Half a Century of Warning Mission Ends
The US Space Force recently retired its last two Defense Support Program (DSP) missile-warning satellites, ending more than fifty years of service history. Since its first launch in 1970, the series used infrared sensors to detect missile launches during the Cold War, providing early warning of nuclear attack for the United States, and supported theater missile detection during the 1991 Gulf War, continuing to protect US forces from threats. According to Armscontrol.org, the retirement paves the way for deployment of a new generation of space infrastructure amid intensifying competition for space dominance.
Before retirement, the two satellites took part in a US Space Command exercise in early September and were then moved into a "graveyard orbit," the final orbit for decommissioned satellites to avoid posing a threat to satellites still in operation. Colonel Brandon Davenport, commander of the US Space Force's 4th Mission Detachment, said the retirement of the two satellites closes the book on half a century of space-based early-warning missions, which ensured deterrence during the Cold War and protected forces in combat after the Gulf War.
Current System Takes Over as Successor Faces Delays
After the DSP satellites' retirement, the US military's current primary warning system is the Space-Based Infrared System deployed since 2011. Through more advanced infrared sensors, the system provides improved missile-warning capabilities. Currently, the Space-Based Infrared System has four sensors hosted on highly elliptical orbit satellites, plus six satellites deployed in Earth synchronous orbit to take over the original warning mission.
However, the Space Force's transition in space warning capabilities still faces challenges. The next-generation Overhead Persistent Infrared satellites aim to further improve detection of small missile threats, but the originally planned launch date has been postponed, possibly as late as 2029. Contractor Lockheed Martin announced in August 2025 that the first next-generation Earth synchronous-orbit satellite had completed environmental testing. In addition, in the fiscal 2027 defense budget, the Space Force proposed terminating the polar satellite program in favor of low-orbit satellites, leaving the future US missile-warning architecture full of uncertainty.