Why will a NASA spacecraft crash into an asteroid

CAPE CANAVERAL, Fla. (AP) – In a first-of-its-kind, world-saving experiment, NASA is about to rescue a small, harmless asteroid millions of miles away.

A spacecraft named Dart will approach the asteroid on Monday, intending to slam it head-on at 14,000 mph (22,500 kph). The impact should be direct enough to push the asteroid into a slightly tighter orbit around its companion space rock – indicating that if a killer asteroid keeps heading forward, we’d have a fighting chance of redirecting it.

Cameras and telescopes will watch the crash, but it will take months to determine if the orbit has actually changed.

The $325 million planetary defense test began with Dart’s launch last fall.


The bull’s-eye asteroid is Dimorphos, about 7 million miles (9.6 million kilometers) from Earth. It’s actually the side of a 2,500-foot (780-meter) asteroid named Didymos, Greek for twin. Discovered in 1996, Didymos is spinning so fast that scientists believe it shed material that eventually formed a moon. Dimorphos – about 525 feet (160 meters) across – orbits its parent body by less than a mile (1.2 kilometers).

“This is really an asteroid deflection, not an intrusion,” said Nancy Chabot, a planetary scientist and mission team leader at Johns Hopkins University, who is managing the effort. “This won’t blow up the asteroid. He’s not going to put it in a lot of pieces.” Instead, the impact will leave a crater thousands of yards (meters) in size and send about 2 million pounds (1 million kilograms) of rocks and dirt into space.

NASA insists that there is no chance that an asteroid will pose a threat to Earth – now or in the future. That’s why the pair was chosen.


Johns Hopkins took a minimalist approach in developing Dart – short for Double Asteroid Redirect Test – since it is essentially a battering ram and is destined for certain destruction. He has one tool: a camera that is used to navigate, focus and convey the final action. Believed to be essentially a pile of rubble, Dimorphos will emerge as a point of light hours before impact, swinging more and more in the camera images sent back to Earth. Managers are confident that Dart won’t make it into the Didymos by mistake. The spacecraft’s navigation is designed to distinguish between the two asteroids and, in the final 50 minutes, focus on the smaller one.

The size of a small vending machine at 1,260 pounds (570 kilograms), the spacecraft will slam into about 11 billion pounds (5 billion kilograms) of an asteroid. “Sometimes we describe it as putting a golf cart into a Great Pyramid,” Chabot said.

Unless Dart misses – NASA puts the chance of that happening at less than 10% – that’s the end of the road for Dart. If he goes screeching past the two space rocks, he’ll meet them again in a few years for Take 2.


Little Dimorphos makes a lap around Didymos big every 11 hours and 55 minutes. Dart’s impact should be about 10 minutes from there. While the strike itself should be visible immediately, it will take months for the moonlet’s tweaked orbit to become a reality. Cameras on Dart and a mini-tagging satellite will capture the collision shortly. Telescopes on all seven continents, as well as the Hubble and Webb space telescopes and NASA’s asteroid-hunting Lucy spacecraft, may see a bright flash when Dart hits Dimorphos and sends streams of rock and dirt into the space. The observatories will track the pair of asteroids as they orbit the sun, to see if Dart has changed Dimorphos’ orbit. In 2024, a European spacecraft named Hera will retrace Dart’s journey to measure the results of the impact.

While the proposed nudge should only slightly change the moon’s position, it will add up to a big change over time, according to Chabot. “So if you were going to do this for planetary defense, you would do it five, 10, 15, 20 years in advance for this technique to work,” she said. Even if Dart loses, the experiment will still provide value. insight, said NASA program executive Andrea Riley. “This is why we tested. We want to do it now rather than when there is a real need,” she said.


Planet Earth is in search of an asteroid. NASA has close to a pound (450 grams) of debris collected from the asteroid Bennu towards Earth. The stash should arrive next September. Japan was the first to recover asteroid samples, making the feat a double feat. China hopes to follow suit with a mission to be launched in 2025. Meanwhile, NASA’s Lucy spacecraft is heading to asteroids near Jupiter, having been launched last year. Another spacecraft, Near-Earth Asteroid Gasout, is loaded into NASA’s new moon rocket awaiting liftoff; will use a solar sail to fly past a space rock less than 60 feet (18 meters) next year. In 2026, NASA will launch a census taker telescope to find difficult-to-find asteroids that could pose risks. One asteroid mission has been established and an independent review board weighs its future. NASA’s Psyche spacecraft should have launched this year to a metal-rich asteroid between Mars and Jupiter, but the crew was unable to test the flight software in time.


Hollywood has churned out many space rock killer movies over the years, including 1998’s “Armageddon” which brought Bruce Willis to Cape Canaveral for filming, and last year’s “Don’t Look Up” starring Leonardo DiCaprio All-in-one program. a star was cast. NASA planetary protection officer Lindley Johnson reveals he’s seen them all since 1979’s “Meteor,” his personal favorite “since Sean Connery played me.” While some sci-fi movies are more accurate than others, he noted, entertainment always wins. The good news is that the coast seems clear for the next century, with no known threats. Otherwise, “it would be like the movies, right?” said Thomas Zurbuchen, NASA’s science mission chief. However, the unknown threats are a matter of concern. Less than half of the 460-foot (140-meter) objects have been confirmed, with millions of smaller but still dangerous objects zooming around. “These threats are real, and what makes this time special is that we can do something about it,” Zurbuchen said. Not by blowing up an asteroid like Willis’ character did – that would have been a last minute option – or by begging government leaders to take action like DiCaprio’s character did in vain. If time permits, the best tactic may be to push the threatening asteroid out of our way, like Dart.


The Associated Press Department of Health and Science is supported by the Department of Science Education of the Howard Hughes Medical Institute. The AP is solely responsible for all matters.

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