The Goal: Planetary Defense Through Kinetic Impact
DART was the first mission specifically designed to demonstrate the "kinetic impactor" technique for asteroid deflection. This method involves deliberately crashing a spacecraft into an asteroid to alter its trajectory ever so slightly. Even a small nudge applied well in advance can significantly change an asteroid's path over time, potentially preventing a future collision with Earth.
The Target: The Didymos System
DART set its sights on a binary asteroid system called Didymos. The larger asteroid, Didymos, has a smaller moonlet named Dimorphos orbiting it. DART targeted Dimorphos, the 530-foot (160-meter) moon, while Didymos itself measures 2,560 feet (780 meters) across.
The Journey: Launch, Cruise, and Separation
Launched aboard a SpaceX Falcon 9 rocket, DART used an electric thruster to gain the necessary speed for its deep space voyage. The spacecraft also carried a high-resolution camera called DRACO for navigation and capturing the impact. Interestingly, DART might have flown past another asteroid, 2001 CB21, during its journey.
In September 2022, DART deployed a small Italian spacecraft called LICIACube. This CubeSat companion would act as an independent observer, capturing images of the collision and its aftermath from a unique vantage point.
The Impact: A resounding success
On September 26, 2022, DART bravely slammed into Dimorphos at a relative speed of approximately 14,000 miles per hour (22,500 kilometers per hour). This impact successfully altered the moonlet's orbit around Didymos by an impressive 33 minutes, demonstrating the effectiveness of the kinetic impact technique.
The Legacy: Paving the Way for Future Missions
The DART mission is a significant milestone in planetary defense. It has proven that humanity has the potential to deflect a threatening asteroid, should the need ever arise. The data and insights gleaned from DART will be crucial for developing and refining asteroid deflection strategies for the future.
Beyond DART: The Hera Mission
The European Space Agency (ESA) has a follow-up mission called Hera planned for launch in 2024. Hera is expected to rendezvous with the Didymos system in late 2026 to study the impact crater left by DART on Dimorphos and measure the mass of the moonlet more precisely. This combined effort between NASA and ESA will significantly enhance our understanding of asteroid deflection techniques.