NASA successfully rammed the DART spacecraft directly into an asteroid this Monday, in a major first for planetary defense strategy (a move predicted in sci-fi movies like Meteor or Don’t Look Up). Yes, it was supposed to crash as hard as possible.

It’s a high point of a NASA project officially called the Double Asteroid Redirection Test, or DART, starting about $300 million and 7 years ago. The craft launched into space in Nov. 2021 from Vandenberg Space Force Base in California, on a one-way mission to test the viability of kinetic impact: Can NASA navigate a spacecraft to hit an asteroid and deflect it to a new course?

Monday’s test suggests the answer is yes.

Scientists chose the Didymos (“twin”) binary system 7 million miles away from the Earth. The asteroid selected for the test poses no actual threat to Earth. It’s a large asteroid orbited by a smaller moonlet named Dimorphos. The system is readily observerable by several Earth-based telescopes, and the predicable orbit makes any deflection by DART easier to measure. The asteroid moonlet is a small body just 530 feet in diameter, about the size of the object that caused Steinheim crater 15 million years ago.

Earth is perpetually bombarded with debris from outer space. Luckily for us, most objects burns up during entry through our atmosphere, and we enjoy a bright trail in the night sky in the form of meteor showers. 

But on occasion, an object is so big it survives its entry through the atmosphere and leaves its mark on the planet, literally. They can be micrometeoroids small as a grain of sand. Or they can be 10 Km wide monsters like the Chicxulub impactor that wiped out the dinosaurs 65 million years ago. This we want to avoid.

The Planetary Defense Coordination Office (PDCO) was created in 2016 as a planetary defense organization within NASA’s Planetary Science Division of the Science Mission Directorate. Their mission is to find, catalog, and develop techniques to stop or mitigate space impactors. The DART is their first mission.

The DART mission is managed by the John Hopkins University Applied Physics Laboratory (JHUAPL), with scientists and engineers from around the world contributing. The craft is about the size and weight of a large refrigerator. It was launched on a SpaceX Falcon 9 and powered by solar panels.

DART deliberately impacted the moonlet Dimorphos at speeds close to 15,00 mph (24,000 kph). Researchers expect DART’s impact to shorten Dimorphos’ orbit around Didymos by about 1%, or 10 minutes per orbit. Investigators will now observe Dimorphos using ground-based telescopes to track the exact trajectory. Like the image showing the explosive impact at top of page.

The Italian Space Agency’s CubeSat for Imaging of Asteroids was deployed from the DART spacecraft two weeks in advance in order to capture images of DART’s impact from nearby. We’ll see more of these images in the coming weeks.

NASA is also developing a new space telescope sentinel called the Near-Earth Object Surveyor specifically designed to seek out hazardous asteroids in the solar system. That mission could launch by 2026.

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