The origins and evolution of the Defense Support Program (part 4): DSP forever?by Dwayne A. Day
|
| At the start of the decade when DSP was supposed to finally be replaced, all three components of the SBIRS program were delayed, and budgets were increasing. |
By 1996, the Air Force had signed a contract to develop the Space Based Infrared System-High, or SBIRS-High, planning for first launch in 2002 and the goal of completely replacing DSP with a much more capable system by 2010.[1] Things did not go to plan, and surprisingly, DSP remains operational even today, over two decades after the last operational satellite was launched. (See “The origins and evolution of the Defense Support Program (part 1): Infrared for missile warning”, The Space Review, August 22, 2022; “The origins and evolution of the Defense Support Program (part 2): DSP gets an upgrade,” September 6, 2022; and “The origins and evolution of the Defense Support Program (part 3): The hangar queens and DSP-1,” May 27, 2025.)
 California governor Arnold Schwarzenegger during a visit to the DSP manufacturer. A satellite infrared sensor platform is in the background. (credit: Northrop Grumman) |
During the 1990s, the operational DSP stations were 37 degrees west (Atlantic), 10 degrees east (European), 69 degrees east (East or Indian) and 152 degrees west (Pacific). The backup station was 110 degrees east (East Indian). Which ground facilities controlled specific satellites is not totally clear, but the Buckley, Colorado, and Nurrungar, Australia, stations probably handled two each and the European ground station only one, although the European station may not have directly controlled the satellite, only relayed commands and data. Standard procedure during the ’90s was apparently to launch the newest satellite to replace the oldest in the operational constellation. The oldest was then shifted to the backup position over the East Indian Ocean, and the satellite it replaced was discarded, boosted to a graveyard orbit.
By 1996, satellites 19, 20, 21, and 22 were all in storage, while number 23 was building. DSP 18 was launched on February 23, 1997, and there is some indication that this satellite was upgraded from the earlier versions and part of “Block 18.” DSP 19 was launched on April 9, 1999, but a failure of the Titan IV resulted in the satellite not reaching orbit. Because the Air Force had decided against building satellites 24 and 25, and had also signed a contract for DSP’s replacement, that meant that those remaining four DSP satellites were of increasing importance.
Partly in anticipation of the new system, as well as a desire to further reduce costs, on October 12, 1999, the Overseas Ground Station—the Joint Defence Facility, Nurrungar—closed. The Relay Ground Station-Pacific, located at Pine Gap, Australia, served as a “bent pipe,” relaying data from the DSP satellites back to the Continental Ground Station at Buckley Air Force Base in Colorado, which controlled the satellite. Nurrungar had long been vulnerable to changes in US-Australian relations, and shutting it down removed one potential vulnerability to the United States’ missile warning network, although Pine Gap remained another weak link, and many years later gathered unwelcome attention as the subject of an Australian television series.
A similar consolidation took place on the other side of the globe when the European Ground Station in Kapaun, Germany, closed at the end of September, and Menwith Hill in England began serving as the European Relay Station for the European DSP satellite. Buckley’s DSP station was also being replaced by the new SBIRS Mission Control Station, also at Buckley. By June 2001 it assumed control of DSP satellites and was fully operational by September, several years before the planned debut of the SBIRS satellites.[2]
In 1999 there was increased concern within the US military about the impending end of the millennium, and what became known colloquially as “Y2K.” Many civilian and military computer systems had software that was not designed for the new year ending in “00,” and coders around the world furiously sought to update and patch software systems so that they would not crash. The US military even took the extraordinary action of inviting a Russian military delegation to attend the specially created Y2K data center at Peterson Air Force Base, Colorado, over the new year to monitor data flowing from American radar sites and satellites from around the world, including the time, position, and trajectory of any missile launched anywhere in the world. This was intended as insurance in case any Y2K software bugs indicated a missile launch was underway.[3]
 The last DSP satellites were built in the late 1990s and early 2000s. Here one is being lifted. Note the solar panels folded up around the satellite bus. (credit: Northrop Grumman) |
By the early 2000s, the SBIRS program was in trouble. The plan had been for a SBIRS-High constellation with satellites in geosynchronous orbit, augmented by sensors in highly elliptical orbit, followed by a 24-satellite constellation of SBIRS-Low satellites in low Earth orbit. SBIRS-High and SBIRS-HEO would make the first detections of launches, and SBIRS-Low satellites would provide more precise tracking to enable interception of missile warheads. But the Air Force began experiencing problems, setbacks, and cost overruns in all three programs.
