Space: Search and Rescue Satellite Aided Tracking (SARSAT)

© 2008 FrontLine Defence (Vol 5, No 6)

Search and Rescue Instruments Save Lives
The first Canadian SARSAT satellite was successfully launched on the 28th of March 1983, and the program continues to be a great success. Its purpose is to save lives and resources by removing the search from search and rescue.

This spring, the SARSAT Program, supported by the Director General Information Management Project Delivery (DGIMPD) and the Director General Information Management Technology (DGIMT) celebrated the 25th anniversary of Canadian participation in space for search and rescue.

Every month, hundreds of lives worldwide are saved thanks to this polar orbiting low Earth orbit satellite system. A SARSAT satellite can detect people in distress who are using a compact 406 MHz emergency beacon. The satellite receives and then relays the alarm to a satellite tracking station called a Local User Terminal (LUT), which then calculates the beacon’s location using the Doppler shift principle. This information is then passed to one of many Mission Control Centres (MCCs) around the world and then to the SAR agencies that conduct the search and rescue.

The Canadian Forces (CF) members working at the Canadian MCC (CMCC) located in Trenton, and the specialized DND rescue teams across the country, play an extraordinary role in rescuing people in distress, whether they are at sea, in the far North, or in a deep forest. Their due diligence and dedication contribute to the return of many people to their families. For many, SARSAT was the only alerting source to the trouble.

The system is a joint Canadian, French, Russian, and American venture. There are presently five operational SARSAT satellites orbiting the Earth, at an altitude of 850 kilometres.

As the satellites wear out (approximately every three or four years), new ones are launched to replace them. The next satellite is scheduled to be launched in ­February 2009, from the ­Vandenburg Air Force Base in California. More than 40 countries are currently participating in the program, and the number is growing every year. As of today, over 23,000 lives have been saved worldwide thanks to SARSAT.

New Generation Technology
The development of a new generation of SARSAT payload has just been completed, and the prototype unit will be delivered to the Department of National Defence this fall. The new design features a single band of operation at 406 MHz. In response to the SARSAT Council’s request, the 121.5 and 243 MHz alerting bands will no longer be supported for SARSAT operations after 1 February 2009. After that date, only 406 MHz beacons will be detected and processed.

The production of the two new SARSAT payloads should begin in 2009, with the first being launched in 2013 and the second in 2016. Both of these payloads will be integrated on the USA’s new weather satellite called the National Polar orbiting Operational Environmental Satellite (NPOESS).

Technology relentlessly marches on, and so it is with SARSAT. Therefore, research is currently under way in Canada to look further down the road at a new approach using Canadian designed and manufactured SARSAT payloads to be launched on future GPS satellites.

The current Doppler processing methodology has served SARSAT very well, but has many performance limitations. The new GPS approach relies on the 406 MHz emergency beacon being seen by three or more SARSAT payloads which are being simultaneously tracked by the LUT. It offers instantaneous alerting and improved location accuracy, and may be available about 2015. If proven successful, this new technology should carry SARSAT well into the middle of the century.
 
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Reprinted from IM Wired, a DND newsletter.
© Frontline Defence 2008

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