The spacecraft that NASA deliberately crashed into an asteroid last month managed to knock the rocky moon out of its natural orbit, the first time mankind has altered the motion of a celestial body, NASA officials say.
The $330 million ($521 million) proof-of-concept mission, which was seven years in the making, also marked the world’s first test of a planetary defense system designed to avoid a potential collision of meteorites with the Earth.
Findings from the telescope’s observations presented at a NASA news conference in Washington confirmed that the suicide test flight of the DART spacecraft on September 26 achieved its primary goal: to change the direction of an asteroid through pure kinetic force.
The measurements showed that the target asteroid moved slightly closer to the larger parent asteroid orbiting in space and that its orbital period was shortened by 32 minutes.
“This is a crucial moment for planetary defense and a crucial moment for humanity,” NASA chief Bill Nelson told reporters on Tuesday. “It felt like a movie plot, but this wasn’t Hollywood.”
Last month’s impact, 10.9 million kilometers from Earth, was monitored from Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, where the spacecraft was designed and built for NASA .
The celestial target of the DART flight was an egg-shaped asteroid called Dimorphos, about the size of a football stadium, which orbited a five times larger parent asteroid called Didymos once every 11 hours and 55 minutes .
The goal was to blast the DART impactor, no bigger than a refrigerator, straight at Dimorphos at 22,531 km/h, creating enough thrust to shift the moon’s orbit closer to its larger companion.
Comparison of pre- and post-impact measurements of the Dimorphos-Didymos pair showed that the orbital period was reduced to 11 hours and 23 minutes.
Tom Statler, NASA’s DART program scientist, said the collision also left Dimorphos “wobbly a bit,” but additional observations were needed to confirm this.
The result “demonstrated that we are capable of deflecting a potentially dangerous asteroid of this size,” if detected early enough, said Lori Glaze, director of NASA’s planetary science division.
None of the asteroids involved, nor DART itself, short for Double Asteroid Redirection Test, posed any real threat to Earth, NASA scientists said.
But Nancy Chabot, head of DART coordination at the APL, said Dimorphos “is an asteroid size that is a priority for planetary defense.”
An asteroid the size of Dimorphos, while not capable of posing a threat to the entire planet, could annihilate a major city with a direct hit.
Scientists had predicted that the DART impact would shorten Dimorphos’ orbital path by at least 10 minutes, but would have considered a change as small as 73 seconds a success. So the actual change of more than half an hour exceeded expectations.
Launched by a SpaceX rocket in November 2021, DART made most of its journey under the guidance of flight directors, with control handed over to the autonomous navigation system on board the spacecraft in the final hours of the journey.
RAW 2022