Defense Support Program


Air Force Space Command-operated Defense Support Program (DSP) satellites are a key part of North America's early warning systems. In their 22,000 miles-plus geosynchronous orbits, DSP satellites help protect the United States and its allies by detecting missile launches, space launches and nuclear detonations.


DSP satellites use an infrared sensor to detect heat from missile and booster plumes against the earth's background. In 1995, a new means of processing DSP data called Attack and Launch Early Reporting to Theater (ALERT) was brought on line. This capability provides improved warning of attack by short-range missiles against U.S. and allied forces overseas.

Numerous improvement projects have enabled DSP to provide accurate, reliable data in the face of evolving missile threats. On-station sensor reliability has provided uninterrupted service well past their design lifetime. Recent technological improvements include enhanced sensor resolution, increased on-board signal-processing capability to improve clutter rejection, and enhanced reliability and survivability improvements. In the 21st century, the Space-Based Infrared System (SBIRS) will replace DSP.


The program came to life with the first launch of a DSP satellite in the early 1970s. Since that time, DSP satellites have provided an uninterrupted early warning capability. The original DSP weighed 2,000 pounds and had 400 watts of power, 2,000 detectors and a design life of 1.25 years. In the 1970s, the satellite was upgraded to meet new mission requirements. As a result, the weight grew to 5,250 pounds, the power to 1,275 watts, the number of detectors increased by threefold to 6,000 and the design life was three years with a goal of five years.

The 21st Space Wing, located at Peterson Air Force Base, Colo., has units that operate DSP satellites and report warning information, via communications links, to the North American Aerospace Defense Command and U.S. Space Command early warning centers within Cheyenne Mountain, located near Colorado Springs, Colo. These centers immediately forward data to various agencies and areas of operations around the world.

The 50th Space Wing at Schriever AFB, Colo., provides command and control support for the satellites.

The Defense Support Program is managed by Space and Missile Systems Center (Air Force Materiel Command), Space Based Infrared System Program office at Los Angeles AFB, Calif. The office is responsible for development and acquisition of the satellites.

Typically, DSP satellites are launched into geosynchronous orbit on a Titan IV booster and inertial upper stage combination. However, one DSP satellite was launched using the space shuttle on mission STS-44 (Nov. 24, 1991).

DSP's effectiveness was proven during Desert Storm, when DSP detected the launch of Iraqi Scud missiles and provided warning to civilian populations and coalition forces in Israel and Saudi Arabia.

General Characteristics

Primary mission: Strategic and tactical missile launch detection

Contractor team: Thompson Ramo Woolridge (TRW) and Aerojet Electronics Systems

Weight: 5,250 pounds (2,386 kilograms)

Orbit altitude: 22,000 miles (35,200 kilometers)

Power plant: Solar arrays generate 1,485 watts

Height: 32.8 feet (10 meters) on orbit; 28 feet (8.5 meters) at launch

Diameter: 22 feet (6.7 meters) on orbit; 13.7 feet (4.2 meters) at launch

Date Deployed: 1970

Latest Satellite Block: Sat 23

Unit Cost: $400 million

Inventory: Classified

Point of Contact

Air Force Space Command, Public Affairs Office
150 Vandenburg Street, Suite 1105
Peterson AFB, Colorado 80914.
692-3731 or (719) 554-3731.



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