Inside the $35 Billion Plan to Track Hypersonic Missiles from Space

OPINION — “The Department of Defense’s Space Development Agency (SDA) is developing a new space-based architecture comprised of a large constellation of at least 300-500 satellites in low Earth orbit (LEO) to detect and track potential missile threats. This system will complement other space systems currently providing this capability. SDA is developing this new system in part in response to peer and near-peer competitors that are designing strategic and tactical hypersonic weapons that are not easily detected, identified, or tracked by current space-based missile warning systems.”That’s a quote from a Government Accountability Office (GAO) report sent to Congress last Wednesday entitled MISSILE WARNING SATELLITES, Space Development Agency Should Be More Realistic and Transparent About Risks to Capability Delivery.I’ve chosen to write about this report because it contains not only the best description of how complicated and costly just one aspect of missile defense has become, but also it provides the most understandable history of what’s been done up to now, along with the threats we face.Known within the Defense Department (DoD) as the Proliferated Warfighter Space Architecture (PWSA) – and started in 2020 — the plan, according to the GAO report, is “intended to provide space surveillance and communications for persistent, timely, global awareness [of missile threats] that is designed to operate in an increasingly contested space environment.”DoD so far has committed nearly $11 billion to this effort, which is programmed to cost near $35 billion through fiscal year 2029.While the PWSA deals with tracking an already launched missile and its warhead, there are two other elements of a missile warning system: Detecting the launch and communicating information within elements of the system.Traditionally, missile threats have been detected and tracked because they are launched using powerful rocket boosters which produce heat and light making them easy to initially see and follow and predict their ballistic trajectories. Infrared sensors on space satellites can detect heat from launched missiles and booster plumes against Earth’s backgroundIn 1970, DoD put in place the first Defense Support Program satellites, which used infrared sensors. These first satellites with infrared sensors, and the infrared systems that have followed, have operated from geosynchronous Earth orbits (GEO), which allow those satellites to stay fixed over a single, longitudinal spot located about 22,000 miles above Earth. This results in each GEO satellite maintaining constant observation of a specific area of the globe and collectively monitoring the entire planet.In the mid-1990s, DoD developed the Space Based Infrared System (SBIRS) to replace and provide significantly more robust data than the Defense Support Program.Wednesday’s GAO report said, “In recent years, DoD has identified emerging threats that these [SBIRS] systems may be unable to effectively warn or defend against. For example, Russia and China have successfully demonstrated hypersonic missile capabilities. In addition to new missile threats posed by potential adversaries, DoD has also publicly acknowledged emerging threats to our space assets. For example, DoD reported that China is developing additional counterspace capabilities including directed energy weapons, electronic warfare, and other anti-satellite weapons.”According to the GAO, “U.S. missile warning satellites currently operating in GEO may be particularly vulnerable to these emerging threats because there are relatively few of them — making them high-value targets — and their location above Earth is effectively stationary and predictable.”Approximately three DSP satellites of the original 23 DSP system remain in orbit with one maybe still operational. In addition, beginning in 2011 there have been six SBIR satellites put in orbit and SBIRS sensors placed on four additional host satellites.The GAO report said, “SBIRS will soon be followed by the Next Generation Overhead Persistent Infrared (Next Gen OPIR) system, designed as an upgraded replacement for SBIRS, with sensors that are expected to have even greater sensitivity than current SBIRS sensors. While providing some enhanced capabilities, such as greater sensitivity, the Next Gen OPIR system is built around an architecture similar to existing systems now in GEO orbit.DoD is also developing space-based laser communications technology to support large constellations of satellites for missions, including missile warning and data transport. However, a February 2025 GAO report found that DoD had “made progress in developing this technology, but it also faced delays and other issues — and hasn’t fully demonstrated that it works in space. Despite these challenges, DOD plans to continue to develop and launch hundreds of satellites worth billions of dollars that require the use of laser communications.”DoD’s plan for the new PWSA missile satellites in LEO, internally referred to as the Tracking Layer, will complement the Next Gen OPIR satellites for what is termed missile warning/missile tracking (MW/MT) functions, and will use laser technology to communicate.Because satellites in LEO are much closer to Earth than those in GEO, many more satellites are needed in a LEO-based constellation to achieve the same coverage as a single one in GEO.The missile tracking satellites in LEO are traveling much faster relative to Earth’s surface and therefore each satellite can only observe a small section of Earth’s surface for a short time — only about 10 minutes. This makes constellation development more complicated if constant global coverage is required.