
NASA counts down to first test of "planetary defense" against asteroids
CBSN
NASA is launching a small probe Wednesday that will crash head-on into a small asteroid next fall at some 15,000 mph to test the feasibility of one day nudging a threatening body off course just enough to prevent a catastrophic impact on Earth.
The $330 million Double Asteroid Redirection Test, or DART, "will be historic," said Tom Statler, mission program scientist at NASA Headquarters. "For the first time, humanity will change the motion of a natural celestial body in space."
The 525-foot-wide target asteroid, known as Dimorphos, is actually a small moon orbiting a half-mile-wide parent body named Didymos. Neither poses any threat to Earth, either before or after the DART encounter.

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, which they have dubbed "Planet Nine."