For more than 30 years, sailors in distress have relied on emergency beacons to summon help from anywhere in the world. Once triggered, these devices beam a signal skyward to a network of satellites that detect the message and then retransmit it back to Earth.
By almost any measure, this system — operated through the international Cospas-Sarsat search and rescue program — is an overwhelming success (Cospas is a Russian acronym for satellite search and rescue similar to the English acronym SARSAT). Since coming online in 1982, the program has led to more than 11,000 rescues over land and sea, saving more than 40,000 lives. About half of those rescues involved mariners.
Now, the network of low-Earth-orbit and geostationary satellites that makes those rescues possible is undergoing a once-in-a-generation upgrade. The U.S., Russia and the European Union will use a new generation of satellites that will improve upon the existing network’s capabilities. The new program is called MEOSAR.
“The MEOSAR system will offer the advantages of both (existing satellite) systems without their current limitations,” said U.S. Coast Guard Lt. Cmdr. Aaron J. Ortenzio, the agency’s SARSAT Liaison Officer.
Those systemic improvements should translate into faster rescues during emergencies.
“The current system does not provide, at the same time, a global and real-time coverage,” said Benoit Helin, technical officer for the Cospas-Sarsat Secretariat based in Montreal. “The MEOSAR system will provide global, real-time detection and independent location of beacons in distress mode.
He continued, “It is anticipated that the real-time monitoring of Cospas-Sarsat distress messages will improve the number of saved every year, in particular by speeding up the rescue.”
The idea for an international satellite-based search and rescue program dates back at least to the 1970s. But in 1979, the U.S., Russia, France and Canada established the Cospas-Sarsat program, which alerts rescue authorities around the world to 406-MHz distress signals from emergency beacons. Unlike some subscription-based beacon products, Cospas-Sarsat has operated no fees to users since its inception.
Cospas-Sarsat itself is based on international cooperation between the more than 40 participating nations around the world. The U.S., Canada, Russia and France oversee the program.
“The (Cospas-Sarsat) system is run by national administrations that cooperate together to exchange distress data,” Helin said. These administrations also “make sure distress messages received by ground stations are well transmitted to local search and rescue forces and to the country where the distress beacon is registered.”
At its core, this system is relatively simple: Special equipment installed on satellites circling above the Earth detect emergency distress signals then transmit them to ground stations on Earth. From there, the messages are relayed to the appropriate search and rescue agencies to coordinate help.
In the U.S., the National Oceanic and Atmospheric Administration (NOAA) oversees the satellite search-and-rescue infrastructure, while the Coast Guard and Air Force are charged with performing the rescues, according to Jerry Nardi, a senior scientist with the McMurdo Group, which sells emergency beacons and is developing MEOSAR ground facilities for the U.S.
Initially, this system relied only on transponders placed on low-Earth-orbit, or LEO satellites, circling about 500 miles overhead. Using the Doppler effect, these satellites can routinely determine a beacon’s location to within about three-quarters of a mile, giving rescue crews a good idea where to look. But these components installed on weather satellites have some notable limitations.
The five remaining LEOSAR satellites do not cover the entire globe at once, meaning there can be a delay from the time a beacon is triggered to when the nearest satellite receives the message. On average, it takes 90 minutes for a satellite to come into signal range, but it can take several hours. Multiple satellite passes are sometimes necessary to determine a beacon’s location.
More recently, Cospas-Sarsat integrated a half-dozen geostationary satellites flying some 22,000 miles above the Earth into the system. These so-called GEOSAR satellites detect distress signals almost immediately, but they cannot determine where the signal is coming from. Some emergency beacons transmit latitude and longitude information in the distress message, but those that do not must rely on LEOSAR satellites to determine the beacon’s location. GEOSAR satellites also have limited visibility in the polar regions.
Medium distance works best
MEOSAR effectively combines the best attributes of LEO and GEO systems into a single satellite infrastructure. This is accomplished by putting MEOSAR transponders on board medium-Earth-orbit navigation satellites: 24 U.S. GPS, 24 Russian GLONASS and 24 European Union Galileo spacecraft. These satellites orbit at 12,000 miles above the Earth and although they don’t appear to hang over a single point like a geostationary spacecraft, the large numbers in each constellation mean that every point on Earth will be continuously monitored.
