A meteorite hurtling toward Earth can be deflected without the use of a spacecraft.
According to a report published in the journal Nature Physics on September 23, the secret lies in using X-rays to change the trajectory of a meteorite. In laboratory experiments, scientists heated the surfaces of simulated meteorites in free fall using X-ray radiation, creating vapor columns that pushed the objects away. Subsequent computer simulations showed that X-rays emitted from a nuclear explosion at a distance could deflect several meteorites with widths comparable to the length of the National Mall in Washington, D.C.
A new study shows that X-rays emitted from a nuclear explosion can deflect asteroids as they approach Earth.
Physicist Nathan Moore from Sandia National Laboratories in Albuquerque stated: “Only one proposed method has enough energy to deflect the most dangerous meteorites, the largest ones, or in some cases even smaller meteorites when the warning time is short”, potentially just a year or less. “The planetary defense community agrees that X-rays from a nuclear device would be the only option in those situations.”
Theoretically, such explosions would occur at a safe distance from Earth.
Two years ago, NASA successfully guided a spacecraft to collide with the asteroid Dimorphos, altering the orbit of this cosmic rock around a larger asteroid. This was a significant moment for the Earth defense community. However, Mr. Moore noted that such collisions are only effective if the meteorite is small and there is enough time to change its trajectory. Thus, he and his colleagues began testing the deflection power of X-rays.
The experiments started in a vacuum chamber containing a simulated meteorite, the size of a blueberry and made of quartz—a common mineral found in meteorites. Using the world’s most powerful X-ray generator, the research team directed X-rays into the chamber for 6.6 nanoseconds. The X-rays vaporized the metal supports that held the quartz in suspension, causing the mineral to fall freely. It also heated and vaporized the surface of the falling mineral, creating a gas column.
Mr. Moore explained that the expanding gas column pushed the quartz away like rocket exhaust, propelling the mineral away from the X-ray source at a speed of about 250 km/h. Tests with molten silica yielded similar results.
To assess the feasibility of this method for planetary defense, the experimental results need to be incorporated into computer simulations. The research team discovered that X-rays from a nuclear explosion several kilometers away could deflect a meteorite with similar composition up to 4 km wide.
The researchers hope to conduct similar experiments with iron and other components of meteorites. Mr. Moore concluded: “Meteorites come in various types, composed of different minerals. This is just the beginning.”
