Breakthrough in NASA’s ability to prevent asteroid impacts on Earth

CAPE CANAVERAL. An asteroid that NASA used as a target practice a few years ago has been diverted to a slightly different path around the sun, which could help deflect a future deadly space rock, scientists reported Friday.

It is the first time that the orbit of a celestial body around the Sun has been deliberately modified. The asteroid that the probe impacted Dart NASA never posed a threat to Earth.

“This study marks a notable advance in our ability to prevent future asteroid impacts on Earth,” the international research team wrote in Science Advances.

The changes were slight: reductions of just a tenth of a second and 720 meters in a solar return spanning two years and hundreds of millions of kilometers, according to scientists.

“While this may seem small, a small deviation… can accumulate over decades and make the difference between a potentially dangerous asteroid hitting Earth in the future or not,” lead author Rahil Makadia of the University of Illinois at Urbana-Champaign said in an email.

In any attempt to save the planet, “the key is not to give a huge push at the last minute, but to give a small one many years in advance,” he added.

Launched in 2021 during the world’s first planetary defense exercise, the probe Dart deliberately crashed into Dimorphos, which orbits a larger asteroid, Didymos, as they orbit the Sun together. The space agency quickly determined that the 2022 impact clipped the smaller asteroid’s orbit around its larger companion.

But so far, scientists have not confirmed, based on observations from around the world, that the impact reduced the duo’s travel time around the Sun by 0.15 seconds. Given that each solar orbit lasts 769 days, this represents a real-time deceleration of just over 10 micrometers per second, which reduces the orbit of the asteroids from 480 million kilometers by 720 meters.

The researchers claimed that the rocks and other debris ejected from Dimorphos in the impact provided it with as much thrust as the spacecraft itself, doubling its momentum. Last summer, an American-Italian team estimated that 16 million kilograms of rock and dust were ejected.

The good news is that even with the asteroids changing course, Earth remains safe from their trajectory for the foreseeable future. That’s why this debris-filled system was selected for the mission, according to Steven Chesley of NASA’s Jet Propulsion Laboratory, who participated in the study.

“While this is just an experiment, it is an important piece of information that will be relevant to any future asteroid detour missions,” Chesley said in an email.

Scientists hope to learn even more about the consequences of the impact when the probe Hera of the European Space Agency reaches the asteroids in November. Dimorphos is 160 meters in diameter. The rapidly rotating Didymos is 780 meters in diameter and, according to the latest study, has a mass 200 times that of its companion.

Unlike Dart, Hera It will not attack, but will stay with us for months of exploration. A pair of small experimental probes will separate and attempt to land.