| The Air Force certainly developed contingency plans in case a satellite degraded or failed entirely, but they never expected that DSP would have to shoulder the burden of missile warning for an additional decade. |
The first flight of a SBIRS-High satellite was delayed from 2002 to 2004, with the goal of having the constellation of four geosynchronous satellites in place by 2008.[4] In 2001, technical issues with the infrared payload for the highly elliptical satellites also delayed their deployment. SBIRS-Low was supposed to launch its first satellite by 2006 and its tenth by 2010, but that program also ran into numerous delays, and its cost ballooned to $23 billion.[5] At the start of the decade when DSP was supposed to finally be replaced, all three components of the SBIRS program were delayed, and budgets were increasing.
Over the next few years, SBIRS-High continued to suffer major development problems, resulting in a launch slip from September 2004 to October 2006, and soon its costs had increased from the original $2.1 billion estimate to over $8 billion, and then to $9.9 billion.[6] In the 1980s and 1990s, the Air Force’s Milstar communications satellite program had been the poster child for military space procurement’s woes. Now it was replaced by SBIRS—until SBIRS was eventually supplanted by another program plagued by cost overruns and schedule delays.
In 2006 the first SBIRS-HEO payload was finally launched, followed by the second in 2008 (with two more launched in 2014 and 2017.) Although these payloads replaced DSP-Augmentation payloads, not DSP satellites in geosynchronous orbit, they provided additional infrared warning and tracking capability, alleviating some concerns about the aging DSP constellation.
It was not until May 2011 when the first SBIRS-High satellite finally launched, nine years after the original plan.[7] Throughout these extended delays, DSP and DSP-Augmentation (infrared sensors carried on classified payloads in highly elliptical orbits) served as the in-space missile warning systems. The Air Force certainly developed contingency plans in case a satellite degraded or failed entirely, but they never expected that DSP would have to shoulder the burden of missile warning for an additional decade.
 A DSP satellite with one of its four solar panels in deployed position. The infrared telescope has not yet been installed on top of the satellite. (credit: Northrop Grumman) |
DSP 20 was launched on May 8, 2000, apparently becoming the Pacific satellite. DSP 21 was launched on August 6, 2001, becoming the eastern hemisphere satellite.[8] DSP 22, nicknamed “Eagle Eye,” was launched on February 14, 2004.[9]
The final DSP satellite, number 23, was originally scheduled for launch in August 2005 atop the new Delta IV rocket. However, a test of the Delta IV in December 2004 was not fully successful. This and other issues prompted the DSP launch to be pushed back to April 2007. But in March of that year the fueling test of the rocket did not go as planned, and the launch was further pushed back to the summer, and then even further.
Although DSP Flight 23’s launch delays were due to problems with the rocket, the delay may have also been intended to alleviate the major delays in launching SBIRS-High by extending the overall lifetime of the DSP constellation.[10]
DSP Flight 23 was finally launched on November 11, 2007 from Florida.[11] Although the Air Force had sought to be extra careful with the launch of its last DSP, this satellite failed less than a year after launch. No clear reason for the failure was ever made public. (See “The ongoing saga of DSP Flight 23,” The Space Review, January 19, 2009.)
A 24th satellite had been canceled. A full-size, structural test article was donated to the National Museum of the United States Air Force in 2010 and became part of a new display there in 2020.
In 2011, the first SBIRS-High satellite was launched, followed by the second in 2013, the third in 2017, and the fourth in 2018. The standard DSP constellation was three primary satellites, meaning that DSP would have been required to operate at least one satellite until approximately 2018 when SBIRS-High was fully operational. SBIRS-High 5 and 6 were launched in 2021 and 2022 respectively.
 A DSP satellite during a ground test. As of May 2025, three of these satellites are still operational, over two decades after launch. Their condition is classified, but they must serve some national security function. (credit: Northrop Grumman) |
It is not known what the Air Force’s plans for retiring the DSP program were as the service prepared to launch the last satellites in the 2000s. The DSP-1, or “Block 14,” satellites that entered service in 1989 were designed with a three-year minimum lifetime and a five-year goal. But an older satellite was retired in 1994 after ten years in service, indicating that the satellites were capable of significantly longer lifetimes.
The last three DSP satellites to become operational were launched in 2000, 2001, and 2004 and, if they had nominal five- to ten-year lifetimes, they would have been retired probably around ten years after launch, and certainly after the replacement SBIRS satellites had become operational. Surprisingly, as of 2025 there are indications that those three DSP satellites remain operational. That may be due not only to the lateness of the SBRIS-High program, but also to a geopolitical change.
