LAUREL, Md. — It’s the plot of more than one Hollywood blockbuster: A rogue asteroid hurtles toward Earth, threatening tsunamis, mass destruction and the death of every human on the planet.
Humanity has a chance to save itself as brave and selfless heroes pilot a spaceship into the cosmos to destroy the asteroid.
But that’s the way movies are. On Monday night, NASA showed what the reality would look like.
There was an asteroid, but it wasn’t threatening Earth. And there was a spaceship, which relied only on sophisticated technology. The human heroes of the mission were actually in a physics and engineering lab between Baltimore and Washington, DC.
And there was a collision. In this case, it was the final act of the Double Asteroid Redirection Test, or DART, a spacecraft that launched in November and then raced around the sun for 10 months as it chased its target: a small space rock, Dimorphos, to seven million miles away. Land.
“For the first time, humanity has demonstrated the ability to autonomously target and alter the orbit of a celestial object,” said Ralph Semmel, director of the Johns Hopkins University Applied Physics Laboratory, during a news conference after the accident. . The lab managed the mission for NASA.
Hitting an asteroid with a high speed projectile pushes its orbit. For an asteroid headed toward Earth, that might be enough to make a direct hit almost a miss.
In its final moments, the spacecraft sent back a series of photos of the asteroid, Dimorphos, as it approached at more than 14,000 miles per hour.
DART had detected Dimorphos just an hour earlier, as a point of light. Then the celestial debris pile grew larger and larger, until the image of the asteroid’s rock-strewn surface filled the screen. Mission engineers were on their feet, cheering.
“Normally, losing the signal from the spacecraft is a very bad thing,” Dr. Semmel said. “But in this case, it was the ideal result.”
There was one more partial image, but the data never made it back to Earth. DART had crashed into the asteroid.
“Wow, that was amazing, wasn’t it?” said Nancy Chabot, a planetary scientist in the lab working on the mission, during the NASA webcast.
With movies like “Armageddon,” “Deep Impact” and, more recently, “Don’t Look Up,” Hollywood has long been fascinated by the prospect of disaster falling from the cosmos. In recent years, scientists and policymakers have also taken the threat more seriously than ever before.
For many years, lawmakers lacked urgency to fund efforts to protect the planet from asteroids. But that started to change in part because astronomers were able to find all the big asteroids that would wreak destruction across the planet, like the one that wiped out the dinosaurs 66 million years ago, said Thomas Statler, a program scientist on the DART mission. .
Global-scale impacts occur very rarely, about once every 10 million years. But now that possibility has been ruled out, planners at NASA and elsewhere are turning their attention to smaller objects in space. Those are much more numerous and, although they would not cause mass extinctions, they can release more energy than a nuclear bomb.
“The conversation has matured in a really appropriate way,” Dr. Statler said.
The growing focus on planetary defense can be seen in a number of initiatives that NASA and congressional appropriators have sponsored. One is the Vera Rubin Observatory, a new telescope in Chile that is funded by the United States and will painstakingly scan the night sky and find thousands of potentially dangerous asteroids. Another is the NEO Surveyor, a space-based telescope that NASA is working to build. You’ll also find many dangerous asteroids, including some that are difficult to detect from Earth.
If any of those asteroids turn out to be on a collision course with Earth, the DART mission shows that deflecting them is a realistic possibility.
For engineers on the mission, operated by the Johns Hopkins University Applied Physics Laboratory, the impact at 7:14 pm ET marked the end of their work. The spacecraft, which operated autonomously for the last four hours of its existence, successfully locked onto Dimorphos.
That’s even more impressive because the DART camera first spotted Dimorphos just over an hour before impact. Dimorphos orbits a larger asteroid, Didymos, and until then, the smaller asteroid was lost in the glare of the larger object. DART’s navigation system then shifted its gaze to the smaller asteroid.
Up to five minutes before impact, mission controllers could have intervened if something had gone wrong. But they didn’t have to make any adjustments.
For the last five minutes, the people in the control room were also spectators, as was everyone else looking at the torrent of Dimorphos photographs. And then it’s over. Initial analysis indicated that the spacecraft struck about 50 feet from the center of the target.
“I’m definitely relieved,” said Elena Adams, the mission’s systems engineer. “And it’s absolutely wonderful to do something so amazing. And we are very excited to finish.”
For asteroid scientists, their work is just beginning.
By design, the crash occurred when the asteroids were quite close to Earth.
That allowed telescopes on Earth to get a good view. About 40 of them targeted Didymos and Dimorphos, according to NASA and mission managers. So were the Hubble and James Webb Space Telescopes, as was the camera on Lucy, another NASA spacecraft. The LICIACube, a shoebox-sized spacecraft built by the Italian Space Agency, followed DART to take pictures of the impact and debris plume. Its trajectory was shifted to one side so that it would not also collide with the asteroid.
“The rest of us are eagerly anticipating impacts so we can take our science and run with it,” said Cristina Thomas, professor of astronomy and planetary science at Northern Arizona University and leader of the observations working group for the mission. “It’s going to be such a great and exciting once-in-a-lifetime event and we’re putting everything we’ve got into it.”
In the coming days and weeks, Dr. Thomas and other astronomers will sift through the data and images to find out what DART did to Dimorphos. The key measurement will be how much the smaller asteroid, which had been orbiting Didymos every 11 hours and 55 minutes, has accelerated, reflecting how much momentum the spacecraft imparted to the asteroid, causing it to approach Didymos. The change is expected to be around 1 percent, or around seven minutes.
The impact could have given Dimorphos an even bigger boost if the space rock was a pile of debris that had been held together. The DART crash would have created a deep crater and sent a shower of debris into space. That cascade of material would have acted like the thrust of a rocket engine pushing against the asteroid.
Astronomers are looking to see if there is an increase in the brightness of the Didymos-Dimorphos system due to sunlight reflecting off the debris column. Analyzing the specific colors of light could reveal details about the composition of Dimorphos.
A more detailed study will come years later when Hera, a spacecraft being built by the European Space Agency, arrives to take a closer look at the two asteroids, especially the scar made by DART. Scientists estimate that there should be a 30 to 60 foot wide crater.
The pair of asteroids takes two years to go around the sun, and part of the orbit crosses that of Earth. But there is no danger of any of the asteroids hitting Earth any time soon, and the impact had no chance of putting it in Earth’s path.
Still, with a successful demonstration that an asteroid can be deflected, “I think Earthlings should sleep better,” Dr. Adams said. “I definitely will.”