A probe as a cosmic cue to tap an asteroid away

Pandemics, earthquakes, volcanic eruptions, wars, climate change. There are a lot of disasters that can hit us as humanity. But none are potentially as devastating as a giant asteroid colliding with Earth.

65 million years ago, the dinosaurs went extinct when that happened. The chance is nil in the short term, but such a collision will happen again. So we better prepare for it and try to prevent it, according to space organizations.

NASA will launch a vehicle into a twin asteroid tomorrow morning for a unique test. Can we change the orbit of a celestial body by aiming a probe at it at high speed, as a cosmic cue? The DART mission must answer the question of whether that’s a realistic way to save us from an asteroid on a collision course with Earth.

Collision at 22,000 kilometers per hour

DART stands for Double Asteroid Redirection Test. The mission goes to a double asteroid. Around Didymos – diameter 780 meters – orbits the moon Dimorphos – diameter 160 meters. NASA’s probe will arrive there at the end of September next year, when the asteroids are 11 million kilometers from Earth. Then the vehicle is supposed to hit Dimorphos at 22,000 kilometers per hour.

A double asteroid was deliberately chosen, says astronomer Lucas Ellerbroek: “It is easier to effect a change in the orbit of the small asteroid around the large asteroid than the orbit of an asteroid around the sun.” A satellite of the Italian space agency ASI and a probe of the European space agency ESA take images and measure the impact.

When changing the job, we should not imagine too much. “It’s like shooting a pea at a basketball,” Ellerbroek said. If the mission succeeds, the orbit will shift a fraction of a percent, NASA says. “But a small change in orbit can make a big difference, if you do it early enough. The sooner you hit an asteroid, the smaller the push needs to be.”

A little push can make a big difference:

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