The space mission launched to protect Earth

A first-ever space mission to avert the potential threat of an asteroid collision wiping out life on our planet has launched successfully, Nasa has announced.

Carried aboard a SpaceX-owned Falcon 9 rocket, the Dart (Double Asteroid Redirection Test) spacecraft lifted off from Vandenberg Space Force Base in California on Wednesday morning. Never before “in human history has our species tried to knock an asteroid away from our world”, said The New York Times (NYT).

The “refrigerator-size” probe, which weighs less than 550kg, “will trek around the Sun to slam into a small asteroid named Dimorphos at 15,000 miles per hour next year”, the paper reported.

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The spacecraft is expected to collide with Dimorphos, which orbits a bigger astroid called Didymos, between 26 September and 1 October 2022.

According to The Guardian, “cameras mounted on the impactor and on a briefcase-sized mini-spacecraft to be released from Dart about ten days beforehand will record the collision and beam images of it back to Earth”.

Dart project manager Ed Reynolds told a news conference on Monday that the pair of asteroids, which are about 6.8m miles from Earth, provide the “perfect environment to test this methodology”.

This week's lift-off was shown live on Nasa TV and on the SpaceX Twitter account, and has been celebrated worldwide. The mission is “packed with milestones”, said space.com, “especially in the first few weeks after launch”.

“The Dart team won't be twiddling its thumbs until the big collision,” the site continued. Another in a series of planned big moments “will come about 20 days into flight”, when they fire up Nasa's Evolutionary Xenon Thruster-Commercial (NEXT-C) engine, “a solar-powered ion propulsion system that could find its way onto future spacecraft”, for its first in-space test.

The main mission, to deflect an asteroid, is “a dry run for the real deal”, said Scientific American. “One day, a technological descendant of Dart could be used to deflect a planet-threatening space rock, saving millions – perhaps billions – of lives in the process.”

The odds of such a collision impacting an asteroid’s orbit are “100%”, said Dart’s Reynolds. But much still depends on whether the spacecraft can hit its target. “We keep working harder and harder not to miss,” he added.

If the intended Dart collision were to fail, the spacecraft should have enough fuel to make a new attempt on a different space rock.

If successful, Nasa will have “a confirmed weapon in its planetary-defence arsenal”, said the NYT.

But “there are no silver bullets in planetary defence”, Scientific American cautioned. “The bizarre and variable geology of asteroids may serve to rebuff our deflection attempts, our network of early-warning telescopes is rife with gaping observational holes, and the politics of deciding who can try to deflect an inbound impactor are fraught with uncertainty”.

Yet there is no doubt that Dart “represents a major step forward”, the magazine added.

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