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NASA mission searches for 'trojan' asteroids

Posted February 9

The OSIRIS-REx is performing other science observations during the 2 year cruise phase to its primary mission (Credit: University of Arizona)

Thursday, the OSIRIS-REx Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) mission will reach the L4 region.

OSIRIS-REx is NASA’s first mission to return a sample of an asteroid to Earth. This sample of a primitive asteroid will help scientists understand the formation of our solar system more than 4.5 billion years ago.

During its two-year outbound cruise to asteroid Bennu, named in a NASA contest by a Greensboro elementary student, OSIRIS-REx will perform a number of additional tasks. First on the list is a search for elusive Earth trojan asteroids.

Trojans are asteroids orbiting near a stable point 60 degrees in ahead of or behind a planet. Despite the ominous sounding name, trojan asteroids are benign. Because they constantly lead or follow in the same orbit, there is no danger of collision with their companion planet.

There are known trojans in the orbits of Jupiter, Neptune, Mars, Venus, Uranus and Earth. Jupiter has more than 6,000 Trojans while a single Trojan was discovered in 2010 leading Earth around the Sun.

OSIRIS-REx will spend 12 days in the region of L4, or Lagrange point four. Lagrange points are equilibrium in space where the gravitational pull of two large bodies (such as the Sun and Earth) combine to hold another small body (such as an asteroid or spacecraft) in a stable orbit.

The spacecraft’s MapCam imager will scan this area where Earth Trojans are expected to exist.


“Not only do we have the opportunity to discover new members of an asteroid class, but more importantly, we are practicing critical mission operations in advance of our arrival at Bennu, which ultimately reduces mission risk.” said OSIRIS-REx Principal Investigator Dante Lauretta of the University of Arizona, Tucson.

Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.


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