Hecla and Kemp constrained the Burevestnik's design to a subsonic direct-cycle nuclear turbojet using only open-source data

Using only openly available data — Russian Ministry of Defence videos and photographs, satellite imagery, and prior reporting — MIT researchers Jake J. Hecla and R. Scott Kemp built a "nuclear-aircraft modeling toolkit" to physically constrain the design of Russia's Burevestnik (NATO: 9M730 "Skyfall"), a system claimed to be a nuclear-powered, nuclear-armed cruise missile capable of nearly indefinite flight. Treating a state secret's public imagery as a physics dataset, they conclude the missile is a subsonic cruise missile measuring 9.5 ± 0.32 m in length with a 5.6 ± 0.18 m wingspan, and that it is "likely powered by a direct-cycle nuclear turbojet," with their calculations "almost entirely" excluding a nuclear ramjet.

The result is an instance of open-source intelligence (OSINT) done as forensic first-principles engineering rather than as image-tagging or geolocation: the design space of a classified weapon is narrowed by what the physics of air-breathing nuclear propulsion will and will not permit. The paper's authors describe their toolkit as general-purpose for "air-breathing nuclear propulsion systems," suggesting the method — not only this result — is the reusable contribution.

The propulsion-type finding is load-bearing for the paper's downstream estimates: the direct-cycle architecture (reactor air passed directly through the core) is what drives the modeled reactor thermal power and, crucially, the prediction of a radioactive exhaust plume.