Humanity has achieved a groundbreaking feat by successfully altering the orbit of an asteroid around the sun for the first time. This remarkable accomplishment was made possible by NASA’s Double Asteroid Redirection Test (DART) mission in 2022, with the effects of the mission recently being quantified.
The target of the DART mission was Dimorphos, a small asteroid that orbits a larger one named Didymos. By crashing into Dimorphos, the spacecraft aimed to shift its orbit around Didymos, testing the efficacy of a kinetic impactor in changing an asteroid’s trajectory to avert potential threats to Earth.
The mission yielded impressive results, with Dimorphos’s orbit being shortened by 32 minutes. Over the years, astronomers have closely monitored the system, conducting nearly 6000 observations to determine the overall change in the pair’s orbit around the sun. The orbital speed has decreased by 11.7 micrometres per second, equivalent to around 40 millimetres per hour, which is projected to reduce the radius of the orbit by approximately 360 metres.
Rahil Makadia from the University of Illinois Urbana-Champaign, part of the asteroid orbit monitoring team, explains that while the numerical changes may seem small, the cumulative impact of early interventions can lead to significant alterations over time. The slowdown resulted from both the initial spacecraft impact and the subsequent push from the debris ejected from Dimorphos’s surface. This allowed researchers to calculate the masses and densities of the asteroids, revealing that Dimorphos is less dense than Didymos, suggesting it may have formed from materials ejected from Didymos due to its rotation.
The insights gained from this mission will be invaluable in potential future asteroid deflection scenarios. Makadia emphasizes the importance of this data as a foundation for predicting and executing future kinetic impact missions. Additionally, the European Space Agency’s Hera spacecraft, en route to Didymos and expected to arrive in November, will provide further precise measurements to enhance our understanding and guide future asteroid deflection strategies to safeguard Earth from potential threats.
