A 60-year ban on nuclear weapons in space has never been enforceable

When the United States and the Soviet Union signed the Outer Space Treaty in 1967, both nations agreed not to place nuclear weapons or other weapons of mass destruction in orbit around Earth. Nearly 60 years later, that prohibition has never had a working way to check whether anyone is actually following it. A recent feasibility study from an MIT physicist proposes a new detection method aimed at closing that gap, but experts who study space policy say the harder problem was never really the technology.

What The Outer Space Treaty Actually Bans

Article IV of the Outer Space Treaty was written to keep the Cold War’s nuclear arms race from extending into orbit, a goal both superpowers shared at the time. Under Article IV of the treaty, signatory states undertake not to place in orbit any objects carrying nuclear weapons or other weapons of mass destruction, install such weapons on celestial bodies, or station them in outer space in any other manner. What the treaty does not include is any inspection or verification regime. Neither Washington nor Moscow built in a mechanism for one side to confirm the other was complying, an omission that has persisted through every year since the treaty entered into force.

Why The Treaty Has No Way To Check Compliance

A warhead could, in theory, be built into an ordinary-looking satellite and operated in orbit for years with nothing externally visible to give it away. That gap has mostly stayed theoretical rather than urgent, in part because the world had already witnessed what a nuclear detonation in orbit does and largely avoided repeating it after the early 1960s. Even so, the absence of any verification tool means the ban has functioned more as a shared understanding among spacefaring nations than as an enforceable rule.

A New Detector Aims To Close That Gap

MIT physicist Areg Danagoulian’s feasibility study proposes a satellite-based sensor that would search for the physical signature of nuclear material aboard another spacecraft. The concept uses high-energy protons already trapped by Earth’s magnetic field as a probe: when those protons strike radioactive elements such as uranium inside a warhead, they are expected to produce a distinctive burst of neutrons. According to the study’s calculations, reported by Live Science, a detector roughly the size of an encyclopedia, fitted with specialized sensors, could pick up neutrons from a suspected warhead at a distance of about 2.5 miles after roughly a week of observation, with detection coming faster at closer range.

What A Nuclear Blast In Orbit Has Already Done

The risk the detector is meant to guard against is not hypothetical. On July 9, 1962, the United States detonated a 1.45-megaton warhead roughly 250 miles above the Pacific Ocean in a test known as Starfish Prime, one of a dozen high-altitude nuclear tests it conducted between 1958 and 1962. The blast knocked out radio communications for hours, produced artificial auroras visible from Hawaii, and damaged or destroyed eight of the 24 satellites in orbit at the time, including Telstar 1 and Britain’s Ariel 1. Radiation from the detonation lingered in orbit for roughly five years. On the ground, the electromagnetic pulse reportedly knocked out about 300 streetlights in Honolulu and set off burglar alarms across Oahu. The Soviet Union ran its own high-altitude tests, called Project K, in 1961 and 1962, which disrupted power and communications in what is now Kazakhstan. “It was one of the earliest instances where we began to have an understanding of the ways in which the space environment and the terrestrial environment are coupled together,” astronomer John Barentine, who has studied the environmental effects of Cold War-era space activity, told Live Science.

Why Detection Is Easier To Build Than To Deploy

Even if the sensor works as designed, using it would require flying a satellite close to another country’s spacecraft and holding that position for roughly a week, which raises problems well beyond engineering. “Satellite operators get really freaked out,” said Thomas González Roberts, an assistant professor at the Georgia Institute of Technology who studies how space powers engage with outer space governance. “If another satellite is spending too much time next to you, you might think that they’re spying on you.” Any workable inspection regime would also need the cooperation of the country whose satellite was being examined, along with new international norms for when such inspections could occur. “In my experience, the policy problems are always the bigger challenge than the technical problems,” said Brian Weeden, director of civil and commercial policy for the Center for Space Policy and Strategy at Aerospace Corp.

The Growing Stakes Of An Unverifiable Ban

Roberts argues that deliberate nuclear damage to satellites has stayed rare for a straightforward reason: any nation with the capability to destroy rivals’ satellites this way likely has a large orbital fleet of its own that would be damaged in the process. “There’s very few examples of nuclear damage in space because it’s so obviously a bad idea,” Roberts said. “These weapons are not really designed to be used, if you ask me.” He suggested the tactic would be more attractive to a state with little orbital infrastructure to lose, such as North Korea, than to a spacefaring power like Russia. That calculus has been tested by U.S. officials’ 2024 assertion that Russia was developing a nuclear anti-satellite weapon, a claim Moscow has denied. Officials pointed to Kosmos-2553, a Russian military radar satellite launched in 2022 into a radiation-heavy orbit that most communications spacecraft avoid; Russia said the mission was testing how onboard electronics handle radiation, while U.S. officials argued the radiation level there was not high enough to justify that explanation. The stakes of a repeat incident have grown sharply since the 1960s. In 1962, 24 satellites operated by two countries were in orbit; astronomer Jonathan McDowell’s tracker now counts more than 48,000 objects launched by upwards of 190 countries, most built with low-cost, off-the-shelf electronics that are not hardened against the radiation a nuclear detonation would produce. A federal government study cited by Live Science found that a single high-altitude blast could disable nearly all unhardened satellites in low Earth orbit within weeks to months, with direct financial damages approaching $500 billion and total economic impact potentially exceeding $3 trillion.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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