Delving into the COSPAS-SARSAT system can quickly have you drowning in alphabet soup.
Governments love acronyms, abbreviations and virtually unknown terminology in general, but bear with me and we’ll spoon through it to reveal a coming improvement that should excite anyone who goes where they might need rescuing.
Let’s start with the international COSPAS-SARSAT. This organization’s moniker is a combination of Russian and English. Spelled out, it reads Cosmicheskaya Sisteyama Poiska Avariynich Sudov – Search and Rescue Satellite-Aided Tracking.
The system is free to users and it has saved more than 35,000 lives since the U.S., Canada, the USSR and France built it back in the 1970s. That averages out to an impressive 5.9 rescues per day.
The system consists of three segments: user, space and ground.
The user segment includes emergency beacon transmitters for marine, aviation and land use. More than 1.4 million distress beacons made by about 50 manufacturers are registered with COSPAS-SARSAT around the world. These include the manually and automatically deploying beacons for ships, boats and planes, and personal locator beacons for people on the ground.
Emergency transmissions from these beacons are received by satellites in the space segment, which includes two satellite constellations and is getting a third.
Five low Earth orbit search-and-rescue satellites comprise the LEOSAR constellation that can locate beacons using Doppler processing.
These satellites travel in polar orbits (pole to pole), traveling only 1,000 kilometers above the earth, which means they can only “see” a limited amount of surface area at any given time.
The orbits are fixed, while the earth rotates underneath them, and an emergency beacon must be within view of a satellite for its signal to be picked up.
Doppler location processing works by noting how the frequency of the beacon transmission changes as heard by the satellite passing overhead. Ground stations know the exact position of each satellite at any given instant and can use the apparent frequency shift to compute the position of the beacon.
The geosynchronous orbit (GEOSAR) satellite constellation is the second satellite group in place, with seven satellites orbiting 35,786 kilometers out in space. Five more satellites are scheduled to be in place by 2019.
A satellite in geosynchronous orbit travels with the rotation of the earth and stays in the same place above a spot on the earth’s surface. Its high orbit allows it to see almost an entire hemisphere (it misses the extreme polar regions) and, although it alerts instantaneously upon receiving a distress signal, it can’t locate the beacon sending it unless the transmission includes GPS coordinates.
This has always been a good reason to buy a beacon with built-in GPS.
The mid-Earth orbit search-and-rescue (MEOSAR) system will use upgraded GPS system satellites from the United States Navstar, Russia’s GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema or “global navigation satellite system”) and those in the European Galileo system. These spacecraft orbit at between 19,000 and 24,000 kilometers out in space, roughly midway between the lower LEOSAR and higher GEOSAR constellations in what are therefore called mid-Earth orbits.
The ground segment is made up of local user terminals (LUTs) that accomplish different jobs. LUT antennas receive emergency beacon messages relayed by the satellite systems. They detect the signals, aid in the beacon location process and then pass the message on to one of the 31 mission control centers (MCCs) around the world, where they are validated and distributed to rescue coordination centers.
Then the closest appropriate emergency responders are selected and tasked with the rescue mission.
So, what’s the big deal about MEOSAR’s part in all this? Well, the updates to the GPS satellites will be accompanied by changes in everything from the emergency beacons we use to the way the satellites interact with the ground stations.
Today, it can take as long as 45 minutes for a beacon to be located by COSPAS-SARSAT. When MEOSAR is fully functional it will reduce beacon-detection times to seconds and beacon location to about five minutes.
Search-and-rescue teams will have the beacon’s GPS location at their fingertips, even if no GPS position is sent in the beacon’s emergency message.
And, perhaps most comforting of all, the system will send a message to the beacon telling its operator that his emergency message has been received and help is on the way — no more wondering whether or not you will be found before your beacon’s battery runs out.
MEOSAR will ultimately include 72 operational satellites: 25 each from the U.S. Navstar, Russian GLONASS and European Galileo GPS systems.
Right now, there are only about a dozen satellites in the LEOSAR and GEOSAR constellations doing everything, and it is possible for terrain features like mountains and cliffs to block beacon transmissions and cause delays in the rescue process.
With 72 MEOSAR satellites also listening for beacon transmissions, there will almost always be multiple satellites overhead, no matter where an emergency occurs.
MEOSAR will locate a beacon by having multiple satellites measure their distances from it. This is how the GPS navigation system works, but in reverse. The GPS receiver on your boat or in your hand fixes your position on the earth by measuring its distance from the satellites.
MEOSAR has the satellites in space measuring their distance from the beacon. The LEOSAR satellites are expected to be phased out and replaced by the MEOSAR birds.
There are currently 12 MEOSAR local user terminals to receive distress messages from satellites and three are under construction to be ready in 2016.
MEOSAR now has seven mission control centers, with two more to be ready in 2016. MEOSAR should attain early operating capability in 2016 and full capability by 2018.
If you currently have a marine EPIRB (emergency position indicating radio beacon) on your boat, an ELT (emergency locating transmitter) on your plane or a PLB (personal locator beacon) for use on land or water, keep in mind that you’ll need to replace it with a second-generation beacon to use all of MEOSAR’s advantages. Current models don’t have the capability to receive emergency message confirmation by return link.
Goals for the new beacons also include a cancellation button, possible in-flight activation for aircraft beacons and additional data transmission fields for things like battery status, user status, temperature and other information that could be important to rescuers and rescuees.
Improved homing capability — possibly even including AIS in the marine environment — is in the works.
We went through a lot of discussion, saw frequent changes and had to sit through a waiting period before GPS replaced Loran C as the standard for electronic navigation. Saying it was worth the wait doesn’t begin to describe how it revolutionized nearly everything we do outdoors.
COSPAS-SARSAT is keeping us safe now, but we will be a lot safer once MEOSAR is fully functioning. And, won’t it be nice to take it for granted just like we do GPS?