The asteroid NASA is about to strike poses no threat to Earth, but 60% of city-killer rocks fly under the radar

Illustration of DART approaching Dimorphos.

NASA is about to slam a spacecraft into an asteroid to nudge it into a new orbit.
The Double Asteroid Redirection Test (DART) is practice for deflecting an asteroid away from Earth.
But NASA can’t protect Earth if it doesn’t see asteroids coming, and its surveillance is weak.

NASA is about to slam a spacecraft into an asteroid, obliterating the probe and nudging the space rock.

The Double Asteroid Redirection Test (DART) is aiming for an asteroid called Dimorphos, which is orbiting a giant asteroid called Didymos. By crashing into it, NASA hopes to push the smaller space rock into a new orbit closer to its parent asteroid. The impact, scheduled for Monday, is practice for deflecting dangerous asteroids away from our planet.

When DART impacts Dimorphos, it should push the asteroid into a new orbit closer to Didymos.

Dimorphos is 163 meters (535 feet) wide — big enough to obliterate a city like New York. That’s no cause for concern, since it isn’t on an Earth-bound trajectory, and DART won’t change its path through the solar system. But that makes it perfect practice for one of the biggest threats in our cosmic neighborhood: city-killer asteroids, clocking in at 140 meters (460 feet) or larger.

Having a tried-and-true deflection method won’t help protect Earth from asteroids if nobody sees them coming, though. Experts previously told Insider that NASA would need five to 10 years to build and launch a customized mission to deflect an incoming asteroid. To date, scientists have only identified 40% of city-killer asteroids orbiting near Earth, NASA estimates. Nobody knows where the rest of them are, or where they’re going.

The 160-meter diameter Dimorphos asteroid compared to Rome’s Colosseum.

“Of course, you can’t use any mitigation techniques unless you know where the …read more

Source:: Businessinsider

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