Published March 2, 2024 at 4:18 p.m.
Updated March 2, 2024 at 4:20 p.m.
The asteroid Dimorphos weighs one million tons. NASA hit it so hard that it lost 10,000 tons and changed shape.
Planetary Defense
Last September, NASA's Double Asteroid Redirection Test (DART) mission tested a method of planetary defense by hitting the asteroid Dimorphos to throw it off course. NASA researchers wanted to test the feasibility of this process to potentially deflect asteroids whose trajectory could cross Earth's.
A different trajectory
NASA's probe hit the asteroid at a speed of 15,000 miles per hour, changing its trajectory by more than half a degree. Half a degree may not seem like much, but at a distance of, say, a million kilometers, or less than three times the distance between the Earth and the Moon, such a deviation would correspond to a difference of more than 10,000 km. So this would be enough for a dangerous asteroid to avoid our planet.
A colossal effect
But that's not all. Investigations with complex simulations then produced a surprising result. The impact not only changed the asteroid's trajectory, but also changed its shape. Between 0.5% and 1% of its mass was ejected and 8% was redistributed, giving it a new appearance. In a few years, the European Space Agency's Hera mission will visit Dimorphos and may be able to confirm these data. Another step towards planetary defense against possible asteroid impacts on Earth.