A NASA spacecraft that deliberately collided with an asteroid succeeded in pushing the rocky moon out of its normal course.
Today, Tuesday, the US space agency announced that the NASA spacecraft, which deliberately collided with an asteroid last month, succeeded in pushing the rocky moon from its natural course to a faster orbit, which is the first time that humanity has changed the motion of a celestial body.
The $330 million proof-of-concept mission, which took seven years to develop, represents the world’s first test of a planetary defense system designed to prevent a potential meteorite collision with Earth.
Results of telescope observations revealed at a NASA news briefing in Washington confirmed that the Sept. 26 suicide test flight of the DART spacecraft achieved its primary goal: to change the direction of the asteroid through absolute kinetic force.
NASA scientists said that astronomical measurements over the past two weeks showed that the target asteroid collided near the larger asteroid orbiting it, and that the orbital period was shortened by 32 minutes.
“This is a watershed moment for planetary defense and a watershed moment for humanity,” NASA President Bill Nelson told reporters in announcing the results. “It felt like a movie plot, but this wasn’t Hollywood.”
Last month’s impact, 6.8 million miles (10.9 million km) from Earth, was monitored in real time from the Mission Operations Center at Johns Hopkins University’s Applied Physics Laboratory (APL) in Laurel, Maryland, where the spacecraft was designed and built for NASA. .
DART’s celestial target was an egg-shaped asteroid called Dimorphos, roughly the size of a football field, that orbited about five times larger asteroid called Didymos once every 11 hours and 55 minutes.
The test flight concluded with the impactor vehicle DART, no larger than a refrigerator, as it collided directly with Dimorphos at 14,000 mph (22,531 km/h).
A comparison of pre- and post-impact measurements of the Dimorphos-Didymos pair as they eclipse one another shows that the orbital period has been shortened to 11 hours 23 minutes, with the smaller object colliding tens of meters near its mother.
Tom Statler, a DART program scientist at NASA, said the collision left Demorphos “wobbly a bit,” but that additional observations would be necessary to confirm this.
Laurie Glaese, director of NASA’s Planetary Science Division, said the result “showed that we can transform a potentially dangerous asteroid of this size” if it’s detected well enough. “The key is early detection.”
NASA scientists have said that neither of the two asteroids in question, nor DART itself, which is an acronym for the Double Asteroid Redirection Test, poses any real threat to Earth.
But Nancy Chabot, APL’s DART coordination lead, said Demorphos “is the size of an asteroid that is a priority for planetary defense.”
An asteroid the size of Dimorphos, while incapable of posing a planetary threat, could threaten a large city with a direct hit.
Scientists expected that the effect of DART would shorten the orbital path of Demorphos by at least ten minutes, but they considered that a change as small as 73 seconds would be successful. So the actual change of more than half an hour, with a margin of uncertainty plus or minus two minutes, exceeded expectations.
The relatively loose composition of the rubble that Demorphos appears to consist of may be a factor in the amount of asteroid deflection by the DART strike.
NASA said the collision released tons of rocky material from the asteroid’s surface into space, which can be seen in telescope images as a large debris plume, creating a bouncing effect that added to the force exerted on Demorphos from the impact itself.
Launched by a SpaceX rocket in November 2021, DART made most of its flight under the supervision of flight managers on the ground, with control handed over to the vehicle’s autonomous navigation system in the final hours of flight.
Demorphos and Didymus are both very small compared to the cataclysmic asteroid Chicxulub that struck Earth about 66 million years ago, wiping out about three-quarters of the world’s plant and animal species including the dinosaurs.
Smaller asteroids are more common and of more theoretical interest in the near term, making Didymos’ pair a good fit for testing for their size, according to NASA scientists and planetary defense experts.
The asteroids’ relative proximity to Earth and their double configuration also made them ideal for the DART mission.
The Dimorphos moonlet is one of the smallest astronomical objects to have received a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none of them are known to pose a potential danger to humanity, NASA estimates that many asteroids remain undiscovered in the vicinity of Earth.
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