Since the discovery of asteroids in space, all that scientists know about their characteristics is through telescope and satellite observations. For the first time, NASA's OSIRIS-REx spacecraft will attempt to collect the first asteroid surface sample from 101955 Bennu on October 20.

Bennu is a near-Earth asteroid that is believed to be a remnant of an ancient collision from the main asteroid belt. Investigating its surface samples would give researchers a better understanding of how planets formed, the origin of life and water, and the potential impact asteroid has on Earth.

Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) was launched in 2016 and has been orbiting asteroid Bennu for the past few years. This year's major task is to collect surface samples that will be returned to Earth by 2023. The spacecraft will attempt to collect at least two ounces of surface material.


Organic Materials on Bennu

In 2019, images of the asteroid revealed that Bennu's surface was covered in organic material that contains carbon. A study of the carbon-bearing findings led by Amy Simon from the Goddard Space Flight Center was recently published in the journal Science.

The carbon-bearing material is widespread throughout the whole asteroid, described the study, and will be collected at the sample site called Nightingale, where OSIRIS-REx will land. Simon's team believes that Bennu's geology is composed of carbonate minerals. These minerals typically come from hydrothermal systems composed of carbon dioxide and water present in Bennu's parent body.

Aside from possible signs of water and life on the asteroid, samples would confirm how cosmic bodies are affected by space weathering. Harsh conditions of space are combined with cosmic rays, high-energy atom fragments that move nearly at light-speed, and solar wind.

Evidence of space weathering will be revealed in sample colors. For example, surface materials exposed to space weathering for an intermediate period would be vivid blue while longer exposure would result in less intense blue.

OSIRIS-REx observations have also revealed the gravity field of the asteroid, its diamond-like shape, and how the north and south poles have different shapes. A study from the University of Colorado Boulder determined that Bennu's gravity field is not uniform due to the various trajectories of the asteroid's particles.

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Understanding the Origin of Life

Jason Dworkin from the Goddard Space Flight Center said that analyzing the surface sample after it arrives will give insight into the formation of the solar system. Moreover, it may provide new information on "the processes present at the dawn of the solar system, of planets, and of life."

New results of the spacecraft's observation revealed that pieces from asteroid Vesta landed on Bennu. Vesta is the brightest and second-largest asteroid in the main asteroid belt and is occasionally visible from Earth.

Daniella DellaGiustina from the University of Arizona said that six boulders from Vesta were found across Bennu's southern hemisphere and appeared brighter than the asteroid's surface materials in a recent study. It is believed that a Vesta fragment, called a vestoid, struck Bennu's parent asteroid and left debris on Bennu.

OSIRIS-REx's slow descent on Nightingale will last for about an hour. The sample collection on the surface will only last for about five seconds before it begins its journey back to Earth for the next three years.

Dworkin is hopeful that the sample will be rich in complex, organic compounds revealed from years of observations. The samples may have stories on the early formation of life on Earth and throughout the solar system.

Read Also: 73-Billion-Kilogram Asteroid Likely to Explode as It Continues to Spin at Increasing Speed


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