- NASA's Double Asteroid Redirection Test will collide with an asteroid on September 26.
- The DART mission is testing NASA's ability to deflect incoming space rocks.
- If it works, NASA could someday use this method to push dangerous asteroids away from Earth.
A golf cart-sized spacecraft will intentionally smash into a tiny asteroid at about 14,000 miles per hour on September 26. It's humanity's first test of our ability to deflect dangerous incoming space rocks.
NASA currently knows the location and orbit of roughly 28,000 nearby asteroids. To be clear, scientists have found no asteroid that poses an immediate threat to human civilization. But experts say that it's a matter of when — not if — Earth finds itself on track to be hit by one.
NASA's Double Asteroid Redirection Test (DART) mission launched atop a SpaceX Falcon 9 in November 2021, with the aim of nudging a space rock into a slightly tighter orbit around its companion asteroid. It's a test of whether such a nudge could one day divert a rogue space rock headed for Earth. The $308 million spacecraft traveled 6.8 million miles from Earth to Dimorphos, a small asteroid orbiting the asteroid Didymos.
"I'm highly confident that we are going to hit on Monday and that there will be a complete success," Lindley Johnson, NASA's first planetary defense officer, told reporters at a press conference on Thursday.
On Monday, September 26, four hours before impact, DART will switch into autonomous mode, steering itself toward its target. If all goes according to plan, the 1,376-pound spacecraft will collide with Dimorphos, altering its orbit around Didymos ever so slightly. Scientists expect the collision to change the speed of Dimorphos by a fraction of 1%.
(The asteroid's name, Dimorphos, is Greek for "having two forms" and was chosen because the asteroid will have one form before DART crashes into it, and another form after.)
Dimorphos is around 525 feet in diameter, and it orbits another, larger asteroid — the 2,650-foot-wide Didymos.
According to Elena Adams, a DART mission systems engineer, the team will know DART successfully smashed into Dimorphos when they lose the spacecraft's signal. "We'll all celebrate," Adams told reporters on Thursday.
The asteroid system poses no threat to Earth, according to NASA, making it the perfect target to test our ability to slam into asteroids, in order to change their orbit, and move them out of Earth's way.
NASA plans to film the collision
While the spacecraft will not survive the encounter, its single science instrument — the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO) — will be switched on for the death dive, taking one image per second to document the impact and aftermath.
"We are excited for what DRACO will reveal about Didymos and Dimorphos in the hours and minutes leading up to impact," Carolyn Ernst, DRACO instrument scientist at APL, said in a press release.
About three minutes or so after the collision, a shoebox-sized CubeSat developed by the Italian Space Agency, the LICIACube, will be taking high-resolution images of the event. On September 11, the CubeSat left the spacecraft and is now at a safe distance of about 34 miles from the surface of Dimorphos.
A live stream of images captured by the spacecraft will be available on NASA's website beginning at 5:30 p.m. ET on Monday, September 26. The impact is expected to occur around 7:14 p.m. ET.
"Even after DART is gone, images traveling through space will continue to come back for about eight seconds," Ed Reynolds, DART's project manager, told reporters on Thursday.
What's next after DART's deliberate crash
Once DART has been destroyed during the collision, follow-up observations with ground- and space-based telescopes will evaluate the asteroid system to see how much its orbit changed.
The mission's data will provide astronomers with important information about how well spacecraft could protect Earth from an incoming asteroid, and inform any adjustments that need to be made to the probe.
Two years after DART's collision with Dimorphos, the European Space Agency will launch a mission called Hera to study Didymos and Dimorphos in depth. By observing the deformations caused by the impact, the spacecraft aims to gain a better understanding of Dimorphos' composition and formation.