A NASA spacecraft rammed an asteroid at breakneck speed on Monday in an unprecedented dress rehearsal for the day a killer rock threatens Earth.
The galactic impact occurred on a harmless asteroid 9.6 million kilometers away, with the spacecraft dubbed Dart plowing into space rock at 22,500 km/h. Scientists expected the impact to carve out a crater, eject streams of rock and dirt into space, and most importantly, alter the asteroid’s orbit.
“We have influence!” proclaimed Elena Adams of Mission Control, jumping up and down and raising her arms skyward.
Telescopes around the world and in space aimed at the same point in the sky to capture the spectacle. Although the impact was immediately apparent – Dart’s radio signal cut off abruptly – it will take days or even weeks to determine just how much the asteroid’s orbit has changed.
Infographic showing the size of the two asteroids in the Didymos system in relation to some objects on Earth.
NASA/Johns Hopkins APL
The $325 million mission was the first attempt to shift the position of an asteroid or other natural object in space.
“We are entering a new era for humanity,” said Lori Glaze, director of NASA’s Division of Planetary Sciences.
Earlier in the day, NASA Administrator Bill Nelson reminded people via Twitter, “No, this isn’t a movie plot.” He added in recorded video, “We’ve all seen it in movies like ‘Armageddon,’ but in real life there is a lot at stake.”
The target on Monday: a 160 meter high asteroid called Dimorphos. It’s actually a small moon of Didymos, Greek for Gemini, a rapidly spinning asteroid five times larger that ejected 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 machine-sized dart — short for Double Asteroid Redirection Test — navigated to its target using new technology developed by Johns Hopkins University’s Applied Physics Laboratory, the spacecraft builder and mission manager.
Dart’s onboard camera, an important part of this intelligent navigation system, spotted Dimorphos just under an hour before impact.
“Woo hoo,” exclaimed Adams, a mission systems engineer at Johns Hopkins. “We see Dimorphos, so wonderful, wonderful.”
As an image was beamed back to Earth every second, Adams and other ground controllers in Laurel, Maryland, watched with growing excitement as Dimorphos grew larger and larger into view alongside its larger companion. Within minutes Dimorphos was alone in the pictures; it looked like a huge gray lemon, but with boulders and debris on the surface. The last image froze on the screen as the radio transmission ended.
Air traffic controllers cheered, hugged and exchanged high fives.
A minisatellite followed a few minutes later to take photos of the impact. The Italian Cubesat was released by Dart two weeks ago.
Scientists insisted that Dart would not break Dimorphos. The spacecraft weighed a scant 1,260 pounds (570 kilograms) compared to the asteroid’s 11 billion pounds (5 billion kilograms). But that should be enough to shorten its 11 hour and 55 minute orbit around Didymos.
The impact should be 10 minutes shorter, but telescopes will take a few days to almost a month to check the new orbit. The expected 1% orbital shift may not sound like much, the scientists noted. However, they emphasized that this would lead to a significant change over the years.
Planetary defense experts prefer to shove a menacing asteroid or comet out of the way with enough lead time rather than blowing it up and creating multiple bits that could rain down on Earth. Large space rocks might require multiple impactors or a combination of impactors and so-called gravity tractors, devices not yet invented 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,” said NASA senior climate adviser Katherine Calvin, referring to the mass extinction believed to have occurred 66 million years ago that it was caused by a large asteroid impact, volcanic eruptions, or both.
The nonprofit B612 Foundation, dedicated to protecting Earth from asteroid impacts, has been pushing for impact tests like darts since it was founded by astronauts and physicists 20 years ago. Aside from Monday’s performance, the world needs to better identify the myriad space rocks lurking out there, warned the foundation’s executive director Ed Lu, a former astronaut.
Significantly fewer than half of the estimated 25,000 near-Earth objects within the lethal range of 140 meters have been spotted, according to NASA. And less than 1% of the millions of smaller asteroids that can cause widespread injury are known.
The Vera Rubin Observatory, which is nearing completion in Chile by the National Science Foundation and the US Department of Energy, promises to revolutionize the field of asteroid discovery, Lu noted.
Finding and Tracking Asteroids: “That’s still the name of the game here. This has to happen to protect the earth,” he said.
