NASA succeeded in changing asteroid's orbit around sun in world's first

Humanity has successfully altered an asteroid’s orbit around the Sun for the first time, according to new measurements from an earlier NASA mission, though it might have occurred unintentionally.

During NASA's Double Asteroid Redirection Test (DART) mission carried out in 2022, the agency deliberately crashed its spacecraft into the small asteroid Dimorphos, which orbits the larger asteroid Didymos. A new study has now shown that the impact not only altered the moonlet’s orbit around Didymos but also slightly changed the pair’s overall path around the Sun.

The spacecraft was intentionally directed into the smaller asteroid to test whether a technique known as a kinetic impactor could shift an asteroid’s trajectory. Such a method could potentially be used in the future to deflect an asteroid on a collision course with Earth.

The mission proved highly successful. The collision shortened Dimorphos’s orbit around Didymos by 32 minutes. Since then, astronomers have continued monitoring the asteroid system, gathering nearly 6,000 observations. These measurements show that the pair’s overall orbit around the Sun slowed by about 11.7 micrometres per second—roughly 40 millimetres per hour—reducing the radius of their orbit by an estimated 360 metres.

“It doesn’t sound like a lot, but the whole idea behind these kinetic impacts is that if you do one early enough, a small impact makes a large change in the overall position,” said Rahil Makadia of University of Illinois Urbana-Champaign, a member of the team studying the asteroids’ motion. “It’s a very tiny number, but if you let it accumulate over decades, then it can grow into a big one.”

Researchers say the slowdown resulted from two factors: the initial spacecraft impact and a secondary push from a plume of debris ejected from Dimorphos’s surface after the collision. Makadia and his colleagues found that both effects contributed roughly equally.

These measurements also helped scientists estimate the masses and densities of the two asteroids. Dimorphos appears to be about half as dense as Didymos, supporting the theory that it is a “rubble pile” asteroid formed from material thrown off Didymos due to its rotation.

Scientists say the findings will be valuable if humanity ever needs to deflect a dangerous asteroid. “We now have one solid anchoring point to predict any future kinetic impact missions,” Makadia said.

Further insights may come soon from the European Space Agency’s Hera mission spacecraft, which is currently travelling to the Didymos system and is expected to arrive in November. The probe will study the aftermath of the DART impact in detail and help refine future strategies for protecting Earth from potentially hazardous asteroids.

By Nazrin Sadigova