America’s Cold War missile-warning constellation went out with a workout. In September, during US Space Command’s Apollo Maneuvers 2026 live-fly exercise, Guardians of the 2nd Space Warning Squadron put the last two Defense Support Program (DSP) satellites through dynamic on-orbit maneuvers. Then they sent them up into a supersynchronous graveyard orbit for good.

The Space Force’s Combat Forces Command announced the retirement on 1 October 2026, closing a program that launched 23 satellites. The first lifted off from Cape Canaveral on a Titan IIIC on 6 November 1970. In between, DSP kept watch on Soviet missile fields during the Cold War and gave the first warnings of Iraq’s Scud attacks in 1991.

Mission Delta 4 now carries on with DSP’s successor, the Space Based Infrared System (SBIRS), while it prepares for the first Next-Generation Overhead Persistent Infrared (Next-Gen OPIR) satellite. For air and missile defenders the currency is time: looking down from 22,300 miles, an infrared sensor can catch a missile’s exhaust as it leaves the launcher, adding warning that ground radars alone cannot give.

One last workout, then the graveyard

Combat Forces Command said the squadron’s on-orbit work includes dynamic maneuvers in a contested environment, the scenario Apollo Maneuvers 2026 simulated. According to Air & Space Forces Magazine, the DSP pair helped Space Command demonstrate dynamic maneuvers across multiple orbits in early September before they were retired.

The 2nd Space Warning Squadron belongs to Mission Delta 4 at Buckley Space Force Base, Colorado, which provides strategic and theater missile warning. Mission Delta 4’s commander, Col. Brandon Davenport, called DSP “foundational to the defense of our nation.”

Lt. Col. Ann Hughes, who commands the squadron, said retiring the legacy system “allows us to best posture for the future.” Her crews have begun training to take on the first Next-Gen OPIR satellite in geosynchronous orbit, starting with its launch and early orbit testing.

From a stranded first flight to the Shuttle

DSP’s debut was rocky. The Titan IIIC’s Transtage upper stage misfired, leaving Flight 1 in an orbit of 26,050 by 35,886 kilometers rather than a geosynchronous one. It never became operational, but the Air Force used it to test the sensor against American missile launches, space historian Dwayne Day has written.

The satellites kept growing. The first weighed 2,000 pounds and carried 2,000 infrared detectors; later models grew to 5,250 pounds and 6,000 detectors. Most rode Titan boosters. Only one went up on a Space Shuttle: DSP-16, carried in Atlantis’s payload bay on STS-44, launched on 24 November 1991.

Each satellite spun six times a minute, sweeping an off-axis infrared telescope across the Earth for the heat of rocket plumes. In the 1960s, planners reckoned such a satellite could stretch warning of an ICBM attack from the roughly 15 minutes radars gave to as much as 27, Day writes. DSP also watched for space launches and nuclear detonations.

The 23rd and last DSP lifted off from Cape Canaveral on 10 November 2007 on the first Delta IV Heavy to carry an operational satellite. It failed in 2008 and drifted out of its intended orbit, but its launch drew a fitting tribute from the 45th Space Wing’s commander.

Desert Storm made it famous

DSP was built to catch Soviet ICBMs. For the 1991 Gulf War its sensors’ sensitivity was raised to pick up Iraq’s cooler Scuds, which caused false alarms early on that were fixed by the war’s end, according to Day. The satellites detected the Scud launches and gave warning to civilians and coalition forces in Israel and Saudi Arabia.

Getting that warning to the shooters was improvised. US Space Command received the satellite data at Cheyenne Mountain, Colorado, and a link to the Army’s Patriot batteries had to be cobbled together during the war, Air Force Magazine reported in 1996. DSP could not pinpoint launch areas, the magazine noted in 2001, so the hunt fell to crews such as the F-15E Strike Eagle squadrons flying the nightly “Scud Patrol” over western Iraq.

The lessons stuck. Ground-processing upgrades in 1995 improved DSP’s detection of smaller, short-range missiles. Air & Space Forces Magazine credits DSP and SBIRS together with early detection of Iran’s January 2020 ballistic missile strike on US forces at Al Asad Air Base, Iraq. The sensors also spotted forest fires and volcanic eruptions.

A 2022 US Space Force video on Space Delta 4, now Mission Delta 4, the Buckley-based unit that provides strategic and theater missile warning with infrared satellites and ground-based radars.

SBIRS holds the line

DSP’s successor is already on watch. SBIRS launched its first geosynchronous satellite in May 2011 and its sixth and final one in August 2022, and it adds four infrared payloads riding host satellites in highly elliptical orbits to cover the polar regions.

Next comes Next-Gen OPIR. The first of two geosynchronous satellites, once due in fiscal 2025, slipped over payload problems and is expected to launch in the coming months, Air & Space Forces Magazine reports. The Space Force has proposed canceling the program’s two polar satellites in its fiscal 2027 budget, citing coverage from new low- and medium-Earth-orbit constellations, but lawmakers have backed keeping them. Missile-warning satellites are central to the Trump administration’s Golden Dome missile-defense project.

DSP kept watch for more than half a century, not bad for a satellite family whose original design life was 15 months. Anyone who wants to see one up close can visit the full-size DSP test article on display at the National Museum of the United States Air Force in Dayton, Ohio.

Sources: US Space Force Combat Forces Command, 1 October 2026; Air & Space Forces Magazine, 1 October 2026; SpaceNews, 1 October 2026; US Space Force DSP fact sheet (October 2020) and SBIRS fact sheet (March 2023); 45th Space Wing Public Affairs, 13 November 2007; U.S. Strategic Command, 11 August 2022; The Space Review (Dwayne A. Day), 22 August 2022 and 27 May 2025; Air Force Magazine, June 1991, February 1996 and July 2001; Air & Space Forces Magazine, 29 April, 19 May and 18 June 2026; GlobalSecurity.org; NASA Image and Video Library; Wikipedia