Digital technology will speed search-and-rescue efforts

The government has found a way to switch from analog to digital satellite-based search and rescue, but it could take until 2020 for the system to be fully operational, federal officials said.

The government's existing system - Search-and-Rescue Satellite-Aided Tracking (SARSAT) -- is nearly 30 years old and has relied on National Oceanic and Atmospheric Administration weather satellites to save more than 27,000 lives worldwide. The satellites scan for distress signals from emergency beacons on planes, boats and people. The new approach, called the Distress Alerting Satellite System, would rely on the U.S. military's Global Positioning System, an array of 24 spacecraft, to detect the type and precise location of beacons.

"It will eliminate wait time," said Dave Affens, NASA search-and-rescue mission manager, during a call with reporters on Monday. "The new system is designed to work within a few minutes" compared to the hour-long wait period now needed for location information.

Under the current operation, some NOAA spacecraft orbit the Earth 14 times a day, so a satellite might not be in position to pick up a distress signal the moment a user activates a beacon, according to officials at NASA, which is developing the replacement technology. Other NOAA satellites can be obstructed by terrain.

But with orbiting GPS technology, when one emergency signal goes off, six satellites will see it, allowing rescuers to almost instantly begin pinpointing its precise location. Europe, Russia and China are developing satellites with compatible technology modeled after DASS. So the time frame for deployment of the GPS-based search-and-rescue system might be shorter if the partner countries launch their spacecraft first, Affens said.

The government already knows this method works because prototypes are flying on GPS satellites supporting other missions. The Air Force will start launching GPS satellites dedicated to DASS around 2015 and will position a full fleet by 2020. The demonstration equipment in space today is inadequate because it cannot filter out signals from other frequencies, such as those from cell phones. That means the instruments can experience periodic disruptions.

"If our satellite is picking up all that noise, as well as our search-and-rescue band, we're effectively getting jammed," Mickey Fitzmaurice, SARSAT systems engineer at NOAA, said during an interview. The satellites under development would receive only the search-and-rescue frequency band. The government is working with contractors from Lockheed Martin Corp. on specifications for building the satellites, which can cost anywhere from $750 million to $1 billion, according to Fitzmaurice. Because the devices are so costly and GPS-based search and rescue is a secondary priority compared to other payloads such as imagers for weather satellites, it will take a few years to build the dedicated satellites, he added.

Lt. Col Charles Tomko, commander of the Air Force Rescue Coordination Center, compared the search-and-rescue technology overhaul to the move from analog to digital television. "The digital signal is clearer, it's longer range," he said during Monday's call.