Why did a NASA spacecraft collided with an asteroid?

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CAPE CANAVERAL, Florida – In a first-of-its-kind experiment to save the world, NASA is about to hit a small, harmless asteroid millions of miles away.

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A spacecraft called Dart will be working on the asteroid on Monday, intent on hitting it head-on at a speed of 22,500 km/h. The impact should only be enough to push the asteroid into a slightly tighter orbit around its companion space rock – showing that if a deadly asteroid headed our way, we’d have a combat opportunity to divert it.

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“This is stuff from science fiction books and really cliched episodes of ‘StarTrek’ since I was a kid, and now it’s real,” NASA program scientist Tom Statler said Thursday.

Cameras and telescopes will monitor the collapse, but it will take days or even weeks to see if it has actually changed orbit.

The $325 million planetary defense test began with the launch of the DART last fall.

astronomical goal

The asteroid with a bull’s-eye is Demorphos, about 9.6 million km from Earth. He’s actually the little companion of a 2,500-foot (780-meter) asteroid called Didymos, which is a Greek word for twin. Discovered in 1996, Didymus is spinning so fast that scientists think it’s spewing out material that eventually formed a small moon. Demorphos – about 525 feet (160 meters) – orbits its parent body at a distance of less than a mile (1.2 kilometers).

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A banner hangs on a wall during the Asteroid Redirection Test (DART) Multimedia Technology Workshop, remote briefing, and tour of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, on September 12, 2022, prior to the project's test mission on September 26.  .
A banner hangs on a wall during the Asteroid Redirection Test (DART) Multimedia Technology Workshop, remote briefing, and tour of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, on September 12, 2022, prior to the project’s test mission on September 26. . Jim Watson’s photo /AFP via Getty Images

“This is really about the asteroid’s deflection, not the turbulence,” said Nancy Chabot, a planetary scientist and mission team leader at the Johns Hopkins University Applied Physics Laboratory, which is directing the effort. “This will not blow up the asteroid. It will not break it into a lot of pieces.” Instead, the impact will dig a hole tens of meters (meters) in size and dump about two million pounds (one million kilograms) of rock and dirt into space.

NASA insists there is no chance of an asteroid threatening Earth – now or in the future. That is why the pair was chosen.

Dart, the influencer

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The Johns Hopkins lab took a simple approach to developing the Dart – short the Double Asteroid Redirection Test – since it’s essentially a ram and faces certain destruction. It has one tool: a camera used to navigate, target, and chronicle the final action. Thought to be essentially a pile of rubble, Dimorphos will appear as a point of light an hour before impact, looming larger and larger in camera images beamed back to Earth. Directors are confident Dart won’t accidentally bump into the larger Didymos. The spacecraft’s navigation was designed to distinguish between the two asteroids and, in the last 50 minutes, targeted the smaller asteroid.

The size of a tiny 1,260-pound (570-kilogram) vending machine, the spacecraft will hit about 11 billion pounds (5 billion kilograms) of the asteroid. “Sometimes we describe it as running a golf cart in the Great Pyramid,” Chabot said.

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Unless Dart gets it wrong — NASA puts the odds of that at less than 10% — it will be the end of the road for Dart. If he passes screaming through both space rocks, he will face them again in two years in Take 2.

save the earth

Little Dimorphos complete a turn around the big Didymos every 11 hours 55 minutes. The Dart effect should shave about 10 minutes from that. Although the blow itself should be immediately apparent, it may take a few weeks or more to check the orbit of the young moon. Cameras on the Dart and the Tagalong micro-satellite will capture the collision up close. Telescopes on all seven continents, along with the Hubble and Webb space telescopes and NASA’s asteroid-hunting Lucy spacecraft, may see a bright flash as it hits the Dart Demorphos and sends streams of rock and dirt streaming into space. Observatories will track the pair of asteroids as they orbit the sun, to see if DART has changed the orbit of Demorphos. In 2024, a European spacecraft called Hera will track the flight of the DART to measure the results of the impact.

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Although the intended alert should only change the moon’s position slightly, that would add a significant shift over time, according to Chabot. “If you’re going to do it for planetary defense, you’re going to do it five, 10, 15, 20 years ago for this technology to work,” she said. Even if Dart got it wrong, the experiment would still provide valuable information, said Andrea Riley, NASA executive director. “That’s why we’re testing. We want to do it now and not when there’s an actual need,” she said.

astronomical missions bountiful

Planet Earth on an asteroid hunt. NASA has approximately 450 grams of debris collected from the asteroid Bennu bound for Earth. The bunker should arrive next September. Japan was the first to recover samples from the asteroid, and achieved this feat twice. China hopes to follow suit by launching a mission in 2025. Meanwhile, NASA’s Lucy spacecraft is headed to asteroids near Jupiter, after launching last year. Another spacecraft, the asteroid near Earth, is carried in NASA’s New Moon rocket awaiting liftoff; You’ll be using a solar sail to bypass a space rock less than 60 feet (18 meters) next year. In the next few years, NASA also plans to launch a telescope to conduct the census to identify hard-to-find asteroids that could pose risks. One asteroid mission is postponed while an independent review board weighs its future. NASA’s Psyche spacecraft was supposed to launch this year to a mineral-rich asteroid between Mars and Jupiter, but the team was unable to test the flight program in time.

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Eat Hollywood

Hollywood has produced dozens of killer space rock movies over the decades, including 1998’s “Armageddon” that brought Bruce Willis to Cape Canaveral to shoot, and last year’s “Don’t Look” with Leonardo DiCaprio leading an all-star cast. NASA Planetary Defense Officer Lindley Johnson believes he’s seen them all since 1979’s Meteor, his personal favorite “since Sean Connery played me.” He noted that while some sci-fi movies are more accurate than others, entertainment always wins. The good news is that the coast appears clear for the next century, with no known threats. Otherwise, “It would be like the movies, wouldn’t it?” said Thomas Zurbuchen, head of the NASA science mission. But what is worrying are unknown threats. Less than half of the 460 feet (140 m) high objects have been confirmed, with millions of smaller but still dangerous objects. “These threats are real, and what makes this time special, is that we can do something about them,” Zurbuchen said. Not by blowing up an asteroid as Willis did – that would be a last resort at the last minute – or by begging government leaders to take action as DiCaprio did in vain. If time permits, the best tactic might be to push a threatening asteroid out of our way, like a Dart.


The Associated Press’s Department of Health and Science receives support from the Howard Hughes Medical Institute’s Division of Science Education. AP is solely responsible for all content.

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