“Some DoD officials say having a greater number of satellites performing MW/MT in LEO will result in greater resiliency for the constellation as a whole and the capability it provides,” the GAO report says, adding, “For example, if one satellite in a proliferated constellation is damaged — whether intentionally or by natural environmental effects — the constellation’s capability is degraded by a smaller margin than if the entire constellation was made up of only a handful of satellites.”The current plan has been to develop a large constellation of tracking satellites in LEO, along with data transport layer satellites forming a communications network to provide mission data directly that will enable advanced missile tracking from LEO to ground stations.A tracking satellite, according to the GAO report, is “comprised of a spacecraft – referred to as a bus — plus other components such as infrared sensors, on-board mission data processors, and communication payloads, together with a ground segment to manage the constellation and receive and process track data to send to the wider DoD and intelligence community.”There will be some 600 satellites in all, with plans then to replenish each tranche every two years in perpetuity, along with associated ground systems, according to the GAO report. As the LEO-orbiting tracking satellites approach the end of their life, “SDA will deorbit them,” the report says.SDA has been acquiring tranches of both tracking and data transport layer satellites beginning with a demonstration tranche, called Tranche 0 (T0) that was launched in April 2023. Of the 27 satellites in T0, 19 performed data transport and communications, while eight did missile warning. One additional satellite remained on the ground as a test bed. Tranche 0 was designed to be a “warfighter immersion” tranche, giving service members the opportunity to work with the systems, understand their capabilities, and to develop operational concepts for their use.An SDA official told the GAO T0 demonstrated “the ability to track a short-range ballistic missile throughout its flight and into its terminal phase and then transmit raw data to the ground from space.” It also connected the tactical data link network used by NATO, from space to specific ships and military airplanes and established the first satellite-to-satellite demonstration of optical links between two of the four T0 contractors.In September 2025, Tranche 1 of the PWSA program, put 21 tracking satellites into orbit, followed the next month by another 21 data transport layer satellites. Overall, Tranche 1 is scheduled to consist of 128 satellites for the Transport Layer and 26 for the Tracking Layer.SDA said back in October 2025, “Beginning in 2027, T1 will provide an initial warfighting capability through the PWSA to deliver regional persistence for tactical military data channels…along with advanced missile tracking and missile warning, and beyond-line-of-sight targeting.”Wednesday’s GAO report said, “According to SDA, T1 will establish the PWSA ground and operations baseline, or the foundation upon which SDA plans to add capabilities in future tranches. To reduce risk, SDA is taking an incremental approach to delivering these ground operations.”However the next T1 satellite launches have been delayed to sometime this year.Wednesday’s GAO report raised significant issues in the ongoing PWSA program.For example, it said, “SDA had planned to allow the warfighter to provide feedback on capabilities prior to a larger SDA investment in T1 and future tranches, but officials from combatant commands we spoke to told us that they have not been asked to provide feedback on T0 MW/MT demonstrations.”In a broader sense, the GAO said, “SDA has not taken steps to understand the range of risks to delivering MW/MT capabilities by assessing the technological maturity — such as by conducting a technology readiness assessment — of critical technology elements included in its satellite development given required modifications and use in new environments. Absent such assessments, SDA remains overly reliant on technology maturity estimates provided by contractors and lacks key insights to better develop realistic development timelines.”In short, as with many needed highly-technical and complex defense systems, this new space-based, large constellation of satellites in low Earth orbit to detect and track potential missile threats appears to be developing higher costs and a delay before it is fully operational.The Cipher Brief is committed to publishing a range of perspectives on national security issues submitted by deeply experienced national security professionals. Opinions expressed are those of the author and do not represent the views or opinions of The Cipher Brief.Have a perspective to share based on your experience in the national security field? Send it to [email protected] for publication consideration.Read more expert-driven national security insights, perspective and analysis in The Cipher Brief

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