After nearly five years in space, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) spacecraft is on its way back to Earth with an abundance of rocks and dust from the near-Earth asteroid Bennu, the US space agency said.

The spacecraft is due to reach Earth on September 24, 2023, after orbiting the Sun twice.

On Monday, May 10, at 4.23 p.m. EDT, the spacecraft fired its main engines full throttle for seven minutes — its most significant manoeuvre since it arrived at Bennu in 2018.

This burn thrust the spacecraft away from the asteroid at 600 miles per hour (nearly 1,000 km per hour), setting it on a 2.5-year cruise towards Earth, NASA said.

After releasing the sample capsule, OSIRIS-REx will fire its engines to fly by Earth safely, putting it on a trajectory to circle the sun inside of Venus’ orbit.

“OSIRIS-REx’s many accomplishments demonstrated the daring and innovate way in which exploration unfolds in real time,” said Thomas Zurbuchen, associate administrator for science at NASA Headquarters, in a statement.

“The team rose to the challenge, and now we have a primordial piece of our solar system headed back to Earth where many generations of researchers can unlock its secrets,” he added.

OSIRIS-REx exceeded many expectations. Most recently, in the midst of a global pandemic, the team flawlessly executed the most mission’s critical operation, collecting more than 2 ounces (60 grams) of soil from Bennu’s surface.

The mission was instrumental in both confirming and refuting several scientific findings. Among those confirmed was a technique that used observations from Earth to predict that the minerals on the asteroid would be carbon-rich and show signs of ancient water. One finding that proved unsuccessful was that Bennu would have a smooth surface, which scientists predicted by measuring how much heat radiated off its surface, NASA said.

Scientists will use the information gleaned from Bennu to refine theoretical models and improve future predictions.

“This mission emphasises why we have to do science and exploration in multiple ways — both from Earth and from up-close in space — because assumptions and models are just that,” said Heather Enos, OSIRIS-REx deputy principal investigator, based at the University of Arizona, Tucson.