The early morning liftoff started DART, NASA's first mission to test a spacecraft, which could one day save the earth from deadly space rocks.

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NASA launched a spacecraft on Wednesday with a simple mission: hitting an asteroid at a speed of 15,000 miles per hour.

The mission, the Double Asteroid Redirection Test, or DART, leaves the Earth to test whether the spacecraft can be pushed into a different orbit by hitting the asteroid. If NASA and other space agencies need to deflect asteroids to save the planet and avoid catastrophic impacts, then if the test is successful, the test results will come in handy.

The DART spacecraft lifted off from the Vandenberg Space Force base in California at 1:21 a.m. Eastern time on Wednesday (or 10:21 p.m. local time). The rocket reaches space and then returns its reusable booster to the ocean, landing on SpaceX’s unmanned ship. It takes about an hour to deploy the spacecraft in orbit, and in a few hours it will deploy solar panels to power the aircraft.

NASA broadcast the launch live on its YouTube channel at 12:30 AM on Wednesday. Or you can watch it in the video player embedded above. SpaceX also has its own live video from the launch pad.

If the night sky is not too cloudy, NASA has provided a guide so that people in Southern California can see it when the spacecraft leaves the atmosphere.

NASA is crashing DART into an asteroid. This is the first test of a planetary defense method that could one day save a city or an entire planet from a catastrophic asteroid impact.

NASA Administrator Bill Nelson said in an interview that DART is “a bit like a reenactment of Bruce Willis’ film "The End of the World," even though it’s completely fictional."

If all of DART goes according to plan, NASA will have a confirmed weapon in its planetary defense arsenal. If another asteroid eventually collides with the Earth, the world's space agency will be confident that an asteroid missile like DART will knock the space rock off.

After launching into space, the spacecraft will orbit the sun for nearly a complete orbit, and then intersect with Dimorphos, which is an asteroid the size of a football field. Every 11 hours and 55 minutes, it is closely connected to a larger asteroid Didymos. . Astronomers call these two asteroids a binary star system, one of which is the other small satellite. Together, these two asteroids orbit the sun every two years.

Dimorphos poses no threat to the earth, and the mission is essentially a goal exercise. The DART impact will occur in late September or early October next year, when the double asteroid is the closest point to the Earth, about 6.8 million miles.

Four hours before the impact, the DART spacecraft, officially known as the Power Impactor, will automatically guide itself directly towards Dimorphos and make a frontal collision at a speed of 15,000 miles per hour. The onboard camera will capture photos in real time and send them back to Earth until 20 seconds before the impact. A microsatellite of the Italian Space Agency, deployed 10 days before the impact, will take images of DART before and after the impact every 6 seconds at a distance of 34 miles from the asteroid.

Telescopes on Earth will fix their lenses at the crash site, showing two asteroids as small dots reflecting sunlight. To measure whether the DART impact changed Dimorphos' orbit around Didymos, astronomers will track the time between one flash of light (indicating that Dimorphos has passed in front of Didymos) and another flash, which indicates that Dimorphos is orbiting Didymos.

If Dimorphos orbits Didymos for at least 73 seconds, DART will successfully perform its mission. But mission managers expect that the impact will further extend the asteroid's orbit, about 10 to 20 minutes.

Simply hitting dangerous space rocks with nuclear weapons, as in "End of the World" and other science fiction disaster movies, can create a more dangerous space rock field, increasing the danger to the earth, rather than eliminating them.

Nevertheless, if used properly, nuclear devices are still one of the few conceptual tools in NASA's planetary defense toolbox.

Brent Barbie, an aerospace engineer at NASA’s Goddard Space Flight Center, said that for any asteroid and distant asteroid that may threaten the Earth in the next few decades, a mission like DART is “very likely to complete the mission. ".

"But if the asteroid is larger than this, or if the warning time is shorter than this, then this is where you transition from observing a kinetic impactor to a nuclear device," Mr. Barbie said.

Astronomers and officials from various space agencies have simulated using the force of a nuclear explosion to deflect asteroids away from the Earth.

Other simulations of destroying asteroids have shown that nuclear explosives can be used to destroy smaller asteroids that are nearly two months away from the impact, and pose a small risk to the Earth.

"In addition to the physical characteristics of the device itself and how the device interacts with the asteroid, there are many challenging aspects to nuclear missions," Mr. Barbie said.

The treaty prohibiting the use of nuclear weapons and the "Outer Space Treaty", the cornerstone of international space law signed in the 1960s, prohibits the placement or use of nuclear weapons in space

This shows that any country's emergency use of a spacecraft equipped with a nuclear warhead to defend against a deadly asteroid would constitute a violation of the treaty. But this legal dilemma can be resolved through an emergency meeting of the UN Security Council.

Headlines about asteroids passing close to our planet are commonplace. But according to NASA, the Earth should not be affected by dangerous space rocks in the next century.

The agency maintains a database of near-Earth objects within a range of approximately 28 million miles from Earth. In the next few days, the closest celestial body to Earth will be an asteroid between 50 and 100 feet in diameter, which will reach within 511,246 miles on Thanksgiving Day. (This is about twice the distance to the moon.)

So far, NASA has tracked approximately 27,000 such objects, which accounts for only 40% of the agency's total missions searched for under its Near-Earth Object Observation Program.

NASA also maintains the Sentinel Risk Table, which is a separate list of asteroids that have a higher probability of impacting the Earth (although the probability is still extremely low). One celebrity on the list is Bennu, a gravel acorn-shaped asteroid about the size of a skyscraper. It has a 0.057% chance of hitting the earth sometime between 2178 and 2290.

NASA sent a spacecraft named OSIRIS-REx to Bennu last year to scoop up a suitcase worth of rock samples and bring them back to Earth in September 2023.

Of course, whether it’s crashing into a Canadian woman’s bed or smashing a window when the Russian city’s atmosphere returns to the atmosphere, space rocks always surprise people large and small on the planet.

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