Sept. 22 (UPI) -- NASA's OSIRIS-REx probe has used Earth's gravity to slingshot itself into outer space. The spacecraft is now en route to the asteroid Bennu and is expected to encounter the space rock in August 2018.
On Friday, OSIRIS-REx swung past the South Pole at an altitude of 10,711 miles. During the flyby, Earth's gravity offered the probe's speed a boost of 8,451 mph.
OSIRIS-REx, short for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer, is NASA's asteroid encounter and sample collection mission.
Once OSIRIS-REx meets up with Bennu, the probe will circle the asteroid for nearly two years. In 2020, the probe will attempt to scoop up rock and dust samples from the surface of the asteroid. The spacecraft will begin its return journey to Earth in 2021 and is scheduled to touch down on September 24, 2023.
"The encounter with Earth is fundamental to our rendezvous with Bennu," Rich Burns, OSIRIS-REx project manager at NASA's Goddard Space Flight Center, said in a news release. "The total velocity change from Earth's gravity far exceeds the total fuel load of the OSIRIS-REx propulsion system, so we are really leveraging our Earth flyby to make a massive change to the OSIRIS-REx trajectory, specifically changing the tilt of the orbit to match Bennu."
Friday's flyby also offered OSIRIS-REx scientists a chance to test and calibrate the probe's instruments. For the next three weeks, the probe's instruments will survey Earth and the moon, allowing for further calibration.
"The opportunity to collect science data over the next two weeks provides the OSIRIS-REx mission team with an excellent opportunity to practice for operations at Bennu," said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. "During the Earth flyby, the science and operations teams are co-located, performing daily activities together as they will during the asteroid encounter."
OSIRIS-REx launched in September 2016. Scientists hope the probe's rendezvous with and sampling of 101955 Bennu will offer insights into the nature of the early solar system.
The 1,614-foot-wide space rock belongs to a collection of near-Earth asteroids known as the Apollo group. NASA scientists chose 101955 Bennu for the OSIRIS-REx mission because of its unique supply of unadulterated carbonaceous material, one of the building blocks of life. Researchers believe asteroid collisions may have provided early Earth with the biochemicals necessary for life.