On September 26, 2022, NASA intentionally crashed their DART spacecraft into the asteroid Dimorphos, with the goal of altering the trajectory of the asteroid by transferring the momentum of the spacecraft to the asteroid. The asteroid itself is a satellite of the much larger asteroid, Didymos. DART impacted Dimorphos head-on in the direction opposite the asteroid’s orbital direction, causing its overall orbital velocity to decrease. The primary goal of DART was to determine the feasibility of changing the trajectory of an asteroid, with the hope that humanity will have the means to deflect potentially dangerous asteroids.
Impacting an Asteroid
DART was launched by NASA on November 24, 2021. The spacecraft was accompanied by another craft called LICIACube, supplied by the Italian Space Agency, and separated from DART just 15 days before impact. LICIACube remained in orbit around the asteroid and took photographs of the impact and material ejected from the asteroid’s surface.
Threat of Asteroid Impacts
Asteroids can pose a significant threat to planet Earth. Small asteroids can potentially damage small areas, while larger asteroids have the potential of causing extinction level events. For example, around 66-million years ago, an asteroid around 6 to 9 miles across (10 to 15 kilometres) struck the Earth in what is now the Yucatan Peninsula. The resulting impact was so catastrophic that it caused one of the largest extinction events in Earth history, wiping out over 70% of all life on Earth, including all non-avian dinosaurs. Asteroid impacts of this magnitude do not happen often; scientists estimate extinction level asteroid impacts occur every 100-million years. However, there are likely thousands of asteroids that have yet to be discovered, and there is always a small chance that there are potentially dangerous asteroids in our solar system that have not yet been discovered. With this in mind, agencies like NASA have dedicated significant resources to studying and tracking asteroids, as well as looking for those that might pose a threat to life on Earth. With DART, NASA successfully altered the trajectory of an asteroid, a method that would need to be utilized in the event that an asteroid is heading directly towards the Earth. Although movies and films have popularized the idea that an incoming asteroid could simply be blown apart, it is very unlikely that this would prevent a direct impact. Rather, the best way to prevent an asteroid impact would be to redirect the asteroid on a trajectory that causes it to move past our world.