Galileo satellites are placed in medium orbits, at 23 222 km altitude along three orbital planes so that a minimum of four satellites will be visible to user receivers at any point on Earth once the constellation is complete. Photo from ESA.
Today is International 406 Day, a day marked for raising awareness about the importance of emergency beacons and the satellites that transmit their SOS signals, according to the European Space Agency (ESA).
The day takes its name from the radio frequency used by international Cospas-Sarsat beacons, and the US order of today’s date.
Emergency beacons are used aboard boats, ships, and aircraft, and are even carried by hikers in the wilderness- in other words, anywhere beyond the reach of standard phone-based emergency services. They’re generally small, often no bigger than a flashlight.
“All the same, an SOS signal can reach the authorities surprisingly swiftly, within a few minutes,” says ESA. “First the signal from the beacon is detected automatically by the search and rescue payload aboard participating satellites – often more than one at once – then pinpoints its source on Earth’s surface.”
“Next, this information is relayed – via a set of stations on the corners of Europe, in the case of Galileo-detected signals – then passed to the nearest national rescue centre, at which point the rescue can begin.”
Galileo refers to the constellation network of satellites over Europe, named for the famous Italian astronomer, physicist, and engineer.
When Skipper Kevin Escoffier had his boat smashed to pieces by waves during a solo round-the-world yacht race last year, his life raft automatically activated a rescue beacon that was picked up by satellites. He was rescued within minutes.
The International Cospas-Sarsat Programme that Galileo’s satellites are a part of is the result of the cooperation of 45 nations and agencies, and has helped save thousands of lives since it was established in 1982.
“Galileo’s participation in Cospas-Sarsat has led in turn to a service innovation,” says ESA. “From last year, Galileo has been replying to SOS signals with ‘return link messages,’ assuring those in peril that their signals have been received and help is on the way.”