This image from NASA’s Hubble Space Telescope shows debris ejected from the surface of Dimorphos 285 hours after NASA’s DART spacecraft hit the asteroid’s surface.
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This image from NASA’s Hubble Space Telescope shows debris ejected from the surface of Dimorphos 285 hours after NASA’s DART spacecraft hit the asteroid’s surface.
NASA/ESA/STScI/Hubble
Astronomers are still monitoring this asteroid, which collided with NASA’s spacecraft in September, in a first-ever test to determine if the asteroid could have been blown up on purpose.
Almost immediately after NASA’s Double Asteroid Redirection Test (DART) mission collided with an asteroid the size of a golf cart called Dimorphos, scientists hailed it as a major success and a powerful demonstration that an asteroid’s trajectory can be altered.
“We know that this process is really efficient — more efficient than most people expected,” says Andy Cheng of the Johns Hopkins University Applied Physics Laboratory.
The experiment boosted scientists’ confidence, he said, that this deflection method could indeed work to protect the planet if Earth were threatened by dangerous space rocks.
According to a new analysis in the paper, the collision changed Dimorphos’ trajectory through space, cutting another large asteroid’s orbit time by 33 minutes. Nature. The journal this week published a study detailing the results of the unprecedented asteroid deflection experiment, along with four additional scientific reports.
NASA, ESA, STScI, and Jian-Yang Li (PSI); Video: Joseph DePasquale (STScI)
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Dimorphos is millions of miles away and roughly the size of the Great Pyramid of Giza in Egypt. Astronomers first saw it in the final moments of the mission, as the DART spacecraft zoomed in and sent back images of a gray egg-shaped asteroid strewn across the debris.
After the spacecraft touched down, it was powered down and its image stream stopped. But telescopes tracking the pair of asteroids saw the impact kick up large amounts of dust and rocky debris, lighting up the scene.
“It’s just a light cloud. A lot of dust came out. And we were just amazed. That’s when we knew we could do good science with it,” says Ariel Greikovsky, an employee of the SETI Institute. , which works with a global network of telescope enthusiasts.
Any material ejected from the asteroid by impact imparted an additional shock to the asteroid, Cheng said, much like firing a gun would recoil a weapon.
“It’s the recoil force, the extra force pushing against the asteroid,” Cheng explains, adding that the extra force was much greater than when the spacecraft crashed into the asteroid. sink into.
The orbiting Hubble Space Telescope was on the wrong side of Earth when the collision occurred, so it couldn’t observe the event, but it soon looked at the asteroid and saw the debris cloud change over time.
“It’s a really interesting thing,” said Jiang-Yang Li of the Institute of Planetary Science, adding that a comet-like tail eventually appeared and lengthened.
It looked like the tails you sometimes see on other asteroids, he said. It has never been clear what caused these so-called “active” asteroids to form, although some astronomers suspect that impacts played a role.
“DART is the first experiment to show that this effect can actually cause a tail,” he says.
Dimorphos’ flowing tail can still be seen through telescopes. “We’re still watching,” said Christina Thomas of Northern Arizona University, who said the sightings should end this month.
Next year, the European Space Agency will send a mission called Hera to take a closer look at the asteroid and determine the extent of the craters left behind. It should also be able to determine the mass of the asteroid. All of this should help astronomers better understand how asteroids move.
Although astronomers say there are currently no known large space rocks that threaten Earth, many small but still dangerous asteroids have yet to be tracked, and planetary advocates say it’s best to be prepared.
“We’ve shown that we have a way to move an asteroid,” Greikovsky says. “It makes me feel a lot better to see it work, and work very well.”
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