As it heads outward for a rendezvous with the asteroid Bennu, OSIRIS-REx will turn on its instruments for 12 days in February 2017 to hunt for the Trojan asteroids that likely orbit the Sun in the Earth’s orbit 60 degrees ahead and behind it.
Six planets in our solar system are known to harbor Trojan asteroids — Jupiter, Neptune, Mars, Venus, Uranus and Earth. Although more than 6,000 Trojan asteroids are known to be orbiting along with Jupiter, scientists have discovered only one Earth Trojan to date: 2010 TK7, found by NASA’s NEOWISE project in 2010. Scientists predict that there should be more Trojans orbiting Earth, but these asteroids are difficult to detect because they appear close to the sun from Earth’s point of view. In mid-February 2017, however, the OSIRIS-REx spacecraft will be ideally positioned to undertake a survey of the stable point in front of Earth.
Over 12 days, the OSIRIS-REx Earth-Trojan asteroid search will employ the spacecraft’s MapCam imager to methodically scan the space where Earth Trojans are expected to exist. MapCam is part of the OSIRIS-REx Camera Suite, or OCAMS, which was designed and built by researchers at the UA’s Lunar and Planetary Laboratory.