The collision occurred at 7:14 p.m. ET (2314 GMT), 10 months after the Asteroid Double Redirection Test Probe launched from California for its first-of-its-kind experiment.
“We are about to enter a new era, an era in which we will likely have the ability to protect ourselves from something like a dangerous and dangerous asteroid impact,” said Laurie Glaese, director of NASA’s Planetary Science Division.
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The 530-foot (160 m) asteroid Demorphos – roughly comparable to the Egyptian pyramid – orbiting its older brother called Didymus, appeared as a spotlight about an hour before the collision.
The shape of the bun and its rocky surface finally came into play in the last few minutes as DART raced towards it at around 14,500 miles (23,500 km) per hour.
These two asteroids certainly pose no threat to our planet as they orbit the sun, passing about seven million miles from Earth in their current “miniature” location.
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But NASA considered the experiment important before the actual need was discovered.
By hitting Demorphos head-on, NASA hopes to push it into a smaller orbit, flying 10 minutes from the time it takes to encircle Didymus, which is currently 11 hours and 55 minutes — a change that will be detected by ground-based telescopes in the coming days or weeks.
The proof-of-concept experiment will make a reality of what has only been tried before in science fiction — particularly in films like “Armageddon” and “Don’t Look Up.”
Minutes after the collision, a toaster-sized satellite called LICIACube, which had already separated from DART a few weeks ago, was expected to make a pass close to the site to capture images of the impact and ejection — crushed rocks thrown by the hits.
LICIACube images will be sent out in the coming weeks and months.
Watching the action, too: an array of telescopes, both on Earth and in space — including the recently operated James Webb — that might be able to see a bright cloud of dust.
The mission caused an uproar in the global astronomy community, with more than thirty ground-based telescopes taking part, including optical, radio and radar telescopes.
“There are a lot of them, and it’s very exciting to lose track of the number,” said Kristina Thomas, a planetary astronomer for the DART mission.
Finally, a full picture of what the system looks like will be revealed when an ESA mission four years later arrives on the line called Hera to survey the surface of Dimorphos and measure its mass, which for now scientists can only guess at.
Very few of the billions of asteroids and comets in our solar system are considered dangerous to our planet, and none are expected in the next 100 years or so.
But wait too long, and it will happen.
We know that from the geological record – for example, the six-mile-wide asteroid Chicxulub hit Earth 66 million years ago, plunging the world into a long winter that led to the mass extinction of the dinosaurs with 75% of all species.
By contrast, an asteroid the size of Demorphos would only cause a regional impact, such as destroying a city, albeit with more force than any nuclear bomb in history.
How much momentum DART imparts to Demorphos depends on whether the asteroid is solid rock, or more like a “garbage heap” of rock bound by mutual gravity – a property that is not yet known.
If she missed it, NASA will have another shot in a couple of years, with the spaceship containing just enough fuel for another pass.
But its success represents the first step toward a world capable of defending itself from an existential threat in the future.