DART mission: How NASA hit the eye

Small asteroids hit Earth’s atmosphere every single day. It’s the big ones we care about, as depicted in such Hollywood extravaganzas as “Armageddon” and “Don’t Look Up.”

“I’ve never been able to sit still and watch any of the asteroid movies and not just want to get up and walk away,” said MIT professor Richard Binzel. Besides writing the book on asteroids, he also invented the Turin scale, a 10-point danger scale for asteroids.

“All the objects we know of today are at zero or one, which simply means that they are so small that they don’t matter, or that we know for sure that there is no possibility of impact,” Binzel said .


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Correspondent David Pogue asked, “Sounds like asteroids wiping out humanity shouldn’t be at the top of our list of concerns?”

“Asteroids wiping out our humanity don’t keep me up at night unless I’m at the telescope studying them!” Binzel laughed.

But there have been dangerous asteroid strikes. In 2013, a 60-foot rock from space injured 1,500 people and damaged thousands of buildings in Russia.

NASA believes it’s time to prepare for the next one.

But probably not the way an asteroid was dealt with in “Deep Impact” — by blowing it up.

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“It is enough does not the best way to do it,” said NASA’s Elena Adams. “Because if you blow up an asteroid, you create a large number of chunks. And those bits will still go in the same direction. The easiest thing to do is actually just change its direction slightly and then it will miss the Earth completely.”

Adams is the lead engineer on the DART mission, a joint venture between NASA and the Johns Hopkins Applied Physics Laboratory. It took off last November on a mission to alter an asteroid’s path by crashing into it.

DART stands for Double Asteroid Redirection Test because its target is actually a double asteroid orbiting the sun. The main asteroid, called Didymos, is about half a mile across. It has its own moon and that is our goal.

An illustration of NASA’s Double Asteroid Redirection Test (DART) spacecraft prior to impact with Dimorphos, a 525-foot-wide moon in the Didymos binary asteroid system.

NASA/Johns Hopkins APL/Steve Gribben

The goal is to bump the lunar light’s orbit a little closer to Didymos. “Just a little nudge, a tap,” Adams said. “It’s basically like throwing a tennis ball at a 747. If it goes fast enough, you move it. This is a first test of, can we actually do that?”

As a bonus, the 1,200-pound spacecraft is a veritable science fair of technology tests that could be useful in future missions: superlight solar panels that roll out; a new ion thruster; and a separate small camera satellite that DART carried in its pocket, the Italian Space Agency’s LICIAcube, so we can all enjoy images of the crash.

There’s even a new self-driving computer, SMART Nav, which takes over when DART is too far away to control from Earth

“This is the crown jewel of the spacecraft,” Adams said. “So we’ll see how well it works.”

DART is the first major project of a NASA department called the Planetary Defense Coordination Office.

NASA’s Lori Glaze heads the division that oversees planetary defense.

“The ones that are truly civilization-ending-sized asteroids, we know; we’ve already found 99% of them,” Glaze said. “The smaller ones that might have regional damage, there are some out there that we don’t know about. So we’re actually already building the next telescope, a space telescope called the Near-Earth Object Surveyor (NEO Surveyor) ) to search the sky 24 hours a day.”

This past Monday, 10 months after launch, DART approached its goal: seven million miles from Earth, traveling four miles per second, toward an asteroid moon no one has ever seen.

And to make things even more difficult? Adams said, “We also don’t know what it’s made of, we don’t know its shape. How do you hit something where you don’t even know its shape?”

At 19 minutes until impact, you could see the moonlight Dimorphos for the first time.

Dimorphos, just before impact.

NASA/Johns Hopkins APL

NASA’s DART hit in the head.

The Italian Space Agency’s LICIACube captured this image of the DART spacecraft hitting the small moon Dimorphos orbiting Didymos on September 26, 2022.


In a few weeks, NASA will calculate how much the little moon moved. But we already know what happened to Elena Adams’ $325 million baby. “It’s like a Ferrari, isn’t it? It’s just a beautiful piece of equipment, and the whole point of it is to smash into a rock!” she laughed.

“That’s sad!” Pogue said.

“But also a bit glorious!”

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Story produced by Julie Kracov. Editor: Mike Levine.

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