Our probe looks a little like a giant bat.

Star Bound №16: NASA Throws a Dart

Bruce McCandless III
3 min readSep 20, 2022

Practicing for the Ultimate Environmental Defense Mission

Let’s face it. You may not care about the composition of Jupiter’s Trojan asteroids. Your concern about whether Pluto has ice volcanoes is probably minimal. But trust me, you should care about NASA’s DART (Double Asteroid Redirection Test) mission.

It’s a kamikaze flight, in a sense — a probe launched from Earth several million miles into space with the aim of smacking an asteroid called 65803 Didymos. It should be noted that Didymos is not itself a threat to Earth. Also of interest is the fact that Didymos is actually two little asteroids, with the smaller called Dimorphos and classified as an “asteroid moonlet” of the larger. The impact will occur on Dimorphos. If all goes well, our probe will cause a slight shift in the trajectory of this binary asteroid system. And if Didymos can be nudged into a slightly different course, it stands to reason that we could do something similar to a larger asteroid making a beeline for Kansas, Kenya, or Kamchatka.

And that could be a very big deal.

There are millions of asteroids in our solar system. They soar past Earth more or less constantly, with a few— 17 a day, in fact — perforating our atmosphere as meteors and smashing into Earth’s surface. Generally speaking, they’re harmless. Some are even inspirational. Take, for example, the Ensisheim Meteorite, which landed in an Alsatian field in 1492. Its arrival was heralded as a positive omen by Maximilian, son of the Holy Roman Emperor, as he prepared to wage war against the French. He may have been right. At any rate, he won.

But a large asteroid impact is not healthy, as the saying goes, for children and other living things. The so-called Tunguska Incident in 1908 resulted in the destruction of millions of Siberian trees and an untold number of native animals. The granddaddy of them all, a city-sized asteroid that struck the planet near Mexico’s Yucatan Peninsula some 66 million years ago, wiped out numerous species of flora and fauna and reshaped life on Earth. In the 1998 blockbuster “Armageddon,” we hear that this cosmic buzzkill smashed into what is now the Gulf of Mexico with the force of “10,000 nuclear weapons,” instantly vaporizing millions of gallons of ocean and creating a global dust cloud that blocked out the sun, killing plants and animals alike. As bad as that undoubtedly was, the next big asteroid to hit us could be worse. People would die. Cities would perish. Whole nations would vanish from the earth. Basically, observes noted asteroid scientist Billy Bob Thornton in the film, it would be “all the worst parts of the Bible.”

But NASA has a plan. Under the direction of the agency’s Planetary Defense Coordination Office — undoubtedly the coolest government name ever — and in collaboration with the Italian Space Agency, NASA’s DART mission is carrying out what may one day prove to be a dress rehearsal for an actual asteroid deflection. The first step, of course, is identifying an incoming asteroid. The next is getting to it in time to deflect it. The DART probe left Earth atop a SpaceX Falcon 9 rocket in late November of 2021. It is currently just a few days from impact, which is scheduled for September 26. It is flying itself, executing a series of automated course corrections as it approaches Didymos, and it recently deployed its ISA-manufactured paparazzo, a little mechanized spy called LICIACube (Light Italian Cubesat for Imaging Asteroids). LICIA’s job will be to record the impact for study, as DART is not expected to survive the collision. This should come as no surprise, given that our probe will strike the moonlet at a speed of around four miles per second.

If all goes well, Didymos will be nudged off its current course and a whole bunch of scientists will breathe a sigh of relief. So should the rest of us. Hollywood movies notwithstanding, launching a crewed mission of grizzled deep-core drillers to an asteroid in hopes of planting a nuclear device inside it is probably not a viable tactic, especially now that Bruce Willis is getting on in years. But asteroid redirection is, or may be, a workable solution.

We’re about to find out — and future generations will thank us for it.



Bruce McCandless III

I'm an Austin-based writer trying to figure out space, science, and Texas politics. For more, see: www.brucemccandless.com