Asteroid trajectory altered by NASA’s planetary defense system

A NASA spacecraft that intentionally crashed into an asteroid last month managed to propel the rocky moon from its natural trajectory into a faster orbit, in what was the first time mankind had altered the motion of a celestial body, the authorities said US space agency announced on Tuesday.

The $330 million proof-of-concept mission, which was seven years in development, also represented the world’s first test of a planetary defense system designed to prevent a potential doomsday meteorite collision with Earth.

Results of telescopic observations, revealed at a NASA news conference in Washington, confirmed that the September 26 suicide test flight of the DART spacecraft had achieved its primary objective: Changing the direction of an asteroid through sheer kinetic force.

Astronomical measurements over the past two weeks have shown that the target asteroid has been bumped slightly closer to the larger parent asteroid it orbits and that its orbital period has been shortened by 32 minutes, NASA scientists said.

“This is a turning point for the defense of the planet and a turning point for humanity,” NASA chief Bill Nelson told reporters upon announcing the results. “It felt like a movie plot, but this wasn’t Hollywood.”

Last month’s impact, 10.9 million kilometers from Earth, was monitored in real time by 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 became.

DART’s celestial target was an egg-shaped asteroid called Dimorphosabout the size of a soccer stadium, orbiting a parent asteroid about five times its size, called Didymos, every 11 hours and 55 minutes.

The test flight ended with the DART impactor vehicle, no larger than a refrigerator, slamming directly into Dimorphos at approximately 14,000 mph.

Comparing measurements of the Dimorphos-Didymos pair before and after impact, with one dwarfing the other, shows that the orbital period was shortened to 11 hours and 23 minutes, with the smaller object crashing 10 meters closer to its parent .

wobbling possible

Tom Statler, NASA’s DART program scientist, said the collision also “wobbled” Dimorphos “a little bit,” but additional observations are needed to confirm this.

The result “demonstrated that we are capable of deflecting a potentially dangerous asteroid of this size” if spotted in time, said Lori Glaze, director of NASA’s Planetary Sciences Division. “The key is early detection.”

Neither the two asteroids involved nor DART itself, short for Double Asteroid Redirection Test, posed an actual threat to Earth, NASA scientists said.

But Nancy Chabot, coordination manager of DART at APL, said that Dimorphos “is a size of asteroid that is a priority for defending the planet.”

While an asteroid the size of a Dimorphus cannot pose a planetwide threat, it could level a major city with a direct hit.

Scientists had predicted that the DART impact would shorten Dimorphos’ orbit by at least 10 minutes, but considered a change of just 73 seconds a success. So the actual change of more than half an hour, with a margin of uncertainty of plus or minus two minutes, exceeded expectations.

The relatively loose debris composition that makes up Dimorphos could be a factor in how much the asteroid was moved by DART’s strike.

The impact ejected tons of rocky material from the asteroid’s surface into space, visible in telescopic images as a large cloud of debris, creating a recoil effect that contributed to the force exerted on Dimorphos by the collision itself, NASA said. Launched from a SpaceX rocket in November 2021, DART completed most of its journey under the direction of flight controllers on the ground, with control handing over to the vehicle’s autonomous onboard navigation system in the final hours of the journey.

Dimorphos and Didymos are both tiny compared to the cataclysmic asteroid Chicxulub, which struck Earth about 66 million years ago and wiped out about three quarters of the world’s plant and animal species, including dinosaurs.

Smaller asteroids are much more common and pose a bigger theoretical problem in the short term, making the Didymos pair suitable test objects for their size, according to NASA scientists and planetary defense experts.

The relative proximity of the two asteroids to Earth and their dual configuration also made them ideal for the DART mission.

One of the smallest astronomical objects to have a permanent name, the Dimorphos moon is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable threat to humanity, NASA estimates that many more near-Earth asteroids remain undetected.

Source:
Reuters