NASA’s OSIRIS-REx mission brought samples from asteroid Bennu to Earth, revealing molecules essential for life and a history of saltwater. While these findings don’t show evidence of life, they suggest that conditions for life’s emergence were common in the early solar system, potentially increasing the chances of life forming on other planets and moons.
Nicky Fox from NASA stated that the OSIRIS-REx mission transforms our knowledge of the solar system’s origins. Asteroids, like Bennu, serve as time capsules of Earth’s history, and the samples are crucial for understanding the pre-life ingredients of our solar system.
Recent research includes the first detailed analyses of Bennu’s minerals and molecules, which OSIRIS-REx brought back to Earth in 2023.
Researchers found 14 out of 20 amino acids used by life on Earth and all five nucleobases in Bennu samples essential for making proteins and storing genetic information. They also discovered high ammonia levels, which can combine with formaldehyde to create amino acids. These findings indicate that objects far from the Sun may have provided crucial raw ingredients for life across the solar system.
Detecting these building blocks for life in pristine Bennu samples supports the idea that objects formed far from the Sun could be crucial sources of life’s raw ingredients. According to Danny Glavin from NASA, these minuscule clues could have been destroyed if exposed to Earth’s environment, highlighting the importance of the sample-return mission.
While Glavin’s team searched Bennu samples for life-related compounds, other scientists like Tim McCoy and Sara Russell examined the samples to uncover clues about the ancient environment where these molecules formed, providing further evidence of conditions conducive to the chemistry of life.
Scientists found 11 minerals in Bennu samples, including calcite, halite, and sylvite, that form when water with dissolved salts evaporates over time, leaving solid crystals. Similar brines have been detected on Ceres and Enceladus.
While evaporites have been found in meteorites, Bennu’s samples are unique as they preserve an evaporation process that could have taken thousands of years. Some minerals, like trona, were discovered for the first time in extraterrestrial samples.
These findings help explain how life’s ingredients may have come together on this water-altered asteroid.
Despite the insights gained from Bennu samples, some questions remain. Bennu samples contain an equal mix of left-handed and right-handed amino acids, while life on Earth predominantly produces the left-handed type. This suggests that early Earth might have started with an equal mixture. The reason life “turned left” is still unknown.
Jason Dworkin from NASA highlighted the success of the OSIRIS-REx mission, noting that it provides significant insights into the potential for life in the solar system. However, the question of why life has only been found on Earth remains unanswered.
Journal References:
- Glavin, D.P., Dworkin, J.P., Alexander, C.M.O. et al. Abundant ammonia and nitrogen-rich soluble organic matter in samples from asteroid (101955) Bennu. Nat Astron (2025). DOI: 10.1038/s41550-024-02472-9
- McCoy, T.J., Russell, S.S., Zega, T.J. et al. An evaporite sequence from ancient brine recorded in Bennu samples. Nature 637, 1072–1077 (2025). DOI: 10.1038/s41586-024-08495-6
