THE OSIRIS-REx – Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer

Osiris-Rex is a NASA probe sent to collect rock from an asteroid several hundred million kilometres from Earth. The mission’s primary goal is to obtain a sample of at least 60 g (2.1 oz) from Bennu, a carbonaceous near Earth asteroid and return the sample to Earth for a detailed analysis.

Watch sample collection as seen by the navigation camera by Osiris-Rex.

The material returned is expected to enable scientists to learn more about the formation and evolution of the Solar System, its initial stages of planet formation and the source of organic compounds that led to the formation of life on Earth. OSIRIS-REx was launched on 8 September 2016, flew past Earth on 22 September 2017, and rendezvoused with Bennu on 3 December 2018. It has since spent the next several months analyzing the surface to find a suitable site from which to extract a sample. On 12 December 2019, NASA announced the first sampling site, known as Nightingale.

On 20 October 2020, OSIRIS-REx approached Bennu and successfully executed the steps to collect a sample. It is expected to return with its sample to Earth on 24 September 2023. Unfortunately, the flap that should have closed the sampler head after collection was jammed open by larger rock samples, allowing some of the collected sample to leak out after collection. Nonetheless, NASA is confident that they were able to retain somewhere between 400 g and over a kg – well in excess of the 60 g (2.1 oz) minimum target mass.

Why Bennu?

Bennu was chosen as the target of study because it is a “tme capsule” from the birth of the Solar System. Bennu has a very dark surface and is classiifed as a B-type asteroid, a sub-type of the carbonaceous C-type asteroid. Such asteroids are considered “primitive”, having undergone little geological change from their time of formation. In particular, Bennu was selected because of the availability of pristine carbonaceous material, a key element in organic molecules necessary for life as well as representative of matter from before the formation of Earth. Organic molecules, such as amino acids, have previously been found in meteorite and comet samples, indicating that some ingredients necessary for life can be naturally synthesized in outer space.

The cost of the mission is approximately US$800 million, not including the Atlas V launch vehicle, which is about US$183.5 million. It is the third planetary science mission selected in the New Frontiers program, after Juno and New Horizons. The principal investigator is Dante Lauretta from the University of Arizona. If successful, OSIRIS-REx will be the first United States spacecraft to return samples from an asteroid.

The samples will only be examined after the spacecraft completes its long journey home – it will touch down in September 2023.

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