Close-Up Views of NASA’s DART Impact to Inform Planetary Defense

On September 11, 2022, engineers from a flight control center in Turin, Italy sent a radio signal in deep space. Its destination was the spacecraft of the NASA Dart (Double Asteroid Redirection) flying to an asteroid at more than 5 million kilometers.
The message prompted the spaceship to execute a series of preprogrammed commands which caused a small satellite the size of a shoe box contributed by the Italian space agency (ASI), called Liciacube, to detach from DART.
Fifteen days later, when Dart’s journey ended with an intentional frontal collision with almost terrestrial asteroid dimorphos, Liciacube passed the asteroid to take a series of photos, offering researchers the only on -site observations of the first global demonstration of an asteroid deviation.
After having analyzed the images of Licicube, NASA and ASI scientists report on August 21 in the Planetary Science Journal that around 35.3 million pounds (16 million kilograms) of dust and rocks failed asteroid following the accident, refining the previous estimates which were based on data from terrestrial and spatial observations.
Although debris away from the asteroid amounted to less than 0.5% of its total mass, it was still 30,000 times higher than the mass of the spaceship. The impact of debris on the Dimorphos trajectory was dramatic: shortly after the collision, the DART team determined that the flying rubble gave Dimorphos a push several times stronger than the blow of the space machine itself.
“The plume of equipment released from the asteroid was like a short burst of a rocket engine,” said Ramin Lolachi, a researcher who led the study of the NASA Goddard Space Flight Center in Greenbelt, Maryland.
The important point to remember from the DART mission is that a small light spacecraft can considerably modify the path of an asteroid of size and composition similar to the Dimorphos, which is an asteroid “pile of rubble” – or a porous and porous porous collection linked to gravity.
“We expect many asteroids in near land to have a similar structure in Dimorphos,” said Dave Glenar, planetary scientist of Maryland University, in the county of Baltimore, who participated in the study. “Thus, this additional thrust of debris plume is essential to consider when building future spaceships to divert the asteroids of the earth.”

NASA has chosen Dimorphos, which constitutes no threat to the earth, as a target of the mission because of its relationship with another larger asteroid named Didymos. Dimorphos orbit Didymos in a system of binary asteroids, just like the orbitant moon of the earth. Above all, the position of the pair in relation to the earth allowed astronomers to measure the duration of the moon orbit before and after the collision.
Floor and space observations have revealed that the DART shortens the 33 -minute Dimorphos orbit. But these long -range observations, made from 6.8 million miles (10.9 million kilometers), were too far to support a detailed study of the impact debris. It was the work of Liciacube.

After the impact of Dart, Liciacube was only 60 seconds to make his most critical observations. Passing through the asteroid at 15,000 miles (21,140 kilometers) per hour, the spacecraft took an instantaneous debris about once every three seconds. Its closest image was taken at only 53 miles (85.3 km) from the surface of Dimorphos.
The short distance between Licicube and Dimorphos has provided a unique advantage, allowing the cubeat to capture detailed images of dusty debris from several angles.
The research team studied a series of 18 images from Licicube. The first images of the sequence showed the frontal approach of Licicube. From this angle, the plume was brilliantly lit by direct sunlight. While the spacecraft slipped in front of the asteroid, its camera swivel to keep the plume in sight.

While the liciacube looked at the asteroid, the sunlight filtered through the dense debris cloud and the brightness of the plume wasomed. This suggests that the plume was made up of mainly large particles – about a millimeter or more – which reflect less light than tiny dust grains.

Since the deepest parts of the plume were so thick of debris that they were completely opaque, scientists used models to estimate the number of particles hidden at sight. Data from other rubble asteroids of rubble, including Bennu pieces, delivered to the earth in 2023 by the Osiris-Rex spaceship of NASA, and laboratory experiences helped to refine the estimate.
“We estimated that this hidden material represented nearly 45% of the total mass of the plume,” said Timothy Stubbs, a planetary scientist from NASA Goddard who was involved in the study.
While Dart has shown that a high -speed collision with a spacecraft can change the trajectory of an asteroid, Stubbs and its colleagues note that different types of asteroids, such as those made with stronger and tighter materials, can respond differently to an impact of DART. “Whenever we interact with an asteroid, we find something that surprises us, so there is much more work to do,” said Stubbs. “But Dart is a big step forward for the planetary defense.”
Johns Hopkins’ physics laboratory in Laurel, Maryland, managed the Dart mission and operated the spacecraft for the NASA planetary defense coordination office as a project of the agency’s planetary mission program.
By Nathan Marder, nathan.marder@nasa.gov
Goddard Space Flight Center of NASA, Greenbelt, MD.