The galactic battle took place on a harmless asteroid 7 million miles (9.6 million kilometers) away, with the spacecraft named darts plowing into the space rock at 14,000 mph (22,500 kph). Scientists expected the impact would carve out a crater, send streams of rocks and debris into space and, most importantly, alter the asteroid’s orbit.
“We have influence!” Elena Adams of Mission Control announced, jumping up and down and reaching for the sky.
Telescopes around the world and in space aim at the same point in the sky to capture the spectacle. While the impact was immediately apparent — Dart’s radio signal stopped abruptly — it will take days or even weeks to determine how much the asteroid’s path has changed.
“Now the science begins,” said NASA’s Lori Glaze, director of the planetary science division. “Now we’re really going to see how effective we were.”
The $325 million mission was the first attempt to change the position of an asteroid or other natural object in space.
“What an amazing thing. We’ve never had that opportunity before,” Glaze commented.
Earlier in the day, NASA administrator Bill Nelson reminded people via Twitter, “No, this is not a movie plot.” He added in a pre-recorded video: “We’ve all seen it in movies like ‘Armageddon,’ but in real life there’s a lot at stake.”
Monday’s target: a 160-meter asteroid called Dimorphos. It’s actually a moon of Didymos, Greek for twin, a fast-spinning asteroid five times larger that hurled off the material that formed the junior partner.
The pair have orbited the sun for eons without threatening the Earth, making them ideal test candidates for saving the world.
Launched last November, the vending machine-sized Dart — short for Double Asteroid Redirection Test — navigated to its target using new technology developed by the Johns Hopkins University Applied Physics Laboratory, the spacecraft builder and mission manager.
Dart’s built-in camera, an important part of this smart navigation system, saw Dimorphos barely an hour before the collision.
“Woo hoo,” exclaimed Adams, a mission systems engineer at Johns Hopkins. “We see Dimorphos, so amazing, amazing.”
With an image beaming to Earth every second, Adams and other ground controllers in Laurel, Maryland, watched with growing excitement as Dimorphos loomed larger and larger in the field of view alongside his larger companion. Within minutes, Dimorphos was alone in the photos; it looked like a giant gray lemon, but with boulders and debris on the surface. The last image froze on the screen as the radio broadcast ended.
Flight controllers cheered, hugged and exchanged high fives. Their mission was completed, the Dart team went straight into party mode. There was no grief over the demise of the spacecraft. “It’s meeting its fate,” said Betsy Congdon, the mechanical leader of Johns Hopkins.
A mini-satellite followed a few minutes behind to take pictures of the impact. The Italian Cubesat came out of Dart two weeks ago.
Scientists insisted that Dart not shatter Dimorphos. The spacecraft weighed a whopping 1,260 pounds (570 kilograms), compared to the asteroid’s 11 billion pounds (5 billion kilograms). But that should be enough to narrow its 11-hour 55-minute orbit around Didymos.
The impact should be 10 minutes from there, but telescopes need a few days to nearly a month to verify the new orbit. The expected 1% orbital shift may not sound like much, scientists noted. But they emphasized that it would amount to significant change over the years.
Planetary defense experts prefer to push an impending asteroid or comet out of the way, with enough lead time, rather than blow it up and create multiple pieces that could rain on Earth. Multiple impactors may be needed for large space rocks or a combination of impactors and so-called gravity tractors, not yet invented devices that would use their own gravity to pull an asteroid into a safer orbit.
“The dinosaurs didn’t have a space program to help them know what was coming, but we did,” NASA’s senior climate adviser Katherine Calvin said, referring to the mass extinction thought to have been caused by a major asteroid impact 66 million years ago. volcanic eruptions or both.
The nonprofit B612 Foundation, which is committed to protecting Earth from asteroid impacts, has been pushing for impact tests like Dart since its inception by astronauts and physicists 20 years ago. Aside from Monday’s feat, the world needs to better identify the myriad space rocks that lurk there, warned the foundation’s executive director, Ed Lu, a former astronaut.
According to NASA, significantly less than half of the estimated 25,000 near-Earth objects in the lethal range of 140 meters have been discovered. And less than 1% of the millions of smaller asteroids, which can cause widespread injuries, are known.
Nearly completed by the National Science Foundation and the US Energy Department in Chile, the Vera Rubin Observatory promises to revolutionize asteroid discovery, Lu noted.
Finding and tracking asteroids: “That’s still the name of the game here. That’s what needs to be done to protect Earth,” he said.