Searching for Earth’s Trojan Asteroids

Trojan asteroids are common at the L4 and L5 Lagrange points of other planets, leading or following the planet in its orbit. But detecting our own Trojan asteroids from Earth is difficult since they appear close to the sun from our perspective. In mid-February 2017, NASA's OSIRS-REx mission will search for these elusive objects when the spacecraft passes by Earth's L4 Lagrange point, en route to asteroid Bennu in 2018. Jim Green, the Director of Planetary Science at NASA, discusses OSIRIS-REx and its search for Earth's Trojan asteroids.