NASA scientists propose nuclear disruption to halt 'city-killer' asteroid 2024 YR4 from hitting the Moon

An international team of researchers, including experts from NASA, has outlined a nuclear disruption strategy to prevent asteroid 2024 YR4 from colliding with the Moon. The plan, described in a recently posted arXiv preprint, envisions using nuclear devices to break the space rock apart rather than simply nudging it off course. The study argues that a nuclear approach could be launched within a timeframe of several years, depending on safety reviews and funding, and that it may offer a viable path given tight reconnaissance windows.

Under the proposal, two 100-kiloton nuclear devices would be dispatched to YR4 and would autonomously steer themselves to the target. The detonations would create a fragmentation event with a total energy roughly five to eight times the atomic bombs dropped on Nagasaki and Hiroshima in 1945. One device would detonate first; a second would be kept on board as a backup and could be deployed if needed, with the option to detonate in deep space after the asteroid is successfully deflected by the first one. The team also suggested that a non-nuclear option could be pursued as a contingency, but emphasized that the nuclear approach might be needed if time runs short for other methods.

The authors described a capability to launch these nuclear devices in as little as four years from now, contingent on regulatory approvals and mission safety clearances. They also noted that for planning purposes, a broader assessment indicated a five- to seven-year horizon to develop the concept, with potential launch windows spanning 2029 to late 2031. The study’s framing reflects the high-stakes nature of defending a distant, but potentially dangerous, object that could alter lunar operations or generate debris that affects space assets.

Deflection-type missions, such as NASA’s 2022 Double Asteroid Redirection Test (DART), were evaluated as an alternative to nuclear disruption. DART-like tactics aim to alter an asteroid’s trajectory by imparting momentum through a kinetic impact. However, the authors concluded that such missions were impractical for YR4 given the short timeline and uncertainty about the asteroid’s size and mass, which would require reconnaissance that could not occur quickly enough. At roughly 379 million miles away, YR4’s precise characteristics would need detailed study before any interception op could be confidently executed; the paper argued that recon would not be feasible until 2028, leaving only about three years to respond after a decision to act.

NASA’s Center for Near-Earth Objects (CNEOS) has continued monitoring of YR4. In latest risk assessments, the agency downgraded the probability of Earth impact to a negligible 0.00081 percent. By contrast, the report notes a lunar-impact probability exceeding 4 percent for the December 23, 2032 date. If YR4 were to strike the Moon, the resulting debris could pose risks to Earth-orbiting satellites, potentially disrupt lunar landers, and threaten Artemis-era missions and astronauts. The analysis emphasizes that even a low likelihood of lunar impact would carry outsized consequences for space operations and would compel consideration of mitigation options.

The study points to ongoing observational inputs from space- and ground-based facilities, including imagery from NASA’s James Webb Space Telescope. Webb’s observations contribute to estimates of YR4’s size, shape, and rotation state, all critical inputs for any deflection or disruption plan. The authors caution that their proposal is theoretical and not an official NASA directive, and they acknowledge that the arXiv posting is not yet peer-reviewed. They describe the work as one possible response within a broader set of risk-management considerations for near-Earth objects.

If pursued, the nuclear disruption option would require global governance, rigorous safety protocols, and robust international oversight given the dual-use nature of space nuclear technology and the potential for fallout to other spacecraft or planets. The authors stress that any decision to employ such a method would involve extensive verification, orbit prediction updates, and cross-agency coordination before launch. They also note that this approach concentrates on a worst-case, lunar-impact scenario; in reality, decision-making would weigh multiple threat assessments and mission constraints as they evolve.

The concept remains speculative and is part of a broader scientific discourse about how humanity might counter significant asteroid threats in the future. While the Earth-facing risk from YR4 is described as small, the lunar risk is nonzero, and the paper underscores the importance of readying a diverse set of viable options for planetary defense. The authors reinforce that additional peer review, simulations, and safety reviews would be necessary before any real-world deployment could be contemplated.

As space agencies and researchers continue to monitor YR4, these discussions illustrate the range of theoretical strategies scientists consider to mitigate near-Earth threats. They also highlight the complexities of planetary defense planning, where the difference between Earth protection and lunar risk can hinge on small changes in timing, scale, and mission architecture. For now, the public-facing takeaway is that, yes, a nuclear disruption option exists as a theoretical possibility for a distant and uncertain threat, but any move toward actual implementation would require careful international deliberation and a rigorous validation process.