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USA in Space, Fourth Edition

Search and Rescue Satellites

by T. Parker Bishop

Date: Beginning September 1, 1982

Type of spacecraft: Search and rescue satellites

Search and Rescue Satellites detect emergency beacons of downed aircraft, capsized boats, and individuals involved in exploration. In its first few years, the COSPAS/SARSAT program helped to save more than thirteen hundred lives.

Summary of the Satellites

COSPAS/SARSAT is an international program using satellites to aid in search-and-rescue operations. SARSAT stands for Search and Rescue Satellite-Aided Tracking. COSPAS is a Russian acronym for Space System for Search of Vessels in Distress.

The idea for a satellite-aided search-and-rescue program arose at almost the same time that artificial satellites were first placed in Earth orbit. It was not until the 1970’s, however, that the National Aeronautics and Space Administration (NASA) began to experiment with the Doppler effect using the Nimbus satellites. The Doppler effect is the apparent change in frequency (the number of wave crests passing a point per unit of time) of an electromagnetic wave when an object moves toward or away from the source of the wave. A satellite in low-Earth orbit would observe an emergency beacon to have a higher frequency as it approached the beacon and a lower frequency as it receded from the beacon. This frequency shift allows the satellite to calculate the location of the beacon’s source. The Nimbus satellites succeeded in locating weather buoys, drifting balloons, and other remote sensors, and a search-and-rescue system was proved to be feasible.

The first operational Doppler data collection system was the French ARGOS carried on the U.S. National Oceanic and Atmospheric Administration’s TIROS (Television Infrared Observations Satellite). Later systems evolved from ARGOS.

In 1976, the COSPAS/SARSAT program became an international effort when the United States, France, and Canada signed agreements to test a satellite-aided search-and-rescue system. The United States would contribute its Advanced TIROS-N (ATN) weather satellites, Canada would supply electronic repeaters (devices that receive a radio signal, amplify it, and relay it to a ground station), and France would supply electronic processors for collection of identification data transmitted by the system’s users. In 1980, the Soviet Union joined the program by agreeing to place the same type of electronic equipment in its Kosmos satellites. The system became operational on September 1, 1982.

Other countries began participating in the system, although their participation was limited to ground operation of a local user terminal and/or a Mission Control Center. Local user terminals receive distress signals relayed from the repeaters in the satellites. Mission Control Centers collect information and send it to the appropriate rescue control center. In 1981, Norway and Sweden began operating local user terminals. The United Kingdom joined in 1983; Finland, in 1984. Norway and the United Kingdom also operate Mission Control Centers. Additional nations joined the program with the passage of time.

A number of other countries (Chile, Denmark, India, Italy, Japan, Pakistan, Sweden, Switzerland, and Venezuela) either use the system, operate a user terminal, or are discussing possible operation of user terminals or control centers

The Components and Operation of the Cospas-Sarsat System. (International Cospas-Sarsat Programme)

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COSPAS/SARSAT works in the following manner. An emergency transmitter—either an emergency locator-transmitter (ELT) or an emergency pointing/indicating radio beacon (EPIRB)—is activated when an emergency occurs. ELTs are carried on general aviation aircraft, and EPIRBs are carried on marine vessels that venture into open ocean. The signal from an ELT or EPIRB has a frequency of 121.5 or 243 megahertz. The signal is received by a COSPAS/SARSAT satellite and relayed to a local user terminal at a frequency of 1544.5 megahertz. Some more advanced ELTs can transmit a 406 megahertz signal that provides data on the sender’s identification and nationality as well as the transmission’s time and location. If necessary, the information can be stored until the satellite is in range of a ground station. After the information is processed by the local user terminal, it is relayed to the appropriate Mission Control Center, which may be in another country. The Mission Control Center then passes the information on to a rescue control center, which is then responsible for the rescue.

The type of rescue effort varies with geography, national boundaries, and available resources. In the United States, the Air Force, sometimes with help from the Civil Air Patrol, coordinates inland airplane rescue attempts. The Coast Guard is called on for rescue attempts in the ocean to a distance of 320 kilometers from the U.S. coastline; farther out, the Air Force is responsible for searches. COSPAS/SARSAT’s pinpointing of the signal sender’s location helps reduce the amount of money spent on the search and, more important, time spent finding downed aircraft or ships in distress. Studies show that the survival rate for airplane crash victims is 50 percent if they are rescued within eight hours. If the rescue takes place more than two days after the disaster, however, the chance of survival drops to 10 percent.

Contributions

In the 1970’s, using satellites in search and rescue was proven feasible. In the early 1980’s, enough satellites were placed in orbit and enough ground stations were set up to allow the system to operate.

