A NASA spacecraft is on the final leg of its journey back to Earth after collecting samples from asteroid Bennu.
The OSIRIS-REx mission successfully selected samples of the asteroid in 2020. It is set to return to Earth on September 24, 2023. But why was asteroid Bennu chosen for such an important mission? Here is everything we know about the asteroid that could hold clues into the origin of our solar system.
Bennu is a 1,600-foot-wide near-Earth asteroid that was discovered in 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) Project. It passes by Earth approximately every 6 years.
However, there is something special about this asteroid. And there are several reasons why scientists chose it as the subject for the OSIRIS-REx mission.
Firstly, this asteroid has an average orbital distance from the sun of around 105 million miles. This is relatively close to that of the Earth at 93 million miles.
It is also a B-type asteroid. These types of carbonaceous asteroids are rare and incredibly old. Scientists believe Bennu was formed over 4.5 million years ago and that it's incredibly rich in carbon, which might contain organic compounds. This means that it could carry chemicals and rocks that date back to the birth of the solar system.
James Bryson, an associate professor of mineralogy at the Department of Earth Sciences at the University of Oxford, told Newsweek: "Bennu is a small asteroid that is relatively close to Earth. This means we can visit it comparatively easily using space missions, enabling us to touch down on the asteroid and retrieve material to bring back to Earth. Importantly, the observations we have of Bennu suggest it is similar to meteorites that have landed on Earth that contain about 10 percent water. As such, if a Bennu-like object collided with the early Earth, it would have delivered a large amount of water and other life-critical molecules, which is currently the preferred model of how Earth became habitable. The material returned from Bennu will allow us to explore this model with a new level of depth and clarity, so will uncover new insights into the origins of life on planets."
Bennu was likely formed from breaking off from a much larger, carbon rich asteroid around 700 million to 2 billion years ago, according to NASA. It likely came to be in the main asteroid belt that lies between Jupiter and Mars.
The OSIRIS-REx spacecraft arrived at Bennu on December 3, 2018, following a two year journey. From there, it orbited Bennu, analyzing its surface to determine potential collection sites for the sample needed.
The spacecraft eventually landed on the asteroid on October 20, 2020, and collected pristine samples using its extendable arm. It then prepped for its long journey back to Earth with the samples, departing from the asteroid on May 10, 2021.
"This is one of the first times that a space agency has returned material from an asteroid," Bryson said. "This means we will be able to link observations measured in the laboratory (once the material has been brought to Earth) with observations of the asteroid itself from telescopes and from the instruments on the satellite. This is a new level of detail that we have very rarely achieved previously, and will afford us a particularly deep level of insight that could help to uncover the process by which Earth became habitable."
Bennu is not just notable for the clues it may hold into the early solar system. But it is officially one of the most likely asteroids to collide with Earth at some point in the next thousand years. Luckily, the odds of this actually happening are very low.
In August of 2021, NASA predicted in a study that the likelihood of Bennu colliding into Earth is about 1 in 1,750.
Bennu orbits at an average speed of 63,000 miles per hour. Once close to Earth, it takes around 1.2 years to orbit the sun fully, and rotates once every 4.3 hours.
Scientists hope to continue looking into the asteroid even after these samples are received since it's expected to pass close to Earth in 2037. During this time, scientists hope to further analyze its impact risk.
It is not the first time that scientists have analyzed asteroid samples for clues into the creation of the solar system.
Last August, a study published in Nature Astronomy, presented the findings from Japanese Hayabusa2—a mission conducted in 2019 by Japanese state space agency JAXA to retrieve samples from the asteroid Ryugu.
The spacecraft returned to Earth in 2020 after extracting 5 grams of particles from the asteroid. A team of researchers from the Japan Agency for Marine-Earth Science and Technology found the particles from the asteroid were like no other. According to the study, the particles were "pristine" and offer never before seen clues about the solar system.
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Uncommon Knowledge
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
About the writer
Robyn White is a Newsweek Nature Reporter based in London, UK. Her focus is reporting on wildlife, science and the ... Read more
