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联系方式 NASA slammed into an asteroid. Hubble just spotted a spectacular effect.
NASA's unprecedented asteroid experiment is still churning out results.
Last year in a mission called DART, the space agency intentionally slammed a sacrificial spacecraft into an asteroid called Dimorphos, which was 7 million miles from Earth. Scientists hoped to prove civilization could alter the path of a menacing asteroid— should one be on a collision course with our planet — and they successfully nudged the (non-threatening) 525-foot-wide space rock.
Now, planetary researchers are watching the aftermath of the event to gather all the information possible about how to best change the trajectory of, or deflect, a future incoming asteroid. NASA released an image captured by the legendary Hubble Space Telescope — orbiting some 332 miles above Earth — showing a "swarm of boulders" from the experimental impact, which you can see below.
"This is a spectacular observation – much better than I expected," David Jewitt, a planetary scientist at The University of California, Los Angeles, said in a statement. "We see a cloud of boulders carrying mass and energy away from the impact target. The numbers, sizes, and shapes of the boulders are consistent with them having been knocked off the surface of Dimorphos by the impact."
"The boulders are some of the faintest things ever imaged inside our solar system," Jewitt added.
SEE ALSO:How likely is a terrible asteroid impact in your lifetime?Hubble glimpsed these space boulders, ranging in size from three to 22 feet wide, from millions of miles away.
The circled blue dots around Dimorphos show the locations of the boulders.Credit: NASA / ESA / David Jewitt (UCLA) / Alyssa Pagan (STScI)The 14,000 mph DART impact was like slamming a spacecraft the size of a vending machine into a space rock the size of a stadium.
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Slamming a spacecraft into Dimorphos may sound dramatic — but the goal was just to give it a nudge. During a true deflection of an incoming asteroid, such a nudge would happen many years or decades in advance of the imminent collision. "That's enough time to make sure it misses Earth," Andrew Rivkin, a planetary astronomer at the Johns Hopkins University Applied Physics Laboratory and one of DART's lead scientists, told Mashable last year. Over years, a tiny alteration in an asteroid's movement adds up to a big change in the ultimate trajectory.
This strategy, of course, requires knowing what's coming. In good news, astronomers have already detected over 27,000 near-Earth objects, and have discovered some 1,500each year since 2015.
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Astronomers estimate that thousands of sizable asteroids over 460 feet wide remain unfound. Fortunately, astronomers have already located over 90 percent(and counting) of the rocks half-a-mile wide or bigger — the kind that could spell catastrophe for large swathes of Earth. But the smaller, more elusive rocks still have a strong potential to sneak up on us. A rock some 187 to 427 feet across swooped by Earth in 2019 and surprised scientists.
In the coming years, we'll get a close view of DART's impact scene. The European Space Agency's Hera mission will visit Dimorphos in 2026. One day, this first asteroid deflection experiment may play a role in saving countless lives from an incoming space rock.