OSIRIS-REx begins its 7 year journey to 101955 Bennu

The OSIRIS-REx Mission launched from Cape Canaveral on September 8th. But what will the probe do?

By: Dhan P.

The Origins Spectral Interpretation Resource Identification Security – Regolith Explorer, better known by the acronym OSIRIS-REx, launched on September 8th, on a mission to return a sample of the asteroid 101955 Bennu. It is planned to reach Bennu in 2018 and is planned to return in 2023. The mission will help us learn more about the history of the solar system, and about the composition of asteroids, as well as studying other influences on them.

But why did NASA choose Bennu? Bennu is a type of asteroid known as a Near Earth Object (NEO). This means that its orbit takes near Earth’s orbit, (in this case within 0.002AU) which makes it ideal for a sample return mission. In addition, Bennu is over 200 meters in diameter, which makes it easier to orbit and makes sure all the loose dirt and rock hasn’t been flung off. Finally, Bennu is a relatively rare Type-B asteroid, which are carbon rich and have remained relatively unchanged since the formation of the solar system. Carbon rich asteroids also may contain key components of amino acids, which may have seeded life on earth.

The plan for OSIRIS-REx once it reaches the asteroid in 2018, is to image the surface of the asteroid to look for the most promising sampling sites for two years. It will use several cameras, first to zero in on the asteroid, and then scan the object in various ways, via visible light, infrared and x-rays. The actual sampling part of the mission will take place in July 2020. The probe will not land on the surface, but will use the Touch-and-go Sample Acquisition Mechanism (TAGSAM) to collect a sample of the loose dust and rock from the surface of Bennu. Once the sample is acquired, the probe will begin its journey back to Earth. In September of 2023, the probe will eject the capsule containing the sample and redirect itself into a stable orbit around the sun. The capsule will land in the Utah desert, where it will be collected and the contents examined.

The sample will help the scientific community understand how the bombardment of asteroids and comets would have affected how life started on our planet. Some hypothesize that the organic compounds found in the asteroids and comets that collided with Earth in the early solar system could have kickstarted life here. The sample from the probe will help us understand how the impacts would have helped or harmed life here.

The mission, in addition to returning material from an ancient object, will also include investigating the Yarkovsky effect. The Yarkovsky effect is the effect of the infrared radiation that asteroids emit on their orbit. The effect has been measured before, but OSIRIS-REx will make more measurements and observe the nuances of the effect.

osirisrextagprint2016.jpg

A visualization of the TAGSAM. (NASA)

Hopefully the entire mission goes according to plan, and we will have a sample of Bennu in 2023. You can read more about the mission at www.nasa.gov/osiris-rex and at www.asteroidmission.org.

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