NASA’s DART spacecraft deliberately collided with an asteroid on Monday to deflect it from its trajectory, an unprecedented test to find mechanisms to defend the Earth from a devastating collision of a cosmic object.
The ship, smaller than a car, crashed at more than 20,000 kilometers per hour against its target. NASA teams, gathered at mission control in Maryland, burst with happiness at the spectacular images of the approaching asteroid until shortly before impact.
But the mission, called DARTshould “help determine our response if we detect an asteroid threatening to hit Earth” in the future, NASA chief Bill Nelson said Monday.
The moment of impact, 11 million kilometers from Earth, has been followed live on the NASA channel.
“We are changing the motion of a natural celestial body in space, humanity has never done this before,” said Tom Statler, chief scientist for the mission. “It’s something out of science fiction books and Star Trek episodes from when I was a kid. And now it’s real.”
The target is actually a pair of asteroids: a large one, Didymos (780 meters in diameter), and its satellite, Dimorphos (160 meters in diameter), in orbit around it. The two are only a kilometer apart.
Dymorphos currently revolves around the larger one in 11 hours and 55 minutes. What is sought is to reduce its orbit in about 10 minutes. This change can be measured with telescopes on Earth, observing the variation in brightness when the small asteroid passes in front of the large one.
When will we know if it worked? “I’d be surprised if we had hard evidence in less than a few days, and I’d be surprised if it took more than three weeks,” Statler said.
IMPACT SUCCESS! Watch from #DARTMIssion’s DRACO Camera, as the vending machine-sized spacecraft successfully collides with asteroid Dimorphos, which is the size of a football stadium and poses no threat to Earth. pic.twitter.com/7bXipPkjWD
— NASA (@NASA) September 26, 2022
Meanwhile, on Monday, the spacecraft’s built-in camera, called DRACO, will take one image per second. These images will reach Earth with a delay of only about 45 seconds.
To hit such a small target, the spacecraft has been steered autonomously for the past four hours, like a homing missile.
He first targeted the largest body, Didymos, before Dimorphos appeared. The small asteroid, never before seen in images before filling the entire field of view.
The approximately forty people present in the control room of the Applied Physics Laboratory (APL) at Johns Hopkins University in Maryland were prepared to intervene if necessary, if they had to make any corrections.
Three minutes later, a shoebox-sized satellite called LICIACube launched by DART A few days ago, it will pass within 55 km of the asteroid to capture images of the collision, which will be sent to Earth in the coming weeks and months.
The event has also been observed by the Hubble and James Webb Space Telescopes, which should be able to detect a bright cloud of dust.
All this should allow a better understanding of the composition of Dimorphos, representative of a fairly common population of asteroids, and therefore measure the effect that this technique, called kinetic impact, can have on them.
Asteroids have surprised scientists in the past. In 2020, the American Osiris-Rex probe sank much deeper than expected to the surface of the asteroid Bennu.
The porosity of Dimorphos is currently unknown. “If the asteroid responds to the impact of DART in a totally unforeseen way, it could actually lead us to reconsider the extent to which impact kinetics is a generalizable technique,” Statler said.
None of the known asteroids threaten Earth for the next 100 years.
Nearly 30,000 asteroids of all sizes have been cataloged in its vicinity, which it calls near-Earth objects, that is, its orbit crosses the Earth’s orbit.
Those of a kilometer or more have been sighted almost all, according to scientists. But they estimate that they only know about 40% of the asteroids that measure 140 meters or more, capable of devastating an entire region.
“Our most important job is to find” the missing ones, said Lindley Johnson, NASA’s planetary defense agent.
The earlier they are detected, the more time experts have to determine the best way to defend against them.
but the mission DART it’s a crucial first step, Johnson said: “It’s a very exciting time … for space history, and even for human history.”