THE WOODLANDS, Texas – If You Want to Use a Nuclear Weapon to Save the World from asteroid, do not try to do it Bruce Willis did in "Armageddon," NASA's planetary defense
"When you've seen those movies, they're completely bogus," Lindley Johnson, the planetary defense officer at NASA headquarters, said during a media session on asteroids and the art of Protecting Earth from them Held at the Lunar and Planetary Science Conference.
But nuclear weapons are one of three techniques planetary defense experts have their eyes on for asteroid off course too close to Earth for comfort. Another method, impacting an asteroid, is being tested for the first time during the Double Asteroid Redirection Test a NASA mission scheduled to launch in June 2021
Related: 7 Great Movies with Earth-Threatening Asteroids
Another tactic would use gravity to slowly tug at asteroid far enough off course to miss Earth. [More]
All three of these techniques take the same basic approach: adjust the asteroid's orbital speed so its no longer intersects with our own. "We just need to change that speed by maybe a couple of centimeters per second," Johnson said. That's all we need. "That's all we need . "
To get that change in velocity from a nuclear explosion, however, there's no need to actually touch the asteroid directly, Johnson said. Instead of doing so, the effects on the surface of the asteroid on that side, heats it up, superheats the surface, "he said. "That surface wants to blow off the asteroid."
And because the laws of physics apply quietly, the dramatic action triggers on equal and opposite reaction, with the asteroid rebounding away – exactly what's needed to avert a catastrophe here on earth , Johnson, a flyby would do.
It was a nice thought, Bruce.