NASA Launches 1St Mission To Defend Earth From Asteroids

US space agency Wednesday began its first test mission of a planetary defense system by launching a spacecraft that is intended to strike an asteroid with the hopes of causing a measurable change.

The DART, or Double Asteroid Redirection Test, was launched aboard a SpaceX rocket at 1.21 a.m. EST (0621GMT) from Vandenberg Space Force Base in central California.

The spacecraft is intended to intentionally collide with an asteroid at such speeds that it will change the asteroid's motion by a level that is measurable by land-based telescopes.

"DART is turning science fiction into science fact and is a testament to NASA's proactivity and innovation for the benefit of all," NASA Administrator Bill Nelson said in a statement.

"In addition to all the ways NASA studies our universe and our home planet, we're also working to protect that home, and this test will help prove out one viable way to protect our planet from a hazardous asteroid should one ever be discovered that is headed toward Earth," he added.

DART detached from the rocket at 2.17 a.m. (0717GMT) and began a two-hour process to unfurl its 28-foot (8.5 meters) long solar arrays, which will be used to power the spacecraft and its ion engine.

The spacecraft will cruise for about one year until it reaches its target: a pair of asteroids known as the Didymos system, and will crash into the smaller one, Dimorphos, at nearly 15,000 miles per hour (241,402 kilometers per hour), or 4 miles per second (6 kilometers per second). NASA stresses that the mission is just a test and the asteroids are not a threat to Earth.

It is expected to reach the Didymos system between Sept. 26 and Oct. 1, 2022.

The resulting collision is expected to only alter the speed of the moonlet by less than 1%, but NASA said in September that the crash "will change the orbital period of the moonlet by several minutes – enough to be observed and measured using telescopes on Earth."

DART's flight is intended to demonstrate the feasibility of next-generation ion engine technology, which NASA hopes to use in future space missions. -