NASA’s DART Mission Punches a Killer Asteroid to Save Humanity

Because Dimorphos is such a small space rock, DART will have to hit hard once the asteroid system reaches its closest point to Earth during its orbit around the sun, about 6.8 million miles away. This is a complex orbital choreography that will improve DART’s collision path with Dimorphos, with a precise launch time from Earth and intermittent firings of a dozen small onboard thrusters.

“In terms of engineering, it’s really tough,” said Andy Rivkin, DART research team leader at the Johns Hopkins Applied Physics Laboratory, who led the mission. DART’s only shot at the stunning Dimorphos will be based on a fully automated process that starts four hours before impact and uses an onboard navigation system called SMART Nav.

“They needed to create an algorithm that does this on its own; There is no need to put a joystick in it,” he said.

Tom Statler, a DART program scientist at NASA, agrees.

“In a way, DART is pretty simple. There is only one instrument on board,” he said, referring to the spacecraft’s camera. “But on the other hand, the precision of the navigation is really beyond what we’ve done before.”

Ten days before the collision, DART will deploy a small satellite called LICIACube, built by the Italian Space Agency and carrying two cameras. This companion will witness DART’s self-destructing mission from 34 miles away and measure the amount of debris from the collision. The DART spacecraft’s onboard camera, called DRACO, will take pictures of the asteroid as it approaches and send them back to Earth up to 20 seconds before impact.

To test whether DART is successful, scientists at NASA and the Applied Physics Laboratory will measure how much Dimorphos’ orbit around Didymos has changed after the spacecraft crashed. For ground-based telescopes, asteroids are tiny points of light. After the collision, the scientists will track the duration of Dimorphos’ orbit by measuring the time between flickers of reflected light, which indicates that Dimorphos passed in front of Didymos and then half an orbital later.