STScI: Hubble Sees Boulders Escaping from Asteroid Dimorphos

This Hubble Space Telescope image of the asteroid Dimorphos was taken on December 19, 2022, nearly four months after the asteroid was impacted by NASA’s DART mission (Double Asteroid Redirection Test). Hubble’s sensitivity reveals a few dozen boulders knocked off the asteroid by the force of the collision. These are among the faintest objects Hubble has ever photographed inside the solar system. The free-flung boulders range in size from three feet to 22 feet across, based on Hubble photometry. They are drifting away from the asteroid at a little more than a half-mile per hour. The discovery yields invaluable insights into the behavior of a small asteroid when it is hit by a projectile for the purpose of altering its trajectory. Credits: NASA, ESA, David Jewitt (UCLA)

The popular 1954 rock song “Shake, Rattle and Roll,” could be the theme music for the Hubble Space Telescope’s latest discovery about what is happening to the asteroid Dimorphos in the aftermath of NASA’s DART (Double Asteroid Redirection Test) experiment. DART intentionally impacted Dimorphos on September 26, 2022, slightly changing the trajectory of its orbit around the larger asteroid Didymos.

Astronomers using Hubble’s extraordinary sensitivity have discovered a swarm of boulders that were possibly shaken off the asteroid when NASA deliberately slammed the half-ton DART impactor spacecraft into Dimorphos at approximately 14,000 miles per hour.

The 37 free-flung boulders range in size from three feet to 22 feet across, based on Hubble photometry. They are drifting away from the asteroid at little more than a half-mile per hour – roughly the walking speed of a giant tortoise. The total mass in these detected boulders is about 0.1% the mass of Dimorphos.