The US space agency picks up a page from science fiction and Hollywood scripts and wants to avoid a collision with Earth.
NASA says it managed to deflect an asteroid in a historic test of mankind’s ability to stop an incoming cosmic object from destroying life on Earth.
The refrigerator-sized Double Asteroid Redirection Test (DART) impactor intentionally slammed into asteroid Dimorphos on September 26, pushing it into a smaller, faster orbit around its big brother Didymos, NASA chief Bill Nelson said.
“DART shortened the orbit from 11 hours and 55 minutes to 11 hours and 23 minutes,” he said. Accelerating Dimorphos’ orbital period by 32 minutes exceeded NASA’s own expectation of 10 minutes.
“We showed the world that NASA means business as a defender of this planet,” Nelson said.
The pair of asteroids orbit the Sun together every 2.1 years and pose no threat to Earth, but they did present an ideal test of the “kinetic impact” method of planetary defense if an actual approaching object is ever spotted.
“In this case there is no risk as this was a deliberately chosen target to ensure this [asteroid crashing on Earth] wouldn’t happen,” Yvette Cende, an astronomer at Harvard University, told Al Jazeera.
DART’s success as a proof-of-concept has turned science fiction into reality.
Astronomers were delighted with stunning images of matter spreading thousands of kilometers after the impact. The images were collected by terrestrial and space telescopes, as well as a satellite that traveled to the zone on DART.
“I grew up watching Armageddon and Deep Impact and all of that and it’s amazing to see this stuff becoming a reality,” Cendes said.
Thanks to its temporary new tail, Dimorphos has transformed into an artificial comet with a diameter of 160 meters (530 feet), or about the size of a great Egyptian pyramid.
But quantifying how well the test worked required analysis of light patterns from ground telescopes, which took a few weeks to become visible.
The binary asteroid system, which was about 11 million kilometers (6.8 million miles) from Earth upon impact, is only visible as a single dot from the ground.
Before the test, NASA scientists said the results of the experiment would show whether the asteroid is a solid rock or more like a “garbage heap” made of boulders bound by mutual gravity.
When an asteroid is more solid, the momentum imparted by a spacecraft is limited. But when it’s “fluffy” and a significant mass is pushed at high speed in the opposite direction of impact, there’s extra thrust.
Never photographed before, Dimorphos appeared as a patch of light about an hour before impact.
Its egg-like shape and jagged, boulder-strewn surface finally came into focus in the final moments as DART hurtled toward it at approximately 23,500 km/h (14,500 mph).
Very few of the billions of asteroids and comets in our solar system are considered potentially dangerous to our planet, and none are expected to impact in the next 100 years or so. But wait long enough and it will happen.
For example, the geological record shows that a 9.6 km (6 miles) wide asteroid struck Earth 66 million years ago, sending the world into a long winter that led to the mass extinction of dinosaurs along with 75 percent of all species.
An asteroid the size of Dimorphos, on the other hand, would only have regional effects, such as devastating a city.
Kinetic impact with a starship is just one way to defend the planet, albeit the only method possible with current technology.