The Defense Support Program (DSP) is a constellation of satellites in geosynchronous orbit (GEO) that detect the launch of strategic and tactical missiles, space launches, and nuclear detonations with infrared sensors that detect heat. DSP satellites are operated by the U.S. Air Force Space Command. Since the program’s first satellite launch in 1970, DSP has been a critical component of the North American Aerospace Defense Command’s (NORAD) Integrated Tactical Warning and Attack Assessment (ITW/AA) system.
DSP satellites provide the United States with a continuous space-based early warning capability. The satellites include a spinning sensor with short- and mid-wave infrared radars that have a 10-second revisit rate, though they are not dynamically taskable. The first DSP satellite that was launched in 1970 had a design life of a little over a year and weighed 2,000 pounds, had 400 watts of power, and included 2,000 detectors.
Satellites currently in operation have a design life of five years, weigh over 5,250 lb., have 1,275 watts of power provided by solar panels, and host 6,000 detectors each. 1 The satellites orbit in a geosynchronous trajectory 22,300 miles above earth’s surface. 2 The satellites have a height of 10m in orbit (8.5 m at launch) and a diameter of 6.7 m in orbit (4.2 m at launch). Each unit is estimated to cost around $400 million. 3 The satellites have been launched by Titan IIIC, Titan 34D, Titan IV, Titan IVB, Delta IV Heavy, and, on one occasion, a space shuttle. 4
Development, Testing, and Fielding
The USAF originally developed DSP satellites in response to the growing threat from Soviet and Chinese nuclear ballistic missiles during the 1960s. Between 1970 to 2007, the USAF launched 23 such satellites into orbit. 5 At the end of the Cold War, DSP satellites were retooled for additional tasks. During Operation Desert Storm in the early 1990s, for instance, DSP satellites were used to detect Iraqi Scud missile launches and helped provide early warning to civilians and coalition forces in the region. 6 The system’s infrared sensors have also been used to detect and assess volcanic activity and natural and manmade fires. 7
Information provided by the system is gathered and disseminated by the USAF 2d Space Warning Squadron, a unit within the 460th Operation Group located at Buckley AFB, Colorado, which has performed this role since 1992. 8 The U.S. military is working to replace the ageing DSP system with the Space-Based Infrared System-High (SBIRS-High), which will include technological advancements geared towards tracking 21st century missile threats. 9