The DART mission is about to collide with an asteroid
The Double Asteroid Redirection Test mission, or DART, aims to see if this kind of kinetic impact can help deflect an asteroid posing a threat to Earth.
“We are moving an asteroid,” said Tom Statler, NASA program scientist for the DART mission. “We are changing the motion of a natural celestial body in space. Humanity has never done that before.”
Here’s what you need to know about this mission.
The DART spacecraft is about the size of a school bus. It has been traveling to reach its asteroid target since launching in November 2021. The spacecraft will arrive at the asteroid system on September 26. Impact is expected at 7:14 p.m. ET.
Where is it going?
The spacecraft is heading for a double-asteroid system, where a tiny “moon” asteroid, named Dimorphos, orbits a larger asteroid, Didymos.
Didymos. which means “twin” in Greek, is roughly 2,560 feet (780 meters) in diameter. Meanwhile, Dimorphos measures 525 feet (160 meters) across, and its name means “two forms.”
At the time of impact, Didymos and Dimorphos will be relatively close to Earth — within 6.8 million miles (11 million kilometers).
Neither Dimorphos nor Didymos is at risk of colliding with Earth — before or after the collision takes place.
What will DART do?
DART is going down in a blaze of glory. It will set its sights on Dimorphos, accelerate to 13,421 miles per hour (21,600 kilometers per hour) and crash into the moon nearly head-on.
The spacecraft is about 100 times smaller than Dimorphos, so it won’t obliterate the asteroid.
Instead, DART will try to change the asteroid’s speed and path in space. The mission team has compared this collision to a golf cart crashing into one of the Great Pyramids — enough energy to leave an impact crater.
The impact will change Dimorphos’ speed by 1% as it orbits Didymos. It doesn’t sound like much, but doing so will change the moon’s orbital period.
The nudge will shift Dimorphos slightly and make it more gravitationally bound to Didymos — so the collision won’t change the binary system’s path around the Earth or increase its chances of becoming a threat to our planet.
What will we get to see?
The spacecraft will share its view of the double-asteroid system through an instrument known as the Didymos Reconnaissance and Asteroid Camera for Optical navigation, or DRACO.
This imager, which serves as DART’s eyes, will allow the spacecraft to identify the double-asteroid system and distinguish which space object it’s supposed to strike.
Didymos and Dimorphos will appear as pinpricks of light about an hour before impact, gradually growing larger and more detailed in the frame.
Dimorphos has never been observed before, so scientists can finally take in its shape and the appearance of its surface.
We should be able to see Dimorphos in exquisite detail before DART crashes into it. Given the time it takes for images to stream back to Earth, they will be visible for eight seconds…
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