Illustration of DART approaching Dimorphos.
NASA/Johns Hopkins APL
NASA crashed a spacecraft into an asteroid, in a first-of-its-kind experiment in planetary defense.
The space agency wants to see whether it’s a viable method for deflecting rocks that could threaten Earth.
Here is how this experiment works and why it is important, in 13 facts, photos, and graphs.
NASA made history on Monday when it purposefully crashed a spacecraft into an asteroid about 6.8 million miles away as part of its Double Asteroid Redirection Test (DART) mission.
Scientists hope the mission will give us information about whether we can use spacecraft to deflect asteroids that would otherwise impact Earth.
Though there is no immediate danger, experts say that we would be poorly prepared if a large asteroid were heading toward Earth today.
Here is how this experiment works, in 13 facts, photos, and graphs.
NASA/Johns Hopkins APL
The gif above shows real footage taken by a camera onboard the spacecraft, which recorded its last moments before impact.
NASA Live
The pictures show the spacecraft flying past an asteroid called Didymos, then heading straight towards Dimorphos, a smaller asteroid in Didymos’ orbit, where it ultimately crashed.
The live feed stopped abruptly at the moment of impact when it cut to a red screen.
Scientists are now waiting for the footage from a small satellite that was traveling alongside the spacecraft. It will beam high-resolution photos of the impact back within the next few weeks.
The moment the spacecraft crashed into the asteroid was captured by the Asteroid Terrestrial-impact Last Alert System (ATLAS) project, a NASA-funded project from the University of Hawaii that uses four telescopes that automatically scan the sky for asteroids at night.
The video, which shows debris flying off of the asteroid after impact, can be seen here.
NASA will be monitoring the debris pattern from Earth in an attempt to better understand the effects of the impact should it happen closer to Earth.
Reuters/NASA/JPL-Caltech/Handout
The DART mission tested just one of three potential ways NASA has conceived to deflect asteroids heading towards Earth.
The first is to detonate an explosive device near the asteroid so that it breaks up into smaller, less dangerous chunks, Insider previously reported.
The second is to use a powerful laser with hopes that it would heat up the rock enough so that it would change its orbit, per Insider’s previous reporting.
The third strategy is what DART tested: bump a spacecraft into the asteroid with enough force to knock it off of its trajectory and cause it to miss the Earth.
Peter Carril/ESA
Since 2013, NASA has been running simulations in which an international panel of experts is tasked with saving the Earth from an asteroid.
The simulations are designed to be particularly tricky and often simulate very little time before impact.
But out of seven simulations, the experts were only completely successful once.
Experts previously told Insider that, at our current state of readiness, we’d likely need five to 10 years to build and launch a customized mission to stop an asteroid.
AP
There have been two recent instances in which dangerously sized asteroids came close to the Earth, and weren’t spotted until it was too late, Insider’s Morgan McFall-Johnsen reported.
In 2013, an asteroid the size of a house came close enough to shatter windows and collapse buildings in Chelyabinsk, Russia. It injured more than 1,000 people.
In 2019, a 427-foot-wide asteroid, which is big enough to wipe out a city, passed within 45,000 miles of Earth. Experts only spotted it days earlier.
Experts only have the resources, capacity, and technology to be able to track about 40% of city-killing asteroids that fly by the Earth.
ESA-Science Office
Dimorphos is about 535 feet wide.
That makes it big enough to be a “city killer.” If it were to hit the Earth, it could wipe out New York, Insider’s Morgan McFall-Johnsen previously reported.
NASA JPL DART Navigation Team
At about 6.8 million miles away, Dimorphos was chosen in part because it is far enough away that it doesn’t pose any risk to our planet.
The spacecraft, which was launched on November 24, took 316 days to reach the asteroid.
NASA/Johns Hopkins APL
The other reason Dimorphos was chosen is that is orbits a larger asteroid, which makes it easier for NASA to measure the effect of the impact.
If NASA’s calculations are correct, Dimorphos’ orbit around Didymos should be several minutes shorter.
NASA/Johns Hopkins APL
Dimorphos has a mass of about 11 billion pounds, while the DART spacecraft weighed around 1,376 pounds.
On the graph above, the spacecraft is only slightly bigger than the bus on the far left side of the scale.
NASA/Johns Hopkins APL/Ed Whitman
Without its solar wings deployed, the spacecraft easily fit on a truck for transport.
In spite of its small size, the impact of the craft could deflect the asteroid’s orbit by a fraction of a percent. If calculations are correct, that is enough to significantly change its trajectory.
NASA will keep monitoring the asteroids’ tracks in the coming weeks to see if the test was successful.
NASA/Joel Kowsky
DART has so far been relatively cheap at about $313 million so far, according to Space.com.
By comparison, NASA’s Artemis mission to bring humans back to the moon — for which a new moon megarocket is due to be launched in coming weeks to months — will cost about $93 billion, per Space.com
NASA/JPL-Caltech
NASA will be closely monitoring the effects of the DART mission to determine whether this strategy is viable for planetary defense.
In the meantime, space agencies are also turning working hard to improve surveillance of large asteroids around the Earth.
NASA is working on launching a new space telescope, the Near-Earth Object Surveyor, in 2026, though progress on this project has been slow and it has just received a budget cut.