NASA develops improved search and rescue system

Posted by Emma Woollacott

NASA is working on new satellite-aided search and rescue technology that will make it quicker to find people in distress.

The Search and Rescue Mission Office at NASA's Goddard Space Flight Center, in collaboration with several government agencies, has developed a next-generation search and rescue system, called the Distress Alerting Satellite System (DASS).

The team is now testing the new system, and expects to get it up and running in the next couple of years after a complete constellation of DASS-equipped satellites is launched.

DASS will be able to almost instantaneously detect and locate distress signals generated by 406MHz beacons installed on aircraft and vessels or carried by individuals.

The satellite-based instruments used to relay the emergency signals will be installed on the US military’s GPS, a constellation of 24 spacecraft operating in mid-Earth orbit.

Under the current system, which dates from the mid-1980s, the repeaters are placed on NOAA weather satellites operating in low-Earth and geostationary orbits.

The Low Earth Orbit spacecraft orbit the Earth 14 times a day and use the Doppler effect to help pinpoint the location of a signal. However, a satellite may not be in position to pick up a distress signal the moment a user activates the beacon.

And NOAA's geosynchronous weather satellites can only locate a beacon if it contains a navigation receiver that encodes and transmits its position.

DASS overcomes these limitations, said Mickey Fitzmaurice, space systems engineer for the NOAA Search and Rescue Satellite-Aided Tracking (SARSAT) program.

"With a mid-Earth orbit search and rescue capability provided by GPS, one emergency signal goes off, and six satellites will be in view," he says. "Almost instantly, I can begin processing the signal to determine its precise location. Right now, it can take an hour or more before we can even act on a signal."

Currently, nine GPS satellites are up and running, with another 12 planned.

The US isn't alone in using mid-Earth orbiting spacecraft for its search and rescue instruments. Europe has begun development of a search and rescue capability on its Galileo system, as have Russia on its GLONASS system and China on its Compass system.

There's information about beacon registry here.