OSIRIS REx swings by Earth en route to asteroid Bennu, using Earth's gravity like a slingshot to hurl the spacecraft onward to its destination. In mid 2018 it will orbit and sample the carbonaceous space rock before returning to Earth in 2023.
OSIRIS REx (The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) was launched on Sep 8, 2016. The sample of Bennu will help scientists understand the formation of the solar system more than 4.5 billion years ago, and provide a better understanding of asteroids that might impact Earth. Bennu is one of the most potentially hazardous asteroids, as it has a relatively high probability of impacting the Earth late in the 22nd Century, according to NASA.
The mission also has commercial potential as asteroids like Bennu contain natural resources such as water, organics, and precious metals. NASA notes that in the future, these asteroids may one day fuel the exploration of the solar system by robotic and manned spacecraft.
Lessons learned from the European Rosetta mission have helped hone the OSIRIS REx mission.
The mission has a dual purpose. It will also survey Earth's Trojan asteroids, bodies that are constant companions to planets in the solar system as they orbit the Sun. They remain at a near a stable point 60 degrees in front of, or behind, the planet.
Date written/update: 2017-01-04