the The largest-scale planetary defense test took place in 2022, when NASA's DART probe collided with a 160-meter-wide asteroid and changed its course.
But the shockwave caused by Dart, which was the size of a large refrigerator, may not be enough for a larger object.
Chicxulub, an asteroid about 10 kilometers across, is one such asteroid, and scientists say its impact on Earth, 66 million years ago, plunged it into a winter that wiped out three-quarters of Earth's species.
The 1998 action movie “Armageddon” depicted a scenario in which a team as reckless as it was heroic prepared to approach a 1,000-kilometer-wide asteroid before destroying it with a nuclear bomb.
This week, North American researchers published in the journal Nature Physics an experiment on a more modest asteroid, 12 millimeters wide, which was exposed to a blast of X-rays at Sandia National Laboratories in Albuquerque, New Mexico.
The machine is capable of producing “the brightest beam in the world,” the study's first author, Nathan Moore, who works at Sandia, told AFP.
Most of the energy released in a nuclear explosion is in the form of X-rays. In space, because there is no atmosphere, there would be no shock waves or fireballs.
At Sandia, X-rays easily vaporized the surface of the small asteroid and the vaporized material pushed the target in the opposite direction.
Acting as a “rocket engine,” according to Moore, the test sent the target flying at 250 km/h, confirming “for the first time” theories that predicted such an effect.
The researchers used two types of small asteroids, one made of quartz and the other of silica, and built a model that concluded that a nuclear explosion would be enough to change the course of an asteroid four kilometers in diameter, provided there was sufficient advance warning.
The model used assumes a 1-megaton bomb, more than 60 times more powerful than the one used in Hiroshima, which should explode a few kilometres from its target, but millions of kilometres from Earth.
Conducting an experiment of this kind under real conditions would be dangerous, expensive and contrary to all international treaties.
But nothing is stopping us from studying the subject and “preparing for all scenarios,” because, as Moore explains, “the biggest uncertainty right now” is that asteroids “come in all kinds.”
DART’s target, Dimorphos, turned out to be a fragile pile of cosmic rubble, and the European Space Agency’s Hera mission, which launches next month, is expected to examine it in more detail.
Mary Bourke, a researcher at Lawrence Livermore National Laboratory in California, ran computer simulations of using a nuclear weapon to deflect an asteroid.
She told AFP she was pleased that her calculations agreed with the Sandia team's observations.
Their simulations show that this type of mission “would be a very effective way to defend the planet against any impact.”
Read also: Earth will have a “mini-moon” in the near future
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