The first COSPAS/SARSAT rescue took place in September, 1982. A young couple’s plane went down in British Columbia in July, 1982, and the Canadian government launched an extensive search that ultimately cost nearly two million dollars. The couple was not found, and the search was stopped. The young man’s father, along with a pilot and a friend, decided to embark on their own search-and-rescue mission, which continued into September, 1982.

During this search, however, their plane crashed in a mountainous, tree-covered area. They were injured, but alive. An ELT had been activated by the crash, and as Soviet COSPAS 1 passed over, it relayed the information to the Trenton, Ontario, Air Rescue Station. A rescue control center was contacted, and the three victims became the first persons to be rescued with the aid of a satellite.

The two disasters serve as contrasting examples of search-and-rescue operations. The location of the first crash was not known, and consequently, much time and money were expended in searching. The second crash location was known to within 22.5 kilometers, so only a relatively small area had to be searched; costs were much lower, and the victims were found while they were still alive.

In July, 1985, the COSPAS/SARSAT steering committee, which includes experts from Canada, France, the Soviet Union, and the United States, adopted the 406 megahertz frequency for signals broadcast by ELTs. Because the 406 megahertz signal allows for more precise location calculations than does the 121 megahertz signal, it makes faster rescues possible. Moreover, such a signal can carry identification data.

A problem that plagues the COSPAS/SARSAT system is the large number of false alarms. In 1988, the false alarm rate was 98 percent for ELTs and more than 50 percent for EPIRBs. False alarms are caused by unintentional activation of an ELT or EPIRB beacon resulting from improper handling, equipment failure, or improper shipment or testing. Because each distress signal must be tracked down, much time and effort are wasted. False alarms probably can be reduced by better enforcement of laws governing the use of emergency frequencies, redesign of equipment so that it is harder to trigger a false alarm, and better education for ELT and EPIRB users.

Context

Before the COSPAS/SARSAT program, search-and-rescue operations were conducted on a hit-or-miss basis. During the 1970’s, NASA showed that it was possible to locate radio signal sources on Earth by making use of the Doppler effect, and this technology spurred the development of COSPAS/SARSAT. New knowledge has been gained in the area of locating points on Earth’s surface, and as a result, rescue teams can locate disaster victims much more quickly.

COSPAS/SARSAT saves money as well as lives. When the area to be searched is a few square kilometers instead of hundreds or thousands of square kilometers, fewer searches are needed. More efficient searches also mean that rescue planes or ships can be used for shorter times. COSPAS/SARSAT has effected savings of $20 million per year, according to estimations by Owen Heeter, commander of the Air Force’s Aerospace Rescue and Recovery Service.

COSPAS/SARSAT is important for one other reason: international cooperation. The United States and the Soviet Union were partners in this program almost from its beginning. For nearly six years, it functioned only on a memorandum of understanding, but on July 1, 1988, an international agreement requiring nations to cooperate in COSPAS/SARSAT was signed by the United States, Canada, France, and the Soviet Union. William E. Evans, undersecretary of commerce for Ocean and Atmosphere, signed for the United States. This agreement is binding for the first ten years, with automatic renewal every five years thereafter. Countries and organizations such as the United Nations International Maritime Organization can require that ships and/or aircraft have the emergency 406 megahertz beacon on board. In the late 1980’s, NASA was trying to develop low-cost 406 megahertz ELTs.

As of 2005, there were seven COSPAS/SARSAT satellites in low-altitude Earth orbit and three satellites in geostationary orbit, eighteen ground segment providers, and eight user states. One SARSAT satellite had suffered malfunctions, resulting in intermittent loss of service, that could affect an entire or just partial satellite pass. More than 800,000 distress beacons were estimated to be deployed. By 2003 more than seventeen thousand people had been rescued in more than 4,800 responding incidents. NASA and others continue to seek new methods to cut costs and time in search-and-rescue operations while saving even more lives.

See also: Amateur Radio Satellites; Cooperation in Space: U.S. and Russian; National Aeronautics and Space Administration; Saturn Launch Vehicles; SMS and GOES Meteorological Satellites; Telecommunications Satellites: Maritime; TIROS Meteorological Satellites.

Further Reading

1 

Andrade, Alessandra A. L. The Global Navigation Satellite System: Navigating into the New Millennium. Montreal: Ashgate, 2001. Provides an international view of issues of availability, cooperation, and reliability of air navigation services. Attention is specifically paid to the American GPS (Global Positioning System) and Russian GLONASS systems, although the development of the Galileo civilian system in Europe is also presented.

