A vivid drama in outer space last week was provided by a NASA mission to prepare for the potential disaster of an asteroid traveling toward Earth. Though the chance of that emergency is remote, the risk exists. So America's space agency built and launched a one-way probe called the Double Asteroid Redirection Test (DART). After 10 months in space, the 1,260-pound craft hit its asteroid target and transmitted crisp video until the violent crash about 7 million miles from this planet. It was the first try by any country to knock an asteroid off course in case that's needed to save humanity -- which only sounds like a science-fiction movie. "This demonstrates we are no longer powerless to prevent this type of natural disaster," says NASA official Lindley Johnson.

Though billions of asteroids and comets orbit our sun, few are potentially hazardous to Earth. For at least the next century, no known asteroid threatens our planet. Still, long before any crisis may loom, NASA and international space agencies wanted to test a defensive protection technique known as kinetic impact. It was used against an asteroid measuring 530 feet in diameter, which orbited a much larger (2,560-foot) asteroid. Neither threatened Earth. Ground telescopes will track the bumped asteroid to confirm that DART's impact altered its orbit.

The relatively small DART craft, about the size of a golf cart or vending machine, was no match for the heavier asteroid – as big as an Egyptian pyramid. But the high-speed impact is believed to have been enough to slightly alter the space rock's movement and velocity. That would be a planet-saver if one were on a collision path, especially, if done early enough — such as five to 10 years before a projected encounter with our globe. The Atlantic magazine put it this way in a headline last week: "Maybe We Won't End Up Like the Dinosaurs."

NASA chief says: "DART represents an unprecedented success for planetary defense, but it is also a mission of unity with a real benefit for all humanity. This international collaboration turned science fiction into science fact, demonstrating one way to protect Earth." – Bill Nelson, space agency administrator

Space buff says: "We can identify and track asteroids' orbits in greater detail than ever before. Investing in planetary defense missions such as DART brings us closer to preventing what has always seemed unpreventable." – Rae Paoletta, editorial director for the Planetary Society, a nonprofit group in Pasadena, Calif.

Historic asteroid impact: About 66 million years ago, a six-mile-wide asteroid slammed off the coast of what is now Mexico's Yucatán Peninsula. It changed Earth's orbit and brought an Ice Age that made dinosaurs extinct.