Scientists examining a sample obtained from the asteroid **Bennu** have discovered amino acids and intricate mineral compounds, some of which have not been detected in space rocks previously. The observations, facilitated by NASA’s OSIRIS-REx mission, provide fresh insight into the chemical foundations of life and the initial conditions of the solar system.
### Ancient Brine and Complex Minerals
Investigators at the Smithsonian’s National Museum of Natural History uncovered a saline residue in the Bennu sample, a remnant of an ancient brine. As this brine evaporated, it left behind minerals abundant in sodium, carbon, sulfur, phosphorus, chlorine, and fluorine. These discoveries imply that the conditions required to create such compounds were more prevalent in the early solar system than earlier thought.
### Amino Acids: Building Blocks of Life
In a distinct study conducted by NASA researchers, various types of amino acids—the crucial components of proteins—were identified in the asteroid material. Among these were 14 out of the 20 amino acids utilized by life on Earth for protein synthesis. Significantly, these identical amino acids have also been discovered in meteorites, further reinforcing the notion that space rocks may have brought the chemical precursors for life to Earth.
### The Origins of Life on Earth
This new research supports the hypothesis that collisions with water-rich asteroids delivered pivotal chemicals, including water and prebiotic organics, to Earth and other celestial bodies in the solar system. Tim McCoy, a primary author of the Smithsonian study, stated, “If water-rich asteroids were routinely generating these elements, and we know that asteroids impacted the surfaces of planets and moons early in their evolution, these primordial asteroids undoubtedly contributed both water and prebiotic organics to Earth, Mars, and other planets and moons.”
The findings were shared in two individual articles in *Nature* and *Nature Astronomy*.
—
### OSIRIS-REx: A Historic Mission
NASA’s OSIRIS-REx mission, which stands for **Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer**, was launched in 2016 with the objective of gathering a sample from Bennu. Following a 4-billion-mile voyage, the spacecraft successfully delivered the sample capsule onto a Utah desert in September 2023. This event marked the first U.S. mission to return a sample from an asteroid and the most significant retrieval of extraterrestrial material since the Apollo moon missions (1969–1972).
The mission returned approximately half a cup of crushed Bennu rocks and soil, which scientists are now scrutinizing. Initial findings have already surpassed expectations, providing a wealth of information regarding the chemical origins of life.
—
### Traces of Water and Soda Ash
One of the most unexpected revelations in the Bennu sample was the detection of water-bearing sodium carbonate compounds, commonly referred to as soda ash. These compounds, which naturally develop in dry lake beds on Earth, had never been identified in asteroids or meteorites before. The brine that resulted in these minerals was also abundant in phosphorus, a vital element for life as it constitutes the backbone of DNA.
Phosphorus is relatively scarce compared to other essential biological elements like hydrogen, carbon, nitrogen, oxygen, and sulfur. Scientists speculate that similar brines might still be present on distant worlds, such as Saturn’s icy moon **Enceladus**, where spacecraft have recognized sodium carbonate.
“From a biological standpoint, phosphate is one of the critical building blocks – alongside sugar – of the single and double helix that constitute RNA and DNA,” McCoy elaborated. “Without a phosphate-rich system, these intricate molecules that compose living organisms simply could not have formed.”
—
### Bennu’s Ancient Origins
Some of the mineral fragments in the Bennu sample may predate the solar system itself, making them older than 4.6 billion years. These grains of stardust may have originated from dying stars or supernovas that ultimately contributed to the formation of the Sun and planets.
The researchers also found indications that Bennu might have originated from a larger icy body, such as the dwarf planet **Ceres**. The asteroid’s composition includes ammonium and carbonate salts, along with organic carbon, suggesting that liquid water may have flowed through it, even under extremely cold conditions. These findings imply that chemical processes necessary for life could have persisted long after the asteroid’s internal heat faded.
—
### A Blueprint for Life Beyond Earth
The NASA-led study also discovered five nucleobases — the molecules that form the foundation of RNA and DNA — alongside the amino acids. This finding enhances the theory that asteroids like Bennu may have been instrumental in providing the components essential for life to Earth.
The paper indicates that the minerals in Bennu’s rocks formed in stages as water transported dissolved substances. These phases encompassed the formation of calcium and magnesium carbonates, phosphates, sodium carbonates, and salts such as table salt and sulfates. High concentrations of ammonium salts in the