellite.

Galileo promises to solve these problems, providing a global coverage with about 20 – 30 satellites in medium-Earth orbit. The project promises that the system will be able to monitor even polar regions; the capability of multiple viewing angles is expected to tackle the problem of terrain blocking.

The Galileo search and rescue component will also provide a basic communication component that is absent in the current Geosar and Leosar system. While the "Forward Link Alert Service" is promised to be fully backward compatible with the current operational COSPAS-SARSAT components and interoperable with all other planned MEOSAR elements, detects activated distress beacons and notifies the appropriate rescue body, there is a second feature, called "Return Link Service". This component will allow the satellite to send a return message to the emergency beacon and let individuals know that their distress signal has been received and help is on its way.

Galileo representatives said that four satellites with search and rescue transponders will be used to demonstrate the Galileo MEOSAR services.