Buried in the dirt across the globe is a thin layer of dust sprinkled with iridium, a silvery-white metal abundantly found in asteroids. This is the Cretaceous–Paleogene boundary, which is some of the most solid evidence we have that a giant space rock wiped out all of the non-avian dinosaurs 66 million years ago. The impact was so massive and deadly, it killed off 75% of all animals and plants on Earth, leaving behind a scar that persists today.
Such a devastating collision could happen again — and with equally catastrophic extinction. Would humans be prepared if a comet or meteor was suddenly aimed right at us? We can't know until it happens.
In fact, the president of the B612 Foundation, a nonprofit foundation dedicated to planetary defense, has said there's a 100% chance of Earth getting hit by an asteroid at some point. We just don't know when.
Thankfully, some smart individuals have been trying to prepare for this scenario, which could one day save humans from joining the dinosaurs in the dustbin of history.
As Salon's Matthew Rozsa previously reported, real-life NASA engineers were "acutely concerned about the threat of space rocks ending life as we know it." To that end, NASA launched the spacecraft "to test means of neutralizing such a threat, using methods similar to (but not exactly like) those seen in the 1998 big-budget asteroid disaster movies 'Armageddon' and 'Deep Impact.'"
Today, we got the first glimpse of what a future planetary defense program would look like in real life. At 7:14 p.m. ET on Sept. 26, a space probe called the Double Asteroid Redirection Test (DART) crashed into an asteroid at 14,000 mph, or just under four miles per second.
Its target was Dimorphos, a small asteroid that is a moonlet of 65803 Didymos, a slightly larger asteroid half a mile wide. With a diameter of 160 meters (530 feet), Dimorphos is about the height of the Washington Monument. Though it was chosen for this test run, the asteroid currently poses no threat to Earth. It's the unknown asteroids we have to worry about.
This strategy — sort of like a game of billiards — is believed by experts to be the best defense against space rocks.
But by hitting Dimorphos with DART, causing what's known as a "kinetic impact," scientists hoped they could shift its orbit. This strategy — sort of like a game of billiards — is believed by experts to be the best defense against space rocks. Blowing them up with nukes, like in "Armageddon," would almost certainly backfire, so it's not recommended to get astronomy advice from Michael Bay.
Like a Bay film, the DART program cost hundreds of millions of dollars ($324.5 million, to be precise) and involved at least one explosion. Only, after watching this event, you feel smarter, whereas viewing something from the "Transformers" franchise may make your brain feel like a deflated balloon.
For the first hour or so of a NASA livestream, Didymos and Dimorphos appeared as nothing more than a white blip just a few pixels wide against a sea of black. Slowly, asteroids began to fill the screen, and their features gained definition. About five minutes from impact, DART was traveling too fast and too far away for a human to be behind the controls, so it flew on autopilot. The probe precision locked onto Dimorphos and charged ahead.
ATLAS observations of the DART spacecraft impact at Didymos! pic.twitter.com/26IKwB9VSo
— ATLAS Project (@fallingstarIfA) September 27, 2022
Soon, the rocky textures of the asteroid became bigger and bigger, resembling shale gravel on a beach. Then, the feed went dark. That's when a room full of engineers at the Johns Hopkins Applied Physics Laboratory (APL) cheered and clapped at their desks. The mission was a huge success.
"We're embarking on a new era of humankind, an era in which we potentially have the capability to protect ourselves from something like a dangerous, hazardous asteroid impact," Lori Glaze, director of NASA's Planetary Science Division, said. "What an amazing thing. We've never had that capability before."
This wasn't the first time that a spacecraft had been intentionally crashed into an object in space. In 2005, the Deep Impact spacecraft (no relation to the aforementioned 1998 movie) shot 100 kilograms of copper at the comet Tempel 1 to learn more about what comets contain on the inside. And in 2014, the Rosetta space probe dropped a robotic module named Philae on the comet called 67P/Churyumov–Gerasimenko — the first controlled touchdown on a comet nucleus. Two years later, Rosetta ended its run by crashing directly into the comet.
In fact, deliberately crashing spacecraft is a relatively common practice. But DART's suicide mission is the first time that a probe has ever been used to move a space rock in a different direction.
NASA previously described the operation as "the world's first full-scale mission to test technology for defending Earth against potential asteroid or comet hazard."
The DART program, a joint operation between NASA and the APL, began late last year. They launched DART, a 600 kilogram (1,320 pound) spacecraft aboard a SpaceX rocket, eventually arriving at Dimorphos, about 6.8 million miles from Earth. NASA previously described the operation as "the world's first full-scale mission to test technology for defending Earth against potential asteroid or comet hazard."
This impact could have generated a massive crater, spewing plumes of dust into space, which could then be measured and compared to computer models, informing the design of future anti-asteroid weaponry. It will still be a while before we know exactly what happened.
To see this collision in action, astronomers pointed ground telescopes at Dimorphos, but they also used the James Webb Space Telescope and the Hubble Telescope to catch a peek of the impact. DART brought along its own webcam, the LICIACube, a tiny satellite developed by the Italian Space Agency that will give us some of the closest images of the spacecraft's suicide mission. The initial photos were courtesy of the Didymos Reconnaissance and Asteroid Camera for Optical Navigation aka the DRACO camera.
While the DART mission was historic, will it be enough to inform us of what to do should an asteroid be headed directly for Earth? Unfortunately, we actually won't know for several weeks or months. It will take time for enough data to be collected to see exactly how the orbit of Dimorphos changed.
As soon as we know more, DART's crash can be used to refine strategies for deflecting asteroids and comets to better inform future missions.
We may not even use this collision-avoidance strategy in the future. Other options on the table include ion beams and gravity tractors to push incoming objects away from us. Scientists will try anything to prevent our planet from being smushed, but the biggest factor will always be time. If we detect an incoming space rock, it could require several years to develop and send off the deflecting probe.
"The risk of impact from asteroids and other hazardous space objects is low, but the damage would be immense; developing the capability to prevent impact is a key long term objective," Rep. Don Beyer, D-Va., tweeted on Monday. It feels like Glaze is right — we may be moving into a new era for humanity, one where extinction-level events from space rocks are a little less likely.
You can watch NASA's official broadcast of DART's impact with Dimorphos below via YouTube:
