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Can NASA hit an asteroid with DART?


The largest asteroid impact in recorded history occurred in Siberia in 1908. This asteroid never actually impacted the surface, but the force of its entry into the atmosphere was powerful enough to cause an air burst – a giant atmospheric explosion that flattened over 80 million trees and caused several deaths.

For years, we have assumed that we are at the mercy of such catastrophic impacts. An asteroid of great enough size, today, if on track to collide with Earth, could bring an abrupt end to the human species.

But what if it was possible to alter the course of this hypothetical asteroid, perhaps dodging our own mass extinction? Talk of such a feat sounds a bit like the stuff of science fiction movies. But this winter, NASA’s Planetary Defense Team has their sights set on testing our ability to do just that.

The Double Asteroid Redirection Test, better known as ‘DART’, will be the first attempt at actually altering the path of an asteroid. DART’s target is a binary asteroid system. The main asteroid, Didymos, is orbited by its smaller twin, the 500-foot wide Dimorphos, and it is Dimorphos that the DART spacecraft will impact.

The DART spacecraft is roughly a four foot cube furnished with a camera for navigating to the asteroid. 28 foot-long solar-powered panels extend like wings from either side of the box. It is also equipped with a sort of “side-car” attachment that will detach from the main spacecraft to photograph the collision from afar. DART will need to travel about seven million miles to reach Dimorphos. Upon arrival, DART will crash into Dimorphos at a speed of 4.1 miles/second. That’s about 20 times the speed of a bullet exiting a 9mm handgun. Scientists hope that DART’s impact will be enough to physically alter Dimorphos’s orbital path, in turn, speeding up its orbit around Didymos by several minutes.

To be clear, this asteroid system poses no actual threat to planet Earth; it is simply an accessible candidate for this unprecedented test. DART will launch sometime between late November 2021 and mid-February 2022, with the actual collision scheduled for late September or early October of 2022.

If DART is successful in its mission, it could mean that the power to deflect an Earth-bound asteroid would rest in our hands. Such an intervention, if pursued, could completely change the fate of our planet – the fate of our very selves.

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Western Slope Skies is produced by the Black Canyon Astronomical Society. This episode was written and recorded by Gina Loewen, park ranger at Black Canyon of the Gunnison National Park.