Spaceflight Insider

OSIRIS-REx begins search for Earth-Trojan asteroids

An artist’s rendering of the OSIRIS-REx spacecraft’s survey pattern during its Earth-Trojan Asteroid Search (not to scale). The search occurs Feb. 9-20, 2017, as the spacecraft transits the Earth’s L4 Lagrangian region. Image Credit: University of Arizona

An artist’s rendering of the OSIRIS-REx spacecraft’s survey pattern during its Earth-Trojan asteroid search (not to scale). The search started on Feb. 9, 2017, and will continue until Feb. 20, 2017, as the spacecraft transits the Earth’s L4 Lagrangian region. Image Credit: University of Arizona

On Feb. 9, NASA’s OSIRIS-REx spacecraft began searching for an elusive type of near-Earth object known as Earth-Trojan asteroids. The spacecraft, currently on a two-year outbound journey to the asteroid Bennu, will spend nearly two weeks looking for evidence of these small bodies.

trojan asteroid search

OSIRIS-REX searches for elusive Earth-Trojan asteroids in Earth’s L4 Lagrange point. Image Credit: NASA

Trojan asteroids are trapped inside stable gravity wells called Lagrange points, which precede or follow a planet as it orbits the Sun. The OSIRIS-REx spacecraft is currently traveling through Earth’s fourth Lagrange point (L4), which is approximately 90 million miles (150 million kilometers) away.

The mission team will take multiple images of the area with OSIRIS-REx’s MapCam camera in the hope of detecting Earth-Trojan asteroids in the region.

While researchers have discovered only one Earth-Trojan to date, asteroid 2010 TK7, thousands of Trojan asteroids have been found accompanying other planets, mostly around Jupiter. Researchers predict that there should be more Trojans sharing Earth’s orbit, but they are hard to find from Earth because they appear near the Sun on the horizon.

“Because the Earth’s fourth Lagrange point is relatively stable, it is possible that remnants of the material that built Earth are trapped within it,” said Dante Lauretta. “So this search gives us a unique opportunity to explore the primordial building blocks of Earth.”

Each day during the search, OSIRIS-REx’s MapCam will take 135 survey images that will be processed and analyzed by the mission’s imaging team at the University of Arizona, Tuscon. During the survey, MapCam will also image Jupiter, several galaxies, and main belt asteroids 55 Pandora, 47 Aglaja, and 12 Victoria.

The search will continue until Feb. 20.

The survey will be beneficial even if no new asteroids are discovered as the operations involved in searching for Trojans are similar to those required to search for natural satellites and other hazards around Bennu when the spacecraft approaches it in 2018.

Practicing these kinds of mission-critical operations in advance will help OSIRIS-REx once the spacecraft arrives at Bennu.

Video courtesy of NASA / University of Arizona 

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Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.

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