Nuclear physicist Areg Danagoulian of MIT proposed a technique to identify nuclear weapons in space, publishing his findings on July 8, 2026, in the journal Nature. The proposed method utilizes a shoebox-sized satellite designed to detect neutrons, offering an approach to verifying compliance with the Outer Space Treaty.

The Outer Space Treaty has prohibited nuclear weapons in space since 1967 and has been ratified by 118 countries, including Russia and the United States. Danagoulian's technique involves outfitting a small satellite with detectors to spot neutrons originating from a target satellite when high-energy protons interact with a nuclear weapon's uranium. Simulations suggest an inspecting satellite could identify a thermonuclear weapon from 4 kilometers away after about a week of shadowing. This measurement could be shortened to hours with a closer approach or the use of multiple inspector satellites.

The United States has claimed that Russia is developing a space-based nuclear weapon, with allegations that Russia's Cosmos 2553 satellite, launched in February 2022, is a test for a potential future orbital weapon. Russia has denied these allegations. The Cosmos 2553 passes through the inner Van Allen belt, an area Danagoulian described as problematic for satellites due to radiation exposure. "That's a terrible place to put a satellite at. You're going to damage your satellite with all that radiation," Danagoulian said.

Astrodynamicist Thomas González Roberts of Georgia Tech acknowledged the work's potential. "There's a lot in this work that's really interesting and exciting," Roberts said. However, he also noted practical challenges. Roberts stated that for detection, "the satellite that has this detection device would need to maneuver to be near, very, very near" to the target satellite. Satellites approaching within tens of kilometers have previously caused concern among operators, and proximity between satellites without coordination could increase the risk of collision.

Political scientist Victoria Samson of the Secure World Foundation emphasized the importance of verification. "It is really important to have verification mechanisms," Samson said. "It's not just a matter of, 'We're asking you not to do this,' it's like, 'We can tell if you have something up there,'" she added. Roberts suggested that Danagoulian's idea would function most effectively as part of a formal verification scheme integrated into a treaty.

Why It Matters

This proposed technique addresses the challenge of verifying compliance with the 1967 Outer Space Treaty, which prohibits nuclear weapons in orbit and has been ratified by major spacefaring nations including Russia and the U.S. Following U.S. claims regarding a potential Russian space-based nuclear weapon, the ability to independently detect such devices could provide a new verification tool. The method could facilitate stronger international arms control agreements by offering a means to confirm adherence to treaties, potentially mitigating risks of weaponization in outer space.