How NASA’s DART mission successfully shifted an asteroid’s orbit for planetary defense

A surprising discovery has been revealed by NASA's DART (Double Asteroid Redirection Test), which aimed to significantly impact the asteroid moonlet Dimorphos. The mission did more than just transform the motion of Dimorphos around its larger companion; the crash also shifted the orbit of both asteroids around the Sun. According to details published in the journal Science Advances, observations of the pair’s motion revealed that the 770-day orbital period around the Sun changed by a fraction after the profound impact.

Analyzing the impact: NASA’s DART strikes Dimorphos

The impact expelled a large amount of debris into space, altering the shape of the asteroid, which measures 560 feet wide. The debris carried its own momentum away from the asteroid, giving Dimorphous an explosive thrust. This phenomenon gives scientists a clue calling the momentum enhancement factor. The new research suggests that the momentum enhancement factor for DART’s impact was about two, underscoring that the ejected debris loss doubled the punch created by the spacecraft.

In this connection, the study’s lead author at the University of Illinois Urbana-Compaign said: “The change in the binary system’s orbital speed was about 11.7 per second, or 1.7 inches per hour.”

This intriguing study of the changes in Didymos’ motion also helped the researchers to calculate the internal density structure of both asteroids. Dimorphos is slightly denser than previously estimated, supporting the theory that it formed from rocky debris shed by a rapidly spinning Didymos.

The DART spacecraft was designed and operated by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland on behalf of NASA’s Planetary Defence Coordination Office which oversees the agency's efforts in planetary defense. Furthermore, this groundbreaking discovery stems from humanity’s first mission to internationally move a celestial object, offering a unique perspective for the scientific community and the public alike.