NASA scientists announce Bennu asteroid sample contains carbon and water

A view of the outside of the OSIRIS-REx sample collector. Sample material from asteroid Bennu can be seen on the middle right. The bulk of the sample is located inside. (Image courtesy: NASA)

The first asteroid sample collected in space and brought to Earth by the United States was unveiled at NASA’s Johnson Space Center in Houston on October 11. Scientists of the American space agency have announced that initial studies show Bennu has "high carbon content and water".

"Sample that contain abundant water in the form of hydrated clay minerals and they contain carbon and organic molecules and at nearly 5 percent carbon by weight, carbon being the central element of life, far exceeding our goal of 60 grams," NASA administrator Bill Nelson said in a news conference sharing a first glimpse of the sample with the world.

"This is the biggest ever carbon-rich asteroid sample returned to earth. The carbon and water molecules are exactly the kind of materials that we wanted to find. They are crucial elements in the formation of our planet and they will help us to determine origin of elements that could have led to life," Nelson said.

"Who we are, what we are, and where we came from. What is our place in this vastness called the Universe? This mission will help scientists investigate."

The team of scientists presented images of the sample, revealing the presence of water-bearing clay minerals.

According to Dante Lauretta, OSIRIS-REx principal investigator, University of Arizona, Tucson, the bounty of carbon-rich material and the abundance of water-bearing clay minerals are just the tip of the cosmic iceberg. "These discoveries, made possible through years of dedicated collaboration and cutting-edge science, propel us on a journey to understand not only our celestial neighborhood but also the potential for life’s beginnings. With each revelation from Bennu, we draw closer to unraveling the mysteries of our cosmic heritage.”

Sample capsule reached Earth on Sep 24

NASA's OSIRIS-REx spacecraft (Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer), successfully delivered materials obtained from the Bennu asteroid to Earth on September 24. Upon its arrival in the earth's atmosphere, the sample return capsule was made to land at the Department of Defense's Utah Test and Training Range by parachute. The touchdown at Utah marked the end of a seven-year journey to OSIRIS-REx. The pristine material from Bennu was collected from Utah and was flown the next day to NASA’s Johnson Space Center, where a new curation facility has been built for the long-term study of the sample.

What is the composition of Bennu?

Bennu is a carbon-rich, near-Earth asteroid that is made up of rocks that formed 1 billion years ago when it broke off from its larger “parent” asteroid by the force of an impact. Within these rocks, there are traces of organic compounds and minerals, indicating that the parent asteroid likely had a history of liquid water. Additionally, the materials on Bennu show evidence of having undergone chemical changes due to interactions with liquid water in the past.

Scientists await clues to Solar System's origins

As per NASA, asteroids such as Bennu played a vital role in delivering water and organic compounds to Earth through their collisions with our planet billions of years ago. Scientists aim to study this era and its potential connection to the origins of life. The material extracted from asteroid Bennu promises to offer insights into the period approximately 4.5 billion years ago when the Sun and planets were forming. In essence, Bennu possesses the potential to unravel the mysteries of life's beginnings on Earth.

Every few years, Bennu flies relatively close to Earth. There is a very small chance of it hitting Earth next century. Therefore, studying Bennu provides invaluable insights that can aid us in developing preparedness measures for potential asteroid impacts.

What will scientists do now?

More than 200 scientists from across the world will collaborate to investigate the properties of the Bennu sample. This group includes researchers from U.S. institutions, NASA partners such as JAXA (Japan Aerospace Exploration Agency) and CSA (Canadian Space Agency). In the coming two years, these teams will undertake the critical task of documenting the sample and performing the necessary analyses to fulfill the mission's scientific objectives. Notably, a portion of the sample will be set aside for future research, utilising technologies that are yet to be developed in the years to come. Six months from now, a sample catalog will be made available to the public.

Key dates of the mission

OSIRIS-REx embarked on its mission on September 8, 2016. It reached the asteroid Bennu on December 3, 2018. The crucial sample collection from Bennu was gathered on October 20, 2020. The return journey to Earth began on May 10, 2021. Finally, on September 24, 2023, the sample capsule was safely returned to Earth.