San Diego Union-Tribune

NASA SET TO SHOOT ROCKET AT ASTEROID

Scientists want to test ‘planetary defense’ strategy

- BY BRYAN PIETSCH Pietsch writes for The Washington Post.

NASA will launch a spacecraft next month to hit an asteroid — on purpose — to change its path, testing for the first time a method of “planetary defense,” the agency announced Tuesday.

The launch of the Double Asteroid Redirectio­n Test (DART) mission will occur at 1:20 a.m. Eastern time on Nov. 24, NASA said. A SpaceX Falcon 9 rocket will be launched from the Vandenberg Space Force Base, about 50 miles northwest of Santa Barbara.

NASA is targeting a pair of asteroids that orbit the sun and occasional­ly come close to Earth. The asteroids don’t come close enough to pose a threat, NASA says, but their proximity makes them a prime candidate for the test of a technique that could someday prevent a “hazardous asteroid from striking Earth.”

“We’re going to make sure that a rock from space doesn’t send us back to the Stone Age,” Thomas Statler, a NASA scientist, said on the agency’s podcast.

The larger of the two asteroids, Didymos, is about a halfmile across in size, with a smaller “moonlet,” called Dimorphos, orbiting it. Dimorphos, about 500 feet in size, is “more typical of the size of asteroids that could pose the most likely significan­t threat to Earth,” according to NASA.

Dimorphos is “not necessaril­y the asteroid that’s going to cause [a] devastatin­g effect on Earth,” Statler said. Rather, the launch is a “test to make sure that we have the capabiliti­es for that asteroid in the future, if there is one.”

The DART mission is aiming to hit Dimorphos at a speed of nearly 15,000 miles per hour with the goal of changing its orbit “by a fraction of 1 percent” — a small but significan­t enough change that scientists will be able to observe it from telescopes on Earth.

If NASA were to detect an asteroid that poses a risk to Earth — Statler said the agency is not aware of such a risk over the next hundred years — it would attempt to hit it and change its course, rather than destroy it altogether.

The DART spacecraft will detach from the SpaceX rocket and cruise in space for more than a year before it hits Dimorphos sometime late September next year.

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