Defense Support Program Satellites
Published September 15, 2010
Air Force Space Command-operated Defense Support Program satellites are a key part of North America's early warning systems. In their 22,300 mile 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, technological advancements were made to ground processing systems, enhancing detection capability of smaller missiles to provide 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 in sensor design include above-the-horizon capability for full hemispheric coverage and improved resolution. Increased on-board signal-processing capability improves clutter rejection. Enhanced reliability and survivability improvements were also incorporated. The Space Based Infrared System is projected to 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 space-based early warning capability. The original DSP satellite weighed 2,000 pounds and had 400 watts of power, 2,000 detectors and a design life of 1.25 years. Throughout the life of the program, the satellite has undergone numerous improvements to enhance reliability and capability. The weight grew to 5,250 pounds, the power to 1,275 watts, the number of detectors increased three-fold to 6,000 and the design life has been increased to a goal of five years.
The 460th Space Wing, with headquarters at Buckley Air Force Base, Colo., has units that operate DSP satellites and report warning information, via communications links, to the North American Aerospace Defense Command/U.S. Northern Command and U.S. Strategic 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.
DSP satellites were typically 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). The final DSP satellite was launched on the new Evolved Expendable Launch Vehicle Delta IV, Heavy in November 2007.
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.
Primary mission: Strategic and tactical missile launch detection
Contractor team: Northrop-Grumman
Weight: 5,250 pounds (2,386 kilograms)
Orbit altitude: Approximately 22,300 miles (35,970 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: Sats 18-23
Unit Cost: $400 million
Operational Inventory: Classified