Neutrons emitted by a bomb could reveal its presence 4 kilometers away
Space is supposed to be free of nuclear weapons, but there is no way to verify this. A recently proposed technique could search for illicit nuclear weapons in orbit.
Since 1967, nuclear weapons in space have been banned by the Outer Space Treatywhich has been ratified by 118 countries, including Russia and the United States.
Now, MIT nuclear physicist Areg Danagoulian has developed a plan to identify nuclear rule breakers in space. A satellite the size of a shoebox could come closer to a suspicious satellite. If a nuclear weapon were on board the spacecraft being scanned, the inspector would detect neutrons produced when nearby high-energy protons crashed into the weapon, Danagoulian reported on July 8 to Nature.
A nuclear weapon, if detonated in orbit, would wipe out a large number of satellites – a possibility that has become more worrying in recent years as the number of satellites has increased enormously and people have become dependent on the data they transmit.
In recent years, the United States has claimed that Russia is developing a space nuclear weapon. In particular, Russia’s Cosmos 2553, launched in February 2022, would be a test of a potential future nuclear weapon in orbit. Russia has denied this. The satellite passes through a band of radiation called the inner band Van Allen callsthe lower of the two belts that surround the Earth.
“It’s a terrible place to put a satellite. You’re going to damage your satellite with all that radiation,” Danagoulian says. But it would be a good place to detonate a nuclear weapon. Radiation from the explosion would accumulate in the belt, attracted by Earth’s magnetic field, and wipe out thousands of satellites orbiting below.
But the Van Allen belt can also help reveal the presence of nuclear weapons. The high-energy protons in the belt would interact with the uranium in a bomb, producing a multitude of neutrons. A small satellite could be equipped with detectors that would detect neutrons coming from the direction of the target satellite, Danagoulian proposes. Additional detectors would eliminate signals from protons and electrons. The inspection satellite could identify a thermonuclear weapon 4 kilometers away after tracking its target for about a week, Danagoulian’s simulations suggest. With an even closer approach or with several inspector satellites, the measurement could be carried out in just a few hours, in a single pass.
“There are a lot of things about this work that are really interesting and exciting,” says astrodynamicist Thomas González Roberts of Georgia Tech in Atlanta. But, he notes, “the satellite with this detection device… would have to maneuver to be close, very, very close” to the target satellite. In the past, satellites approaching from dozens of kilometers away have frustrated operators, Roberts says.
Without coordination between the operators of the two satellites, such proximity could even increase the possibility of a collision, Roberts says. He thinks the idea would work better if it were part of a formal verification system incorporated into a treaty, rather than unannounced monitoring. Satellite operators could thus coordinate their maneuvers.
However, satellites capable of detecting the presence of nuclear weapons could change the situation. “It’s really important to have verification mechanisms,” says political scientist Victoria Samson of the Secure World Foundation in Washington, DC, who was not involved in the work. “It’s not just saying, ‘We’re asking you not to do this,’ but more like, ‘We can tell if you have something up there.'”
