A new study proposes using shoebox-sized detector satellites to sniff out nuclear weapons launched by adversary nations. The idea is aimed at addressing fears that a space-based nuclear detonation could destroy satellites across low Earth orbit and make some orbits unusable for years. Space.com shares the findings from a new paper authored by Areg Danagoulian, an associate professor of nuclear science and engineering at the Massachusetts Institute of Technology: No reliable way currently exists to detect and defuse a nuclear bomb in space. Danagoulian proposes a constellation of small "9U" cubesats, each one about the size of a large shoebox and each carrying a special detector capable of sensing radiation emitted by unexploded nuclear bombs. He explores a scenario in which Russia launches a suspected space nuke into an orbit with an altitude of 1,200 miles (2,000 km). That number is not random. In 2022, Russia's Kosmos 2553 satellite, orbiting at that exact altitude, triggered suspicions it might be testing components for a future orbital nuclear weapon. Russia claims the satellite just observes Earth. At that altitude, the satellite passes through the Van Allen belt, a region of intense cosmic radiation trapped by Earth's magnetic field. Most of the belt stretches between altitudes of around 600 miles (1,000 km) to tens of thousands of miles, but in some areas the radiation can reach much closer to Earth's surface. The interaction between the fissile material inside the nuke and the energetic particles from the radiation belt would create distinct signatures, Danagoulian said, which could help confirm whether a suspicious satellite carries a nuke or not. "The thermonuclear weapon would contain a significant amount of uranium," Danagoulian said. "The high-energy protons [in the uranium] would break up when another proton is coming in and shred the nuclei. That would knock out a large number of neutrons. This interaction turns that device into a very intense neutron source that otherwise would not be there." he process is known as proton-induced neutron spallation, which essentially means the ejection of fragments from material triggered by impacts of protons. The detector satellite Danagoulian proposes would have to be able to get quite close to the suspect spacecraft -- a few kilometers. The inspector spacecraft would carry a sensor combining two types of detectors. At the heart of the device is a neutron scintillator, which detects all incoming neutrons and protons. Around it is a "cage of diamond" detector that detects only neutrons -- not protons. Such a set-up helps filter out the particles present in the environment naturally, said Danagoulian. In addition, by using two "planes of neutron detectors," the sensor can determine the direction from which the neutrons arrived. "If the external diamond detector triggers and gives a signal, you can ignore the particle, because it's most likely a proton and not a neutron," said Danagoulian. "Once you identify those neutrons, by having those two detections, you can back project and find out where the neutron came from." Danagoulian says such a nuke sniffer would have to be launched into an orbit aligned with that of the suspicious satellite and creep up as close as 2.5 miles (4 km) from it. It would then take about a week to gather enough measurements to confirm whether the object is hiding a nuke or not. A constellation of 10 such satellites could reduce the process to mere hours, Danagoulian said. If a nuke were detected, the military could then try to jam the satellite's communications link from the ground, making it impossible for the adversary to remotely detonate the bomb. There is currently no technology available to safely defuse a nuclear weapon in space. [...] Danagoulian also suggests that high-grade radiation hardening could improve satellites' chances of surviving a nuclear winter in space. The paper has been published in the journal Nature.Read more of this story at Slashdot.