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martes, 6 de marzo de 2012

Astronomy: Galileo to spearhead extension of worldwide search and rescue service

Hi My Friends: A VUELO DE UN QUINDE EL BLOG., The global reach of Europe’s Galileo navigation system is being harnessed to pinpoint distress calls for rapid search and rescue. A major expansion of the humanitarian system will be tested over the next two years to make it even more effective. Cospas-Sarsat MEOSAR (Medium-Earth Orbit Search and Rescue) demonstration and evaluation phase task group meeting at ESTEC 1 March 2012

Credits: ESA/Anneke Le Floc'h
Founded by Canada, France, Russia and the US, Cospas-Sarsat began operations in 1982 with transponders on low-Earth orbiting satellites – known as ‘LEOSAR’. Using satellites including Europe's MetOp, their rapid orbital motion means that Doppler ranging can be performed to pinpoint the location of distress calls but it only a small area of Earth is covered at a time. It may take valuable time to line up with a ground station to relay a message – and it takes two satellite passes to pinpoint the distress call. In the 1990s Cospas-Sarsat introduced ‘GEOSAR’ coverage using geostationary orbit. With these satellites, including Europe's MSG, remaining in a fixed point in the sky, distress calls are detected and relayed immediately, although Doppler-based ranging is not possible. Credits: Cospas-Sarsat



For 30 years now the Cospas-Sarsat system has used orbital transponders on satellites including Europe's MSG and MetOp to pick up distress calls from ships and aircraft

Credits: Cospas-Sarsat
Artist's impression of the Galileo IOV satellite. Credits: ESA Like the US GPS and Russian Glonass, European Galileo satellites will carry Cospas-Sarsat MEOSAR (Medium Earth Orbit Search and Rescue) transponders. Galileo will also offer 'return link messaging' - so for the first time those in distress will receive replies confirming their distress call has been picked up and help is on the way Credits: NOAA Cospas-Sarsat's extension to MEOSAR (Medium Earth Orbit Search and Rescue) will extend its search and rescue coverage (the area outlined in red). On the ground the Galileo programme is contributing a Toulouse-based test bench, and a networked trio of MEOSAR ground stations – known as Local User Terminals – to cover Europe, based in Svalbard in the Norwegian Arctic, Cyprus and the Canary Islands. Existing LUTs are distributed on a per country basis, but it is an advantage of MEOSAR that fewer ground stations will be needed for greater coverage. Galileo engineers have introduced another innovation – for the first time those in distress will receive a reply, letting them know their signal was picked up and help is on the way.



Credits: Cospas-Sarsat

The global reach of Europe’s Galileo navigation system is being harnessed to pinpoint distress calls for rapid search and rescue. A major expansion of the humanitarian system will be tested over the next two years to make it even more effective. After rowing the Atlantic for 27 days, the six-man Atlantic Odyssey Sara G team suddenly capsized. The morning of 30 January saw them 800 km from land, clinging to their lifeboat in rough seas – but their distress call was detected from orbit. Rescue came within 14 hours.
The international Cospas–Sarsat satellite relay system has been making air and sea travel safer for 30 years, saving 24 000 lives along the way.
Cospas is a Russian acronym for ‘Space System for the Search of Vessels in Distress’, with Sarsat standing for ‘Search and Rescue Satellite-Aided Tracking’.
Satellites locate the source of distress calls from radio beacons on ships and aircraft, then local authorities are alerted.
“The service’s slogan is ‘taking the search out of search and rescue’,” explained ESA engineer Igor Stojkovic.
He participated in a week-long Cospas–Sarsat task group meeting from 27 February hosted at ESA’s ESTEC technical centre in Noordwijk, the Netherlands, with representatives from 21 nations, plus the European Commission and ESA for Galileo.
“We’ve finalised plans for a worldwide test campaign as we extend existing Cospas–Sarsat capabilities to international navigation satellites,” added Igor.
“Search and rescue packages are also being carried by US GPS and Russian Glonass satellites, though with most of Europe’s Galileo constellation being deployed within the next few years, Galileo is leading the way.”
Founded by Canada, France, Russia and the US, Cospas–Sarsat began with ‘transponders’ on low-orbit satellites.
“Their rapid orbital motion means that Doppler ranging can be performed to pinpoint the location of distress calls,” said Igor.
“However, only a small area of Earth is covered at a time, and it may take valuable time to line up with a ground station to relay a message – and it takes two satellite passes to pinpoint the distress call.”
In the 1990s Cospas–Sarsat introduced coverage from geostationary orbit, looking down from almost 36 000 km.
With these satellites remaining in a fixed point in the sky, distress calls are detected and relayed immediately, although their relative lack of motion means Doppler-based ranging is not possible.
“Now Cospas–Sarsat is moving to using navigation satellites in medium orbits,” added Igor.
“Navigation satellite constellations have been carefully designed for worldwide coverage, and can perform a combination of time- and frequency-based ranging for single-burst distress call positioning.”
The first medium-orbit transponder was launched on a Glonass satellite last year, with two more flying aboard Galileo satellites due for launch at the end of summer.
“These satellites will be the focus of our demonstration and evaluation phase, the results of which will set working standards for the operational system to follow from 2015,” said Igor.
Galileo engineers have introduced another innovation: for the first time those in distress will receive a reply, letting them know their signal was picked up and help is on the way.
ESA.
Guillermo Gonzalo Sánchez Achutegui
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