Next week, on October 20 if all goes well, NASA’s OSIRIS-REx spacecraft will make its long-awaited attempt to extract samples from Bennu´s surface. Bennu is a small near-Earth asteroid discovered in 1999 by the LINEAR Project. Bennu is known for being the second most dangerous asteroid on the Palermo Technical IMpact Hazard Scale, having a 1-2700 chance of impacting Earth in the next century. Its diameter is 490 meters across.

OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) will study the asteroid and attempt a sample-return mission. The sample of about 60 grams will be extracted on October 20th. While the spacecraft was launched on 8 September 2016, its return is only expected on 24 September 2023.

NASA’s OSIRIS-REx mission readies itself to touch the surface of asteroid Bennu
NASA’s OSIRIS-REx mission readies itself to touch the surface of asteroid Bennu.
Credits: NASA/Goddard/University of Arizona

Bennu was selected because it has been suspected to have been around since the birth of our solar system. Asteroids like Bennu have had little geological change in the last billions of years. Making it an ideal time capsule to study early formations of planets and asteroids. The latest research indicates that scientists assume that they will find carbonates, building blocks of organic molecules less, on Bennu´s surface.

“One of the driving points of this mission is that these asteroids could have delivered some of the precursor organic matter that gave rise to [life on] Earth,” Kaplan told Popular Science.

“The abundance of carbon-bearing material is a major scientific triumph for the mission,” Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson, said in a NASA statement. “We are now optimistic that we will collect and return a sample with organic material – a central goal of the OSIRIS-REx mission.”

By analyzing the results from OSIRIS-REX´s visible and infrared spectrometer they have found vein-like structures of carbonate on the surface of Bennu. Carbonate is often found in water on Earth. This gives rise to the assumption that the proto-planet Bennu is thought to have been once part of could have hosted a “asteroid-scale hydrothermal system of water¨. In other words, this would be the astroid-equivalent of rivers.

“If the veins on Bennu are carbonates, fluid flow and hydrothermal deposition on Bennu’s parent body would have occurred on kilometer scales for thousands to millions of years,” the team led by Hannah Kaplan from NASA’s Goddard Space Flight Center, concluded in their paper.

OSIRIS-REX´s sample return mission will be broadcasted live on NASA´s website.


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