2 

Bailey, James T. “Satellites Answer SOS.” Mariner’s Weather Log 32 (Spring, 1988): 8-11. A nontechnical description of search-and-rescue satellites, this article requires minimal technical knowledge. Contains several photographs and one illustration showing how the COSPAS/SARSAT system works and features stories about searches that demonstrate the usefulness and cost-effectiveness of the COSPAS/SARSAT system. Emphasizes international cooperation.

3 

Gavaghan, Helen. Something New Under the Sun: Satellites and the Beginning of the Space Age. New York: Copernicus Books, 1998. This book focuses on the history and development of artificial satellites. It centers on three major areas of development—navigational satellites, communications satellites, and weather observation and forecasting satellites.

4 

Haggerty, James J. Spinoff 1984. NASA TM-85596. Washington, D.C.: Government Printing Office, 1984. This multicolor pamphlet contains a summary of NASA’s major accomplishments in space and the ways in which those accomplishments have benefited humankind. One page is devoted to a brief description of how the COSPAS/SARSAT system operates. Illustrated. For general audiences.

5 

Kachmar, Michael. “SARSAT/COSPAS: Saving Lives Through Cooperation In Space.” Microwaves and RF 23 (October, 1984): 33-35. This journal contains a news section in which uses of microwaves and radio frequency waves are described. Includes photographs. Technical language is used mostly without explanation, but some terms are defined in the text.

6 

McElroy, John H., and James T. Bailey. “Saving Lives at Sea . . . Via Satellite.” Sea Technology 26 (August, 1985): 30-34. A nontechnical description of the COSPAS/SARSAT international satellite network. Includes illustrations of a rescue at sea and a discussion of searches and their costs. Suitable for general audiences.

7 

National Aeronautics and Space Administration. COSPAS/SARSAT. Greenbelt, Md.: Author, 1986. Describes the COSPAS/SARSAT system and gives a brief history of how the system was developed. Outlines the operation’s successes and the ways in which it will expand in the future. Contains color diagrams. Suitable for general audiences.

8 

---. Space Network Users’ Guide (SNUG). Washington, D.C.: Government Printing Office, 2002. This users’ guide emphasizes the interface between the user ground facilities and the Space Network, providing the radio frequency interface between user spacecraft and NASA’s Tracking and Data-Relay Satellite System, and the procedures for working with Goddard Space Flight Center’s Space Communication program.

9 

National Research Council Staff. The Global Positioning System: A Shared National Asset: Recommendations for Technical Improvements and Enhancements. Washington, D.C.: National Academy Press, 1995. This book provides insights into the global positioning satellites and recommends some improvements to enhance military, civilian, and commercial use of the system.

10 

Ola, Per, and Emily D’Aulaire. “The Starduster’s Last Flight.” Reader’s Digest 131 (July, 1987): 75-80. This is a nontechnical account of a successful search-and-rescue operation. It is part of the Drama in Real Life series of articles that appears in Reader’s Digest. Written as a historical account of an air disaster, with a description of the efforts of the Air Force Rescue Coordinator Center to help in the search. Suitable for general audiences.

11 

United States Coast Guard. National Search and Rescue Manual. Washington, D.C.: Author, 1986. This two-volume work gives detailed information on the procedures for performing search-and-rescue operations. These manuals could be used in training exercises. Satellite-aided search-and-rescue operations are discussed. For general audiences.

12 

United States Department of Commerce. NESDIS Programs, NOAA Satellite Operations. Washington, D.C.: Author, 1985. This publication provides a very brief description of the COSPAS/SARSAT system and a diagram of how the system operates. Most of this publication covers other topics, such as the weather satellites of the NESDIS program. For general audiences.

13 

United States Department of Transportation. 1986 SAR Statistics. Washington, D.C.: Author, 1986. This publication offers tables, photographs, and diagrams detailing search and rescue statistics for 1986. Does not distinguish between satellite-aided and nonsatellite-aided rescues. For general audiences.

Citation Types

Type
Format
MLA 9th
Bishop, T. Parker. "Search And Rescue Satellites." USA in Space, Fourth Edition, edited by David G. Fisher, Salem Press, 2019. Salem Online, online.salempress.com/articleDetails.do?articleName=USSpace2E_0201.
APA 7th
Bishop, T. P. (2019). Search and Rescue Satellites. In D. G. Fisher (Ed.), USA in Space, Fourth Edition. Salem Press. online.salempress.com.
CMOS 17th
Bishop, T. Parker. "Search And Rescue Satellites." Edited by David G. Fisher. USA in Space, Fourth Edition. Hackensack: Salem Press, 2019. Accessed December 14, 2025. online.salempress.com.