Astronomers have identified a possible threat from asteroid 2024 YR4, which has a slim but concerning 4% chance of colliding with the Moon in 2032. While earlier assessments suggested a potential impact with Earth, scientists have since ruled that out. Nevertheless, the implications of a lunar impact could be significant, as it may release a large volume of micrometeoroid debris into low-Earth orbit, putting both spacecraft and astronauts aboard the International Space Station at risk.
A recent study by researchers from NASA and various U.S. institutions has explored potential strategies for preventing this scenario. Their findings were submitted to the Journal of the Astronautical Sciences for peer review and have been made available on the preprint server arXiv. The authors analyze multiple options for deflecting or destroying the asteroid, ultimately concluding that destruction may be the most feasible approach.
Challenges of Deflection
The preferred method for dealing with asteroids typically involves deflection. However, this strategy carries risks. If executed incorrectly, deflection could turn one large threat into several smaller, unpredictable fragments. This uncertainty stems from the difficulties in accurately assessing the asteroid’s mass and density, both critical for calculating the required energy to alter its trajectory.
The James Webb Space Telescope recently measured the diameter of 2024 YR4 at approximately 197 feet (60 meters). Yet, without a clear understanding of its composition, estimating its mass remains challenging. According to the researchers, the asteroid’s mass could range from 74 million pounds (33 million kilograms) to over 2 billion pounds (930 million kilograms). This wide range complicates any calculations and raises the risk of miscalculating the energy needed to nudge 2024 YR4 off course, potentially redirecting it toward Earth instead.
To refine estimations of 2024 YR4’s mass, NASA could consider a reconnaissance mission. However, the optimal window for such a mission would be 2028, leaving only three years for development—a notably tight timeline. Given these constraints, the researchers conclude that deflection missions may not be practical for preventing a lunar impact.
Exploring Destruction Options
Faced with these challenges, the study advocates for destruction as a more viable alternative. The researchers propose two primary methods for accomplishing this. The first is a robust kinetic disruption mission, akin to NASA’s successful Double Asteroid Redirection Test (DART) mission. Rather than merely nudging the asteroid off course, this approach would aim to break 2024 YR4 apart. Although this concept has not been previously tested, the researchers note that NASA would have sufficient time to develop this mission, with the next available launch window between April 2030 and April 2032.
The second method involves detonating a nuclear device on, near, or beneath the surface of 2024 YR4 to fragment it into smaller pieces. While this approach also lacks prior testing, it remains theoretically possible. According to the researchers, the next available launch window for such a nuclear mission would be between late 2029 and late 2031.
Despite the uncertainty surrounding asteroid 2024 YR4’s close approach, scientists view this situation as a unique opportunity. With several years before the potential impact, researchers can refine techniques for preventing not only lunar impacts but also those that could threaten Earth. As the study highlights, proactive measures now could ensure preparedness for any future threats to our planet and its natural satellite.