“Once it’s up there, the response time for recognizing a beacon going off is almost instantaneous,” Len Bastien, an assistant deputy minister in the Canadian Department of National Defense, said of MEOSAR.
“When (rescue crews) drop into a site, 1,000 meters or 100 meters can make a big difference, especially at night and especially under very difficult conditions,” Bastien added. “We are giving our search and rescue (crews) a better chance of mission success by providing this capability.”
In addition to potentially faster rescues, the new system will have substantially more satellites, meaning more than one will detect most distress signals. As of 2014, there were five LEO and six GEO satellites in orbit, whereas the MEOSAR network will total 72 satellites with transponders aboard.
“Because of the number of satellites planned and the characteristics of their medium-altitude Earth orbits, the MEOSAR system will provide high levels of redundancy and resistance to beacon-to-satellite blockages,” said Ortenzio, Coast Guard SARSAT officer.
The U.S. has already commissioned 20 satellites in its GPS system with MEOSAR hardware, while the E.U. has commissioned 10 satellites in the European Galileo space system.
The U.S. and Canada have partnered on the MEOSAR program, and the Canadian government has agreed to spend about $220 million to develop and build the search-and-rescue hardware mounted on American satellites, according to the U.S. Coast Guard.
Current projections show MEOSAR entering an early operational stage later this year or sometime in 2017, but it won’t be fully operational until 2018. However, search and rescue agencies around the world are already starting to receive distress signals from MEOSAR equipment on board some satellites.
In April, three days after New Zealand’s test program went live, MEOSAR satellites heard a hiker’s distress signal in a remote mountain range in that country. A 53-year-old hiker broke his leg in two places after a fall but was able to activate his personal beacon.
According to a news release from Maritime New Zealand, the MEOSAR setup worked just as intended.
“The extra time created by receiving the signal faster was invaluable, and potentially lifesaving,” Mike Hill, of Rescue Coordination Centre New Zealand, said in the release. “It meant we could get the search operation underway earlier, and that made all the difference with the limited daylight hours that are available at this time of year.”
Four months later, in August, MEOSAR captured a distress signal from a small plane following an emergency landing in a field in Argentina.
U.S. agencies also are beginning to integrate MEOSAR into search and rescue capabilities. John Leslie, a spokesman for NOAA, said the U.S. Coast Guard could begin training on the new platform later this year.
“The U.S. and France are currently in the process of commissioning their respective Mission Control Centers to accommodate the processing and distribution of MEOSAR data with the current LEOSAR and GEOSAR data,” he said.
Ground station improvements
Progress with MEOSAR is also occurring here on Earth. In the U.S., ground stations have been built in Hawaii and Florida, and similar facilities exist in France, Canada, Russia, Turkey, Australia, New Zealand, Brazil and Argentina. Honeywell and McMurdo Group are among the companies building these facilities.
Advances in the MEOSAR rollout come as a key piece of the existing satellite search-and-rescue infrastructure is winding down. LEOSAR is scheduled to be phased out starting in 2020 as the existing satellites reach the end of their useful lives. Until then, the LEO and GEO satellite network will complement MEOSAR for satellite search and rescue.
Currently, there are nearly 1.6 million 406-MHz emergency beacons in use around the world. This number includes EPIRBs found on ships and sailboats, personal beacons used on land and sea, and emergency locator transmitters (ELTs) on aircraft. Users will not notice any difference as the MEOSAR network gradually comes online between now and 2018.
However, the new satellite constellation will likely lead to advances in emergency beacon technology. One feature expected in future beacons is called return link service, which would let users know the satellite has received their distress signal. Future beacons also could provide more accurate location information to within about 100 meters.
“The MEOSAR system will allow the development of a new generation of beacons, with additional features and functionalities that will benefit the user and the search and rescue forces,” said Helin of Cospas-Sarsat.
For now, Cospas-Sarsat and its partners of more than 40 nations around the world are working toward a seamless transition between the satellite networks. The next generation of satellite search and rescue should make an already successful system even more so.
Casey Conley is a staff writer for Ocean Navigator and Professional Mariner magazines and is the editor of American Tugboat Review.