On Sept. 26, the Double Asteroid Redirection Test (DART) spacecraft collided with the tiny asteroid Dimorphos. Dimorphos' orbit around a larger asteroid was intended to be shortened by DART by at least 73 seconds, although scientists believed the effect would be closer to 10 minutes.
DART, however, outperformed those benchmarks, cutting Dimorphos' approximately 12-hour orbit by a staggering 32 minutes, NASA officials reported at a news briefing on Monday (Oct. 11).
"Let's all just kind of take a moment to soak this in," Lori Glaze, head of NASA's planetary science division, said during the news conference. "For the first time ever, humanity has changed the orbit of a planetary body, of a planetary object. First time ever."
The mission was designed to test a potential planetary defense mechanism in the event that a massive space rock collides with Earth, while NASA is aware of no such dangers in the near future.
The DART spacecraft launched in November 2021 with a single instrument - a Didymos Reconnaissance and Asteroid Camera for Optical Navigation camera (DRACO). The spacecraft then traveled to Dimorphos, which scientists believed was roughly 525 feet broad, and orbited a larger asteroid called Didymos every 11 hours and 55 minutes.
On Sept. 26, DART made its arrival. That was the project's first success, but the evening also provided early indications that the mission would exceed expectations on all fronts.
Dimorphos' disrupted orbit is the mission's primary discovery to date, but presenters at the press briefing also showed fresh pictures of the impact's aftermath.
On Saturday, NASA also released a picture of Dimorphos captured by the Hubble Space Telescope. The image depicts a broad cone of debris that, in comparison to prior pictures of the collision's aftermath, the sun has slightly collapsed on one side.
The extended tail of debris, which extends 6,000 miles into space, can also be seen in the Hubble image. The latest image reveals that the tail has split into two since earlier photographs; researchers are still trying to determine what caused the fork.
The 32-minute change disclosed today comes with a two-minute uncertainty zone on either side, which scientists plan to limit even further. Scientists are probing for any potential orbital wobbles caused by the hit.
The mission's observations will continue throughout the next year. The European Space Agency will also deploy a follow-up spacecraft, Hera, in 2024 to investigate Didymos and Dimorphos in greater depth than DART could on its brief visit.
