Search and Rescue Satellite-Aided Tracking (SARSAT)

Introduction

The National Environmental Satellite, Data, and Information Service (NEDIS) operates satellites that monitor daily weather and surface condidtions for the National Oceanic and Atmospheric Administration (NOAA). In addition to weather and environmental sensors, Search and Rescue Satellite-Aided Tracking (SARSAT) payload, which are provided by Canada and France, are carried on the polar orbiting spacecraft. Russia also operates polar-orbiting satellites as part of their spacecraft navigation systems and some carry similar SARSAT payloads. The Russian SARSAT payloads are called COSPAS.

COSPAS and SARSAT are both being used in an international cooperative search and rescue (SAR) satellite effort. The COSPAS/SARSAT Project objective is to help save lives of aviators and mariners who are in distress and transmit emergency signals to the satellites that pass above them. Aircraft carry fixed Emergency Locator Transmitters (ELTs) that are normally triggered by the impact of a crash. Ships and boats carry floating Emergency Position-Indicating Radio Beacons (EPIRB) that are activated by immersion in water. Both the ELT ane EPIRB can also be activated manually.

The common operational COSPAS/SARSAT ELT and EPIRB radio frequency is 121.5 MHz. This frequency provides the location of an aviator or mariner in distress with an accuracy of 5-10 miles. The experimental ELT EPIRB 406 MHz radio frequency will provide the location to within 1-3 miles.

How Does It Work?

1. Aviators and mariners in distress use an ELT or EPIRB to transmit an emergency signal to the SARSAT and/or COSPAS satellites.
2. The ELT or EPIRB emergency signal, received by the SARSAT and /or COSPAS satellites, is retransmitted to the ground receiving station called a Local User Terminal (LUT).
3. The LUT receives the signal from the satellite, processes the signal, and estimates the location of the aviator or mariner in distress.
4. This position is then passed on to the Rescue Coordination Center (RCC) who coordinates the search forces.
5. Search and Rescue (SAR) forces are dispatched by either the U.S. Air Force or U.S. Coast Guard. This may include fixed wing aircraft, helicopters, ships, boats, ground search parties, and may also include the use of commercial airlines or commercial ships.

SARSAT/COSPAS Polar-Orbiting Satellites