The dinosaurs never stood a chance. But starting next week maybe we will.
A NASA spacecraft traveling at 4 miles per second will impact an asteroid just after 7 p.m. Eastern Time on Monday, September 26. The pre-planned intercept will be the first human attempt to throw a space object off course and demonstrate the ability to deflect an asteroid hurtling toward Earth.
That Double Asteroid Redirection Test or the DART mission, managed by the Johns Hopkins Applied Physics Laboratory or APL for NASA, will test planetary defenses. A NASA press release calls the interception “kinetic impact deflection,” but think of it this way: you’re going to shoot down an asteroid the size of the Washington Monument with a bullet the size of a vending machine.
dr Terik Daly, a planetary scientist on the DART mission team at Johns Hopkins APL, spoke Coffee or Die Magazine about the purpose of the mission.
The SpaceX Falcon 9 rocket carrying the Double Asteroid Redirection Test or DART spacecraft on board is seen at sunrise, Tuesday, November 23, 2021, at Space Launch Complex 4E at Vandenberg Space Force Base, California. NASA photo by Bill Ingalls.
NASA/Bill Ingalls/(NASA/Bill Ingalls)
“For example, if one day we were in a situation where we were planning how to respond to an asteroid that we thought posed a threat to Earth, we want to know, ‘How much push do we have to give it give asteroid to get it out of the way?’” Daly said.
A SpaceX rocket launched the DART spacecraft from Vandenberg Space Force Base in California on November 23, 2021.
The DART spaceball will impact an asteroid called Dimorphos, a 535-foot-wide asteroid orbiting Didymos, a larger asteroid orbiting the Sun.
Scientists chose Dimorphos as their target, Daly said, because of its intertwined orbit with Didymos, which scientists call a binary asteroid system.
It’s safer that way.
Infographic showing the effects of the Double Asteroid Redirection Test aircraft on the orbit of Dimorphos from the NASA/Johns Hopkins Applied Physics Laboratory.
Infographic showing the effect of the DART plane’s impact on Dimorphos’ orbit, from NASA/Johns Hopkins Applied Physics Laboratory.
“We’re targeting this binary asteroid system with this test so we don’t inadvertently send an asteroid toward Earth,” Daly said.
Since Dimorphos is orbiting another asteroid, accelerating Dimorphos will change its orbit around Didymos, but not Didymos’ orbit around the Sun.
“When you drive a car, you hope you never have a car accident, but you want to know your airbags are working, right?” said Daly. “We want to do this test, but we want to test this technology in a way that doesn’t pose a threat to Earth.”
Scientists estimate that an asteroid about 10 kilometers wide – about 60 times larger than Dimorphos – struck Earth 66 million years ago, wiping out up to 75% of species on Earth, including dinosaurs.
NASA is tracking a variety of asteroids around Earth, some of which could be dangerous, Daly said, although none pose an immediate threat.
A compilation of 243 images acquired on July 27, 2022 by the Didymos Reconnaissance and Asteroid Camera for Optical Navigation that discovered Didymos. Assembled by the Jet Propulsion Laboratory Double Asteroid Redirection Test Navigation Team.
Assembled by the Jet Propulsion Laboratory Double Asteroid Redirection Test Navigation Team.
“The really big asteroids – think like dinosaur killers – we know where they all are, we don’t worry about that, do we? We don’t care about Toyota Corolla-sized asteroids — lots of them — because they burn up in the atmosphere, right?” Daly said.
Asteroids more than 460 feet wide, like Dimorphos, could wipe out metropolitan areas if they hit Earth, Daly said. All in all, NASA astronomers It is estimated that there are 25,000 near-Earth asteroids close to this size.
“We don’t know that asteroids will be coming our way for at least the next 100 years,” Daly said. But astronomers are only aware of about 40% of asteroids big enough to wreak regional havoc, he said.
“That is a cause for concern. If we don’t know what’s out there, we can’t prepare very well for it,” Daly said. “Congress actually passed a law that says NASA must find 90% of all near-Earth asteroids within 140 meters [or 500 feet] and bigger. That hasn’t happened yet. NASA is working on it.”
The University of Arizona and the Jet Propulsion Laboratory at the California Institute of Technology are working towards this goal. Scientists will next launch a telescope called the surveyor of near-earth objectssaid Daly, who has “one job and one job only, which is to look for asteroids that might come close to Earth.”
Engineers from the Double Asteroid Redirection Test Team lift and inspect the Light Italian CubeSat for asteroid imaging after it arrived at the Johns Hopkins Applied Physics Laboratory in August 2021. Johns Hopkins Applied Physics Laboratory, photo by Ed Whitman.
DART’s final path to impact will begin when the ship is approximately 56,000 miles from its target. For the next four hours, DART will autonomously target Dimorphos using its onboard guidance system known as Small-Body Maneuvering Autonomous Real Time Navigation, or SMART Nav.
“When this spacecraft is flying at 4 miles per second and has to hit something the size of a giant Ferris wheel, we can’t happily stab it from the ground,” Daly said. “So the plane pilots itself to hit the asteroid.”
Scientists timed the test to capture Dimorphos at its closest pass to earth, about 6.7 million miles away.
This will allow the DART mission team to use telescopes to observe the impact and its aftermath. Right now, Dimorphos orbits Didymos about every 12 hours, Daly said. The DART spacecraft is expected to shift this orbital period by a few minutes.
The reconnaissance and asteroid camera Didymos for optical navigation, resp Dracoa high-performance camera onboard DART, will take onboard photos up until impact that will destroy the spacecraft.
Meanwhile, the Light Italian CubeSat for Imaging of Asteroids, or LICIACube, a small satellite that hitchhiked with the DART spacecraft until it broke up on September 12, will photograph the crash up close.
“Success means #1, we hit the asteroid,” Daly said. “When you think about shooting something with a gun, it throws up a bunch of debris, right? And when there’s a lot of that debris, it acts a bit like a rocket engine and actually gives the asteroid more thrust than just the spacecraft would.”
Direct impact is one of three methods that Daly says could throw an asteroid off course.
“Another is called a gravitational attractor, which if you think about taking a spacecraft, putting it next to an asteroid for a while, and a little gravitational pull of that spacecraft over a period of decades can change the orbit of the asteroid,” Daly said . “And the other options include nuclear devices, and from what I’ve heard, those have not been tested.”
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