NASA’s Bennu asteroid sample contains life’s essential ingredients

In a remarkable advancement in the field of space exploration, NASA’s OSIRIS-REx mission has brought back invaluable samples from the asteroid Bennu to Earth. This mission, formally known as the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer, has unearthed intriguing discoveries that could reshape our understanding of life’s origins and the early solar system.

The analysis of the rocks and dust retrieved from Bennu has uncovered molecules that are vital to life on Earth. Additionally, there is evidence suggesting the past presence of salty water on Bennu, which could have served as a medium for these molecules to interact and merge. While these findings do not point to actual life forms, they do suggest that the conditions necessary for life were prevalent throughout the early solar system. This increases the possibility that life might have emerged on other planets and moons as well.

Nicky Fox, associate administrator for NASA’s Science Mission Directorate in Washington, expressed the significance of these findings. She stated, "NASA’s OSIRIS-REx mission is already rewriting our understanding of the early solar system’s beginnings. Asteroids serve as a time capsule of our home planet’s history, and Bennu’s samples are crucial for comprehending which ingredients in our solar system existed before life began on Earth."

The research and its results were shared in the distinguished journals Nature and Nature Astronomy. Scientists from NASA and other institutions conducted detailed analyses of the minerals and molecules found in Bennu’s samples, which were returned to Earth by the OSIRIS-REx spacecraft in 2023.

Among the significant detections, as detailed in Nature Astronomy, are amino acids, which are the building blocks of proteins in terrestrial life, and nucleobases, which are essential for storing and transmitting genetic information in complex biological molecules like DNA and RNA. These findings highlight the presence of the fundamental components necessary for life as we know it.

In addition, the samples from Bennu showed exceptionally high levels of ammonia, an important compound in biology. Under the right conditions, ammonia can react with formaldehyde, which was also detected in the samples, to form complex molecules like amino acids. When amino acids connect in long chains, they form proteins, which are crucial for nearly all biological functions.

These building blocks of life discovered in Bennu’s samples have been found in extraterrestrial rocks before. However, identifying them in a pristine sample obtained from space supports the idea that objects formed far from the Sun could have been a significant source of the basic precursor ingredients for life throughout the solar system.

Danny Glavin, the lead sample scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, emphasized the importance of these discoveries. He noted, "The clues we are seeking are incredibly tiny and can be easily destroyed or altered when exposed to Earth’s environment. This is why some of these new findings wouldn’t be possible without a return mission bringing back the samples, meticulous contamination control measures, and careful curation and storage of this precious material from Bennu."

While Glavin’s team focused on identifying life-related compounds in Bennu’s samples, other scientists, like Tim McCoy, meteorite curator at the Smithsonian Institution’s National Museum of Natural History, and Sara Russell, a cosmic mineralogist at the Natural History Museum in London, sought clues about the environment where these molecules might have formed. Their findings, published in the journal Nature, describe evidence of a primordial environment that could have kick-started the chemistry of life.

The study found traces of 11 minerals in Bennu’s samples, such as calcite, halite, and sylvite. These minerals form as water containing dissolved salts evaporates over long periods, leaving behind the salts as solid crystals. Such brines have been detected or suggested to exist throughout the solar system, including on the dwarf planet Ceres and Saturn’s moon Enceladus.

Although scientists have previously detected various evaporites in meteorites that fall to Earth, they have never observed a complete set of sedimented salts preserving an evaporation process that could have lasted thousands of years or more. Some minerals present in Bennu, like trona, were discovered for the first time in extraterrestrial samples.

McCoy remarked on the complementary nature of these scientific articles, saying, "These scientific papers really complement each other in trying to explain how the ingredients of life came together to form what we see in this aqueously altered asteroid."

Despite the answers provided by Bennu’s sample, several questions remain. Many amino acids can exist in two mirror-image versions, like a pair of left and right hands. Life on Earth almost exclusively produces the left-handed (or counterclockwise) variety. However, Bennu’s samples contain an equal mix of both. This suggests that, in early Earth, amino acids might have also started with an equal mix. Why life "chose" the left-handed version remains a mystery.

Jason Dworkin, a scientist working on the OSIRIS-REx project at NASA’s Goddard Center, highlighted the mission’s success by stating, "OSIRIS-REx has been a highly successful mission. The data from OSIRIS-REx adds broad strokes to a picture of a solar system brimming with potential for life. Why do we, so far, only see life on Earth and not elsewhere? That is the truly captivating question."

The OSIRIS-REx mission, managed by NASA’s Goddard Space Flight Center, involved collaboration with various institutions. The University of Arizona in Tucson led the scientific team, while Lockheed Martin Space in Littleton, Colorado, built the spacecraft and managed flight operations. NASA’s Johnson Space Center in Houston curated the samples, and international partners contributed to the mission’s success.

For more information about the OSIRIS-REx mission, visit the official NASA website: NASA OSIRIS-REx.

This groundbreaking mission exemplifies the power of scientific exploration and international collaboration. It not only enhances our understanding of the early solar system but also raises intriguing questions about the potential for life beyond our planet.

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