If an asteroid were directed toward a collision with the moon, what actions should humanity consider? Perhaps we could attempt to divert the asteroid from its path before impact or eliminate it entirely with a nuclear blast?
These are the dilemmas addressed in a new paper by over a dozen researchers, including several from NASA. While it may sound like science fiction, it’s a real concern: An asteroid called 2024 YR4 has an estimated 4% chance of impacting the moon in 2032.
Such an impact could generate debris reaching “up to 1,000 times the normal levels within just a few days, potentially endangering astronauts and spacecraft” in low-Earth orbit, according to the researchers who wrote the paper, made available on the preprint website arXiv on September 15, although it hasn’t been peer-reviewed yet.
To prevent the formation of this hazardous debris cloud, one suggested approach involves nuking the asteroid, or initiating what the researchers refer to as a “robust disruption,” before it collides with the moon.
Cue the “Armageddon” movie references.
But using a nuclear explosion to destroy an asteroid has never been tested, so the plan would come with a slew of major risks.
Important details about asteroid 2024 YR4, such as its mass, remain unknown, which are crucial for determining how to effectively “disrupt” it without causing further complications.
“If the explosion isn’t sufficient, you’re simply creating a debris field regardless,” said Julie Brisset, interim director of the Florida Space Institute, who did not partake in the study.
Asteroid 2024 YR4 was first detected by the Asteroid Terrestrial-impact Last Alert System station in Chile in December. NASA estimates that it measures up to 220 feet across, large enough to be considered a “city killer” because it could be capable of causing severe damage to a city or region on Earth.
Experts initially thought there was a small chance the asteroid could hit our planet, and the probability of such an impact was estimated to be as high as 3% earlier this year. But a collision with Earth was later ruled out.
With Earth now thought to be in the clear, asteroid 2024 YR4 has an estimated 4.3% chance of smacking into the moon.
The authors of the recent paper suggested launching a mission to conduct reconnaissance of the asteroid, including estimating its mass from up close. After that, they proposed, an explosive device could be built, then deployed to the space rock.
Alternatively, if destroying the asteroid with a nuclear explosion is too extreme, the researchers detailed how it could be nudged out of the way.
NASA has some experience with that: In a first-of-its-kind test in 2022, its DART probe intentionally crashed into a small space rock known as Dimorphos to alter its trajectory. The maneuver was carried out 6.8 million miles from Earth and changed Dimorphos’ path in space, shortening its orbit by 33 minutes, according to NASA.
But a successful deflection would also require knowing the mass of asteroid 2024 YR4, Brisset said.
In response to an NBC News inquiry to NASA about the recent paper, Kelly Fast, the agency’s acting planetary defense officer, said in a statement that there are no plans to deflect or otherwise interfere with the asteroid.
However, she said there are plans to study it early next year using the James Webb Space Telescope. Any findings could provide better insight into its orbital path.
“If observed, the additional data could improve our knowledge of where the asteroid will be in December 2032,” Fast said, “and could drop the impact probability to 0%.”
Even if space missions like those described in the paper could be carried out, there would be political considerations to navigate.
Although no astronauts or long-term habitats are on the moon, that might not always be the case. China, for instance, has said it aims to land its astronauts on the moon by 2030. Chinese officials have also said the country may build a nuclear plant on the lunar surface to power a moon base that it plans to jointly operate with Russia.
The United States plans to launch regular missions to the lunar surface before NASA eventually ventures to Mars. But NASA’s future missions and priorities remain in flux amid significant personnel cuts and President Donald Trump’s budget blueprint for NASA, which proposes slashing more than $6 billion from its budget.
Detonating a nuclear device in space could also add tension to the burgeoning space race among the United States, China and other spacefaring countries, with potential conflicts over which countries and space agencies would lead or participate in the project, Brisset said.
“It would probably be countries that have the technical capability to do it,” she said, “which maybe narrows it down to three or four, but would they want to work together?”
