OSIRIS-REx begins hunt for elusive ‘Trojan’ asteroids

Joe Latrell

After successfully launching in September of last year (2016), OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) has been given a new task – to hunt for “Trojan” asteroids that may pose a danger to Earth.

Trojans are rocky or metallic asteroids that orbit in stable areas called Lagrange points. Specifically, they are located 60 degrees ahead or behind the host body in its orbit around the Sun: L-4 and L-5. Asteroids in these gravity pockets can remain in the same orbit undisturbed for centuries.

Six planets are known to have these asteroids, with Jupiter’s being the most famous. So far, only one Earth trojan has been discovered, but it is likely there are dozens, possibly hundreds, more of these celestial objects.

The danger from these types of asteroids is that because of their orientation between the Earth and the Sun, they are very difficult to locate and track.

According to a report appearing on Nature World News, some scientists think that a Mars-sized trojan object collided with Earth, creating a cloud of debris that eventually formed the Moon. This collision is also thought to potentially be responsible for Earth’s over-sized core.

In order to effectively detect trojans, you need to get the observing device away from Earth. OSIRIS-REx does just this as it makes its way to Bennu, a primitive asteroid whose 1.2-year orbit brings it within Earth’s path.

OSIRIS-REx will use its MapCam to look in the areas where these objects are most likely to reside and catalog their locations. This is the same instrument scientists plan to use at Bennu to look for small satellite objects around the asteroid. Here, the MapCam will pull double duty as the two processes are very similar.

The primary mission of the spacecraft is to study Bennu and return a sample back to Earth. The mission will arrive at the asteroid in 2018.

According to SpaceFlight 101, using a device called TAGSAM (Touch-And-Go-Sample Acquisition Mechanism), OSIRIS-REx will collect a small sample and then bounce off the surface of the asteroid. The spacecraft is then scheduled to return that sample to Earth in 2023.

Detailed studies of the asteroid will also help determine if Bennu is a potential threat to Earth as some orbital models show a possible impact occurring sometime next century.

OSIRIS-REx was sent on its way toward Bennu via a United Launch Alliance Atlas V 411 rocket on Sept. 8, 2016, from Cape Canaveral Air Force Station Space Launch Complex 41 in Florida.