A world-ending asteroid, a nuclear bomb and one risky mission: Scientists explain their emergency plan to save Earth but there is a catch

A giant asteroid crashing into Earth may sound like the plot of a Hollywood disaster movie, but scientists say it is a real risk that space agencies cannot ignore. While there is currently no known asteroid on a collision course with Earth, researchers continue to study ways to deal with such a threat if one is discovered with very little warning.

A new study by researchers from the China Academy of Launch Vehicle Technology has proposed an extreme solution. Instead of simply trying to push an asteroid off course, the team suggests drilling deep into the space rock, placing a nuclear device inside it and detonating it from within. The findings were published in the journal Space: Science & Technology.

Why scientists think a nuclear option may be needed


The researchers say the biggest concern is a large near-Earth asteroid that is detected only days or weeks before a possible impact. In such a situation, existing planetary defence methods may not provide enough time to prevent a disaster.

The study states, "Mitigating the risk of near-Earth asteroid (NEA) impacts is critical to global security and the survival of human civilization."

It further says, "In particular, large NEAs with short warning times pose a devastating threat to humanity."

According to the researchers, "directly destroying or rapidly deflecting" such an object may be "the only feasible method" in some extreme cases.

The authors also wrote, "Asteroid impacts on Earth have occurred several times in human history, causing catastrophic environmental changes and mass extinctions."

"It is one of the major potential threats that could lead to human destruction and has therefore become a hot topic of concern in the international community," they added.

How the proposed mission would work

Unlike the approach shown in NASA's DART mission, which deliberately crashed a spacecraft into an asteroid to change its orbit, this proposal focuses on destroying the object from the inside.

The idea is to send a spacecraft carrying both a drilling system and a nuclear device. A conventional explosive would first create a deep crater inside the asteroid. The nuclear device would then be lowered into that crater before being detonated. Scientists believe an underground explosion would transfer far more energy into the asteroid than a blast on its surface, making it much more effective at breaking it apart or changing its path.

To test the concept, the team ran computer simulations using virtual asteroids travelling towards Earth at about six miles per second.

The simulations showed that a 300-kiloton nuclear explosion could completely destroy an asteroid about 50 metres (164 feet) wide. A much larger 3-megaton blast could break apart an asteroid around 100 metres (328 feet) across. The researchers also found that placing the nuclear payload roughly 100 metres below the surface could produce around three times the change in the asteroid's velocity compared with a much shallower explosion.

The biggest challenge is time

Despite the promising simulation results, the researchers admit that carrying out such a mission would be extremely difficult.

The asteroid would first need to be detected early enough for engineers to build, launch and guide a spacecraft across deep space before impact. The spacecraft would also have to carry heavy drilling equipment along with the nuclear device, making the mission far more complicated than simply crashing into an asteroid.

Scientists say this approach is meant only for the most dangerous situations where other options may no longer work.

"The defense against asteroid impacts on Earth has always been one of the major challenges in international astronautics," the researchers wrote.

They added, "Carrying out research on NEA defense is an inevitable choice for humanity to protect its survival and development."

The team concluded that the study "holds profound strategic significance for enhancing humanity's capability to respond to asteroid impact threats."

The research also comes as NASA has warned that as many as 15,000 several-hundred-foot-wide asteroids could still remain undiscovered. While none are currently known to threaten Earth, scientists say preparing for even unlikely scenarios is an important part of protecting the planet in the future.