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Asteroids impacting Earth can be devastating—killing all the dinosaurs in existence level devastating. But even the asteroids that aren’t mass-extinction huge can be a serious threat. Every few thousand years Earth (a.k.a. you and I) get hit with a massive asteroid the size of the Great Pyramid of Giza, so what is the plan when we get hit with the next asteroid?
We get hit with an asteroid about the size of the Great Pyramid of Giza every few thousand years, and when the next one hits it could cause massive damage to an entire region. So when we spot the next one coming, what’s the plan? Enter: NASA’s Planetary Defense Coordination office. The Planetary Defense Coordination office is tasked with coming up with ways to protect the planet from threats from outer space. And one of their great ideas is to smack a spacecraft head on with an oncoming asteroid to see if it can be slowed down and deflected.
Members of NASA, the European Space Agency, and others are informally collaborating with a pair of missions that together are known as the Asteroid Impact and Deflection Assessment, or AIDA. NASA is up first with a mission called the Double Asteroid Redirection Test, or DART.
The launch window opens on July 22, 2021, and the goal is to nail an asteroid by late September or early October the following year. Pretty cool, huh? The target DART is aiming at is one of a pair of binary asteroids called Didymos B. Didymos is Greek for twin, hence the Double part of DART. While the asteroid is not on a trajectory to hit Earth, it is an ideal candidate to see just how much of an impact will affect it because Didymos B is a moonlet 160 meters across that’s orbiting the much larger asteroid Didymos A, and as luck would have it, from our perspective it passes in front and behind the larger body, causing changes in the system’s brightness that we can measure. When DART hits Didymos B at 6.6 kilometers per second, the asteroid’s speed will change by a fraction of a percent, but that’s enough to change the time it takes to orbit Didymos A by several minutes. Enough to be detected by telescopes roughly 11 million kilometers away here on Earth. And not any old spacecraft will do when it comes to smashing into Didymos B.
