![]() In particular, scientists are eager to study the huge cloud of dust and debris thrown out by the impact, which stretches at least 6,000 miles (10,000 km) long and has persisted for weeks. But despite the fact that the DART spacecraft has been smashed to smithereens, researchers’ work is far from complete. The mission can now be crowned a success. “As new data come in each day, astronomers will be able to better assess whether, and how, a mission like DART could be used in the future to help protect Earth from a collision with an asteroid if we ever discover one headed our way,” said NASA planetary science division director Lori Glaze in a press release. It’s a watershed moment in the field of planetary defense, which aims to understand and ideally mitigate the risks posed to Earth from asteroids and comets that may cross our planet’s path. That’s roughly 26 times the mission’s 73-second baseline for success. After following the pair for two weeks, NASA announced yesterday that Dimorphos’ 11-hour and 55-minute orbit has since shrunk to 11 hours and 23 minutes, a difference of 32 minutes. DART’s goal was to adjust the orbit of Dimorphos around Didymos, aiming to alter its nearly 12-hour period by at least 73 seconds. The target, Dimorphos, is the 525-foot-wide (160 meters) moonlet orbiting a larger asteroid, 65803 Didymos, which is 0.5 mile (780 m) across. The hit was intentional, the culmination of NASA’s Double Asteroid Redirection Test (DART) designed to determine whether a “kinetic impact” - i.e., hitting an asteroid with a spacecraft - could change its trajectory. According to CNEOS’ census, there are 855 such asteroids measuring at least 1 km (0.62 mi.), and more than 10,000 that are at least 140 m (460 ft.) across.In late September, a 1,260-pound (570 kilograms) spacecraft traveling 14,000 mph (22,530 km/h) smacked directly into a small asteroid named Dimorphos, throwing up a massive cloud of dusty debris. That’s considered close enough that even a slight change in their trajectory could put us in their path. The space agency’s Center for Near Earth Object Studies (CNEOS) keeps a running tally of asteroids that fly within 45 million km (28 million mi.) of Earth. The good news is, NASA is doing a pretty good job of finding those rocks and tracking their trajectory. ![]() Much more troubling is the huge population of wild rocks out there-asteroids that fly free through the solar system and could one day come our way. So as a target for celestial skeet-shooting it served its purpose well. “The key point of this type of technique is to just give that little nudge such that the asteroid crosses over Earth’s path, either just before we get there or just after we’ve gone by,” said Nancy Chabot, DART science coordinator at the Johns Hopkins Applied Physics Laboratory in Laurel, Md.īut Dimorphos is both a harmless and relatively static object-a known rock that keeps its distance at a known spot in space, never venturing anywhere near Earth. The DART impact was intended as a test of the kind of deflection technology that might one day be necessary to save Earth from just such a killer rock. Neither Dimorphos nor Didymos pose any danger to Earth, but other asteroids out there do pose a potential collision risk to our planet. The purpose of the cosmic collision? To see if DART’s impact could nudge Dimorphos, speeding it up slightly and shortening its orbit around Didymos. Dimorphos is a moonlet of the larger, 780 m (2,560 ft) asteroid Didymos, making one revolution around its parent rock every 11 hours and 55 minutes. The spacecraft, known as DART (for Double Asteroid Redirection Test), was launched last November, and its sole job was to fly out to the small, 160 m (525 ft.) asteroid Dimorphos, and crash into it at at 22,500 k/h (14,000 mph). And we should all be very glad they did, because today the Earth feels a little bit safer than it did yesterday. The mission managers at NASA spent $330 million to send a refrigerator-sized spacecraft 7 million miles (11 million km) into space and punch an asteroid in the nose.
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