NASA crashed a high-speed spacecraft into an asteroid and changed it forever

NASA’s Double Asteroid Redirection Test (DART) involved NASA sending a vending machine-sized spacecraft to a binary asteroid system in an attempt to prove the space agency has the capability to redirect potentially dangerous asteroids.

The mission was deemed an overall success as NASA’s high-speed spacecraft collided with the moonlet Dimorphos, which is orbiting a larger asteroid called Didymos. The collision took place on September 26, 2023, and the DART spacecraft reduced the Dimorphos’ orbit around Didymos by 33 minutes, making its total time to complete one orbit around its parent 11 hours and 23 minutes. The success of the mission demonstrated that Earth has planetary defense capabilities to redirect dangerous asteroids years in advance if one is detected.

Now, the DART impact seems to have had a permanent change on the appearance of Dimorphos, as a team of researchers led by University of Bern scientist Sabina Raducan performed high-level computer simulations that determined that Dimorphos is a loose, rubble-pile asteroid. The impact of the DART spacecraft has caused what researchers call global deformation, which is the process of interior material becoming surface material. According to the team’s calculations, between 0.5% and 1% of Dimorphos’ mass was ejected after DART’s impact, with 8% of its mass being redistributed throughout the asteroid.

A simulation of the DART impact on Dimorphos

The material properties and structure of Dimorphos as derived in this study suggests the small moon likely formed through rotational mass shedding and re-accumulation from Didymos,” Raducan said. “These findings offer clues about the prevalence and characteristics of similar binary systems in our solar system, contributing to our broader understanding of their formation histories and evolution.

The implication for planetary defense is that small, rubble-pile asteroids, like Dimorphos, are very efficient to deflect, and the kinetic impactor technique would be an appropriate deflection mechanism,” Raducan said. “However, before attempting deflection, a reconnaissance mission would likely be necessary to accurately assess the asteroid’s properties.