NASA scientists used a slingshot manoeuvre around the Earth in their mission to land a spacecraft on an asteroid.
Returning to the planet almost a year after its launch, the probe came within 10,711 miles (17,237 km) of Antarctica, before following a route north over the Pacific Ocean.
The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) has the mission of studying asteroid 101955 Bennu.
OSIRIS-REx was launched on the back of an Atlas V rocket from the Cape Canaveral Air Force Station on 8 September 2016.
It will be the first spacecraft to land on an asteroid and return a sample to Earth if its mission is a success, and it has now completed a carefully calibrated slingshot move around Earth which will let it land on Bennu.
The rocket gave OSIRIS all the momentum it required to reach Bennu, but it needed to use Earth’s gravity to swing towards the asteroid.
As a result of the flyby, the velocity change to the spacecraft was 8,451 miles per hour (3.778 kilometers per second), according to NASA.
“The encounter with Earth is fundamental to our rendezvous with Bennu,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Centre.
“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.”
The mission team also used the flyby to test out OSIRIS-REx’s suite of scientific instruments.
Just after four hours of the point of closest approach, and on three subsequent days over the next two weeks, these instruments will be turned backwards to scan the Earth and the Moon.
OSIRIS-REx will arrive at Bennu in late 2018 and subsequently return samples to Earth in 2023 for analysis.
The sample of the primitive asteroid is hoped to help scientists understand the formation of the Earth’s solar system 4.5 billion years ago.