Nasa’s OSIRIS-REx spacecraft slingshot past Earth to hunt asteroid Bennu


Nasa’s Origins, Spectral Interpretation, Resource Identification, and Security - Regolith Explorer (OSIRIS-Rex) asteroid-hunting spacecraft has flown past Earth, using the planet’s gravity to slingshot itself towards its destination asteroid, Bennu.

Launched last September, the OSIRIS-Rex mission received the latest gravity boost when it came within 17,237km of Antarctica, south of Cape Horn, Chile.

The boost has forced the spacecraft to follow a new route north over the Pacific Ocean and has changed its velocity to 3.778km/s.

Bennu’s current orbit around the Sun is tilted 6° from Earth’s orbit, and the latest thrust has changed OSIRIS-Rex’s direction to manoeuvre it towards the asteroid.

Nasa Goddard Space Flight Centre Maryland OSIRIS-REx project manager Rich Burns said: “The encounter with Earth is fundamental to our rendezvous with Bennu.

“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 encounter with Earth is fundamental to our rendezvous with Bennu."

The recent flyby is also expected to help the Nasa mission team to test and calibrate OSIRIS-REx’s instrument suite.

Nearly four hours after the point of closest approach and on three subsequent days over the next two weeks, the spacecraft’s instruments are set to be turned on to scan Earth and the Moon.

The resulted data will be used to calibrate OSIRIS-REx’s science instruments to prepare the spacecraft for its planned arrival at Bennu by late next year. 

During its seven-year journey, the probe is expected to rendezvous with, study, and return a sample of Bennu to Earth.

The asteroid sample will be further examined by the scientists to understand the formation of the solar system in a better way.


Image: This artist's concept shows the OSIRIS-REx spacecraft passing by Earth. Photo: courtesy of Nasa's Goddard Space Flight Center/University of Arizona.