The United States has launched the final satellite payload for its current-generation Global Burst Detection system, a critical space-based network designed to identify nuclear detonations anywhere on Earth. This milestone, achieved in May 2025, marks a transition as national laboratories are already delivering hardware for a more advanced system scheduled for its first launch in 2027.
Developed and maintained by Sandia and Los Alamos national laboratories for over 60 years, the system operates from a constellation of GPS satellites orbiting approximately 12,550 miles above the planet. The ongoing mission ensures the U.S. maintains an uninterrupted capability to monitor for nuclear events from space.
Key Takeaways
- The final Global Burst Detector of the current IIIA series was launched in May 2025.
- This system is a payload on GPS satellites and detects signals from nuclear detonations.
- Development of the next-generation IIIF series is complete, with the first launch planned for 2027.
- The new IIIF system features an advanced optical sensor capable of capturing tens of thousands of frames per second to improve accuracy.
- The mission is a long-standing collaboration between Sandia and Los Alamos national laboratories, funded by the NNSA.
A 60-Year Vigil From Space
For more than six decades, the United States has maintained a space-based system dedicated to detecting nuclear detonations. Known as the Global Burst Detection (GBD) system, this network is a key component of the broader U.S. Nuclear Detonation Detection System. Its primary function is to provide real-time information to the U.S. government and military if a nuclear event occurs above ground.
The GBD payloads are hosted on U.S. global positioning satellites, forming a constellation that provides continuous global coverage. Teams of scientists and engineers at Sandia and Los Alamos work on a decade-long timeline to design, build, and test these complex instruments, ensuring they can counter emerging threats and operate reliably in the harsh environment of space.
"The launch of the final IIIA series Global Burst Detector marks an important milestone in our efforts to enhance nuclear detection capabilities," said Sandia manager Andrew Stuart. "The collaboration between Sandia National Laboratories and Los Alamos National Laboratory has been key to developing this advanced system."
How the System Works
The GBD system is equipped with a suite of sensors that detect specific signatures of a nuclear detonation. These include optical signals (the flash of light), X-rays, and electromagnetic pulse energy. By recording these signals and their timing, the system allows the U.S. Air Force to precisely calculate the location, time, and estimated yield of a detonation.
Transitioning to the Next Generation
The launch on May 30, 2025, from Cape Canaveral carried the last payload of the current block, known as the IIIA series. Following the launch, teams from Sandia, Los Alamos, and the U.S. Space Force spent June calibrating the new system and conducting on-orbit tests to confirm its functionality. The final step involves integrating its data into the existing satellite network.
Even as the final IIIA system became operational, the next generation was already being prepared. In 2024, the national labs delivered the first two flight systems for the new IIIF series to Lockheed Martin. These units are now ready for integration onto new GPS satellites.
15+ Years: Each Global Burst Detector payload is designed and rigorously tested to operate reliably for a mission lasting more than 15 years in orbit.
Marc Kippen, a program manager at Los Alamos, noted the significance of this continuity. "The May launch is a testament to the decades of effort that it takes to maintain uninterrupted national security space capability," he stated. The first launch of a GPS satellite carrying a IIIF payload is scheduled for 2027.
Advanced Sensor Technology Improves Accuracy
The development of the IIIF series, a project that took 12 years of collaboration between the two labs, introduces significant technological advancements. A key innovation is the Spectral Imaging Geolocation Hyper-Temporal Sensor, or SIGHTS. This new optical sensor is designed to be much more effective at distinguishing between a true nuclear event and other phenomena that might produce a bright flash, such as lightning or reflections.
The foundation for SIGHTS was laid more than a decade ago through Sandia's Laboratory Directed Research and Development program. This internal research initiative focused on pushing the limits of remote sensing technology, which ultimately led to the creation of a new megapixel-density optical sensor.
Capturing Events in High-Speed Detail
What makes the SIGHTS sensor unique is its incredible speed. It is capable of capturing tens of thousands of frames per second. This high frame rate provides a detailed, slow-motion view of a light event, allowing the system's software to analyze the signature and better differentiate between legitimate signals and potential false positives.
This enhanced capability is crucial for maintaining the reliability of the detection network. Before any payload is sent to space, it undergoes an extensive series of qualification tests at Sandia. These tests simulate the extreme conditions of a rocket launch and space operations, including:
- Vibration and shock tests
- Thermal and thermal vacuum tests
- Prompt X-ray exposure tests
These processes, funded by the National Nuclear Security Administration (NNSA), ensure each system can survive its journey into orbit and perform its critical mission. Over the next decade, Sandia and Los Alamos will continue to deliver more IIIF systems for integration and launch, continuing a vital national security mission for the foreseeable future.