NASA scientists have uncovered essential ingredients for life in the Bennu asteroid sample, offering new insights into the origins of life in the solar system. The sample, returned to Earth in September 2023 by the OSIRIS-REx mission, contains amino acids, nucleobases, and other organic molecules, reinforcing theories that life’s building blocks may have arrived on Earth from space.
A Treasure Trove of Organic Molecules
The discovery, published in Nature and Nature Astronomy, reveals that the Bennu sample contains 14 of the 20 amino acids that form proteins on Earth. Even more intriguing, the sample includes nucleobases, the fundamental components of DNA and RNA, the molecules responsible for genetic information in all known life forms.
These findings do not confirm extraterrestrial life, but they do suggest that prebiotic chemistry—the kind of chemical reactions that might have led to life—was widespread in the early solar system. If the conditions for life existed on ancient asteroids like Bennu, it’s possible they existed elsewhere, increasing the odds that life could have formed on other planets or moons.
The Role of Water in Bennu’s Past
One of the most intriguing aspects of the study is the presence of 11 different minerals, including calcite, halite, and sylvite, all of which indicate past interactions with liquid water. These minerals suggest that Bennu, or its parent asteroid, had conditions that could have helped complex molecules interact and evolve.
NASA scientists believe that Bennu originated from a much larger asteroid, estimated to be 4.5 billion years old, meaning it dates back to the earliest days of the solar system. At some point in its history, this asteroid may have contained saltwater, creating an environment where organic molecules could form and react. This supports the idea that water-rich asteroids could have delivered not just water but also organic compounds to Earth billions of years ago.
OSIRIS-REx: A Mission Years in the Making
NASA’s OSIRIS-REx spacecraft launched on September 8, 2016, reaching Bennu on December 3, 2018. The probe spent nearly two years mapping the asteroid, before collecting a sample on October 20, 2020. That sample, securely stored in a protective capsule, successfully landed back on Earth on September 24, 2023.
Since then, scientists have been meticulously analyzing the sample, looking for clues about the chemical and mineralogical history of the asteroid. The recent findings mark a significant step forward in understanding how life-friendly molecules could have spread across the cosmos.
What Does This Mean For The Search For Life?
The discovery of life’s building blocks in Bennu adds weight to the panspermia hypothesis, which suggests that life’s ingredients—or even life itself—could have been transported across space on asteroids and comets. While the findings don’t provide direct evidence of extraterrestrial life, they do indicate that the conditions necessary for life were not unique to Earth.
These results also raise exciting questions for future missions. With upcoming asteroid sample return missions, such as Japan’s MMX mission to Phobos (a moon of Mars) and NASA’s upcoming Dragonfly mission to Saturn’s moon Titan, scientists hope to find even more clues about the potential for life beyond Earth.
