Space Force Sunsets 1970s-Era Missile Warning Satellite Constellation

More than 50 years after the U.S. military launched its first Defense Support Program satellite, the Space Force has officially decommissioned the missile warning constellation as it prepares to start fielding its next-generation architecture. 

In a swan song of sorts, the last two remaining DSP spacecraft participated in a U.S. Space Command exercise in early September, helping the command demonstrate dynamic maneuvers across multiple orbits. Following the demonstration, the satellites were decommissioned into a supersynchronous—or graveyard—orbit, the Space Force’s Combat Forces Command said Oct. 1.

“These last two satellites were the culminating end to over a half-century of space-based early warning,” Mission Delta 4 Commander Col. Brandon Davenport said in a statement. “The DSP constellation ensured deterrence during the Cold War and protected our deployed warfighters from the Gulf War until their retirement last month.”

The first DSP satellite was launched in 1970 to geosynchronous orbit, providing key ballistic missile warning capabilities amid Cold War tensions between the U.S. and the Soviet Union. The goal was to discourage a first strike from the Soviets and help stabilize the relationship between the two nuclear-armed states. As the U.S. built out the constellation, it was used to detect theater missile launches in Iraq during the Operation Desert Storm in 1991. Its infrared sensors have also been used to detect natural disasters like forest fires and volcanic eruptions. 

The constellation eventually grew to 23 satellites, the last of which launched in 2007. However, the service life of that final spacecraft was cut short in 2008 when a component failure caused it to drift to an unintended orbit. The Defense Department had originally set out to launch a 24th satellite, but ultimately canceled that plan. A full-sized DSP test article is on display at the National Museum of the United States Air Force in Dayton, Ohio. 

DSP’s immediate successor, the Space-Based Infrared System, is on orbit today and consists of six satellites in GEO as well as four in a highly elliptical orbit. The Space Force is on the verge of launching the first of two Next-Generation Overhead Persistent Infrared satellites in the coming months. The spacecraft will augment the SBIRS constellation with improved, more sensitive sensors to detect dimmer threats.

Those two Next-Gen OPIR satellites, going to geosynchronous orbit, are part of the Space Force’s plan for a multiorbit missile warning architecture, which will include proliferated constellations in medium-Earth orbit and low-Earth orbit developed by Space Systems Command and the Space Development Agency, respectively. The service also had plans to fly two Next-Gen OPIR Polar satellites, but proposed canceling the program in its fiscal 2027 budget request. House and Senate lawmakers have supported maintaining the effort in drafts of defense spending and policy legislation, but its future will remain undecided until a final appropriations bill passes both chambers. 

In its press release, Combat Forces Command noted that sunsetting the last two DSP satellites will allow operators in the 2nd Space Warning Squadron to shift their focus toward preparing for launch and initial testing of the first Next-Gen OPIR satellites.

“Retiring our legacy DSP system allows us to best posture for the future,” said Lt. Col. Ann Hughes, the squadron commander. “Our crews are always ready on each and every system they operate to ensure seamless [missile warning and tracking]. Onboarding future systems requires training for every scenario from unforeseen software issues to countering adversary aggression on orbit. We’re focused on providing a reliable, consistent, and seamless picture of missile threats regardless of the operational environment.”