On Wednesday, NASA launched a spacecraft with a simple mission: to crash into an asteroid at 15,000 miles per hour.
The mission, the Double Asteroid Redirection Test, or DART, left Earth to test whether slamming a spaceship into an asteroid can push it into a different trajectory. The test results, if successful, will come in handy if NASA and other space agencies ever need to deflect an asteroid to save Earth and avoid catastrophic impact.
When did the launch take place and what happens next?
The DART spacecraft lifted off from the top of a SpaceX Falcon 9 rocket on Wednesday at 1:21 a.m. Eastern time (or 10:21 p.m. local time) from Vandenberg Space Force Base in California. The rocket reached space before sending its reusable booster back to the ocean to land on a SpaceX drone. It will take about an hour to deploy the spacecraft into orbit, and a few hours later it will deploy solar panels to power the vehicle as it travels.
NASA is hosting a live broadcast of the launch on its YouTube channel which began at 12:30 a.m. on Wednesday. Or you can watch it in the built-in video player above. SpaceX also has its own live video feed from the launch pad.
If the night sky isn’t too cloudy, NASA has provided a guide showing where residents of Southern California might see the spacecraft as it exits the atmosphere.
Why is NASA crashing into an asteroid?
NASA crushes DART on an asteroid to test, for the first time, a planetary defense method that could one day save a city, or perhaps the entire planet, from a catastrophic asteroid impact.
DART “is in a way a rerun of the Bruce Willis film ‘Armageddon’, although it’s totally fictional,” NASA administrator Bill Nelson said in an interview.
If all goes according to plan with DART, NASA will have a confirmed weapon in its planetary defense arsenal. If a different asteroid were to end up on a collision course with Earth, global space agencies would have confidence that an asteroid missile like DART would chase space rock.
How will the mission work?
After launching into space, the spacecraft will complete nearly a full orbit around the sun before passing Dimorphos, a football-sized asteroid that orbit closely with a larger asteroid, called Didymos, all of which. the 11 hours and 55 minutes. Astronomers call these two asteroids a binary system, where one is a mini-moon for the other. Together, the two asteroids complete a full orbit around the sun every two years.
Dimorphos poses no threat to Earth, and the mission is essentially target training. The impact of DART will occur in late September or early October next year, when the binary asteroids are at their closest point to Earth, approximately 6.8 million kilometers away.
Four hours before impact, the DART spacecraft, officially referred to as the Kinetic Impactor, will autonomously proceed directly to Dimorphos for a head-on collision at 15,000 miles per hour. An on-board camera will capture and return photos to Earth in real time up to 20 seconds before impact. A tiny Italian Space Agency satellite, deployed 10 days before impact, will approach 34 miles from the asteroid to take images every six seconds in the moments before and after DART impact.
How will NASA know if DART is successful?
Telescopes on Earth will fix their lenses at the crash site, showing the two asteroids as tiny dots of reflected sunlight. To measure whether the impact of DART altered Dimorphos’ orbit around Didymos, astronomers will track the time between a flicker of light – which indicates that Dimorphos has passed in front of Didymos – and another, which indicates that Dimorphos has orbited behind. Didymos.
If Dimorphos’ orbit around Didymos is extended by at least 73 seconds, DART will have successfully completed its mission. But mission leaders expect the impact to lengthen the asteroid’s orbit even further, by about 10 and 20 minutes.
Why can’t Earth just detonate asteroids that threaten the planet?
The simple act of hitting dangerous space rocks with a nuclear weapon, as in “Armageddon” and other catastrophic science fiction films, could create a field of more dangerous space rocks, multiplying the dangers posed to Earth, rather than to eliminate them.
Yet a nuclear device, if used correctly, is one of the few conceptual tools in NASA’s planetary defense toolkit.
For all of the distant small asteroids that could threaten Earth over the next several decades, a mission like DART “has a pretty good chance of getting the job done,” said Brent Barbee, an aerospace engineer at NASA’s Goddard Space Flight Center.
“But if the asteroid is bigger than that, or the warning time is shorter than that, then this is where you go from looking at kinetic impactors to nuclear devices,” Mr. Barbee said. .
Astronomers and officials from various space agencies have simulated the deflection of an asteroid away from Earth with the force of nuclear explosions.
Further asteroid destruction simulations have shown that nuclear explosives could be used to annihilate smaller asteroids within two months of impact, while posing little risk to Earth.
“There are a lot of difficult aspects of a nuclear mission besides the physics of the device itself and how the device would interact with the asteroid,” said Mr. Barbee.
Treaties banning the use of nuclear weapons and the Outer Space Treaty, the cornerstone of international space laws signed in the 1960s, prohibit the placement or use of nuclear weapons in outer space.
This suggests that a country’s emergency use of a nuclear-powered spacecraft to repel a killer asteroid would amount to a violation of the treaty. But this legal situation could be resolved by an emergency meeting of the United Nations Security Council.
Are asteroids heading our way right now?
Headlines about asteroids passing close to our planet are commonplace. But Earth should be safe from dangerous space rocks for the next century, according to NASA.
The agency maintains a database of near-Earth objects that are located approximately 28 million kilometers from Earth. The closest object to Earth over the next few days will be an asteroid between 50 and 100 feet wide, located 511,246 miles away on Thanksgiving Day. (It’s about twice the distance from the moon.)
So far, around 27,000 of these objects have been tracked by NASA, which is only 40% of the total amount the agency is tasked with finding as part of its near-Earth object observation program.
NASA also maintains the Sentry Risk Table, which is a separate list of asteroids that are more likely to impact Earth (although the odds are still extremely low). A celebrity on this list is Bennu, a gritty acorn-shaped asteroid the size of a skyscraper. It has a 0.057% chance of impacting Earth between 2178 and 2290.
NASA sent a spacecraft called OSIRIS-REx to Bennu last year to collect the equivalent of a suitcase of rock samples and bring them back to Earth in September 2023.