In January 2007, China launched an anti-satellite weapon against one of its own satellites, generating substantial debris in low Earth orbit and causing significant controversy around the world. This may have prompted the Air Force to realize that constellations consisting of few satellites in geostationary orbit were potentially vulnerable. A relatively easy risk mitigation was to keep the DSP satellites operational instead of just replacing them by the new SBIRS satellites, assuming that they still retained some capability. At the very least, they increased the number of satellites that an adversary would have to target.[12]
| DSP has a sophisticated infrared sensor that is the key to its entire mission and the sensor had been one of the primary lifetime limiters for the satellites—the Air Force apparently found a way to dramatically increase the lifetime of the sensor. |
In 2010, an Air Force official stated that the service had no plans to retire the DSP program. “The DSP program is in really good shape and we have no desire to take any of those systems offline as SBIRS comes into being,” said Colonel Chance Saltzman, 460th Operations Group commander at Buckley AFB, Colorado. Saltzman indicated that the Air Force was taking a long-term approach towards maintaining the satellites. “We are looking sub-system by sub-system and satellite by satellite to see if there are tactics we can employ to wring the most out of those satellites… We’re looking at all options,” he said.[13]
By the mid-2010s, the Air Force had consolidated the ground segments for DSP and SBIRS HEO/GEO to a single site. Starting in fiscal year 2018, all Air Force "Missile Warning/Attack Assessment" activities were consolidated under the SBIRS moniker.[14]
In June 2020, the US Defense Department awarded a $222.5 million life extension contract for DSP. Contracted work will continue up to March 31, 2030.[15]
"Northrop Grumman Systems Corp., Azusa, California, has been awarded a $222,507,873 cost-plus-fixed-fee contract for the Defense Support Program (DSP) Operations, Mission Threat Analysis and Engineering Sustainment (DOMES). This contract provides on-orbit satellite and anomaly resolution support, root cause analysis, mission threat analysis, mission test bed and space awareness and global exploitation as key components of the lifetime extension of the DSP. Work will be performed in Azusa, California; Redondo Beach, California; Aurora, Colorado; and Colorado Springs, Colorado, and is expected to be completed March 31, 2030. Fiscal 2020 operations and maintenance funds in the amount of $18,000,000 is being obligated at the time of award. Space and Missile Systems Center, Peterson Air Force Base, Colorado, is the contracting activity."
The Air Force’s Fiscal Year 2025 budget request, produced in February 2024, stated of the DSP program: "These ground-based systems work in conjunction with the space-based missile warning system, the Space-Based Infrared Systems (SBIRS), to provide assured missile warning. SBIRS currently employs Defense Support Program satellites to detect and track missiles through observation and processing of infrared energy emitted during the missile boost phase."[17]
Other sources in 2024 still referred to DSP, indicating that it remained operational in some capacity: “In 2011, the Space Force began deploying the Space-Based Infrared System (SBIRS), a series of satellites and ground systems to detect and track the launch of adversary missiles. SBIRS satellites operate in geosynchronous (GEO) and highly elliptical orbits to observe missile launches worldwide. SBIRS is DOD’s replacement of the 1970s Defense Support Program satellites.”
An undated photo surfaced in late 2024 showing an American general giving a talk at a meeting, accompanied by a slide that showed operational Space Force programs. A DSP satellite was included in the slide, along with several other programs that had similar legacies, such as Milstar and the Defense Support Communications System (DSCS). Communications satellites have demonstrated very long lives in geostationary orbit, but DSP has a sophisticated infrared sensor that is the key to its entire mission and the sensor had been one of the primary lifetime limiters for the satellites—the Air Force apparently found a way to dramatically increase the lifetime of the sensor.
At least three DSP satellites were still in operation in May 2025, fifty years after the first launch:
The Space Force is now planning for new infrared warning and tracking systems to replace SBIRS, adopting a different approach that would distribute many more sensors in different orbits and moving away from a few large, expensive satellites in geosynchronous orbit. The history of SBIRS and its delays and cost overruns certainly haunts the architects of this new approach. To date, the Space Force has not announced the formal retirement of the DSP program, however, the youngest satellite was launched over 20 years ago. DSP won’t last forever, but it has been proven to be a tough bird.
Next: Replacing DSP.
Note: we are now moderating comments. There will be a delay in posting comments and no guarantee that all submitted comments will be posted.
