In October 2020, NASA’s OSIRIS-REx spacecraft collected a sample from the near-Earth asteroid Bennu. Now, the 120-gram sample of asteroid dust has been chemically analyzed, and the findings shed light on Bennu’s composition and the possible biochemical route that built life from scratch on our planet.
Researchers have detected the presence of organic compounds and minerals that serve as building blocks of life. The new findings fuel the idea that asteroids delivered the building blocks of life to our planet, establishing the basis of life on our planet. The samples also open avenues for understanding the chemical and biological processes that might have occurred when the asteroid moved erratically during the solar system’s early days.
Preliminary research revealed the presence of nitrogen, carbon, and water— all key to the formation of molecules that are essential to the presence of life. The latest research, on the other hand, focuses on the composition of organic material found in the asteroid sample. As Dr. Daniel P. Glavin, senior scientist for samples return at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, suggests, new research has shown the presence of amino acids and nucleic acids found in DNA. He further states that these discoveries are exciting as they suggest that asteroids like Bennu could have acted like chemical factories in space and might have been a source of raw ingredients for the formation of life on Earth and possibly other bodies of the solar system. Apart from Glavin’s research, a separate team has worked with the sample and has uncovered the presence of salts and minerals crucial to life. They have also highlighted the role of ancient water on the asteroid.
Glavin and his team detected 33 amino acids, 14 of which are used in biology to build proteins and 19 non-protein amino acids. The team also found all five nucleobases—adenine, guanine, cytosine, thymine, and uracil—essential components of DNA and RNA. These compounds have been found in meteorites before, but they have been exposed to heating during atmospheric entry and contaminants on the surface of Earth. However, the sample taken from Bennu has been recovered without external exposure as the rare cache has been sealed from contaminants and atmospheric heating. According to Glavin, these results provide a convincing argument that building blocks of life could have originated on alien bodies and are not just contaminants from Earth.
Glavin also found compounds rich in nitrogen and ammonia, which indicates that Bennu was part of a larger asteroid formed 4.5 billion years ago in frigid regions of the solar system. Glavin also found ammonia ice on this unique asteroid. Ammonia ice becomes unstable when close to the sun. According to the researchers, ammonia ice melted to form pockets of liquid inside the rock, forming complex organic molecules such as amino acids and nucleobases.
McCoy’s team found salt and minerals in the sample taken from Bennu. They were surprised to find the mineral trona, or sodium carbonate, which had not been observed directly in asteroids and meteorites before. The researchers have provided insights into this observation. According to them, water flowed in pockets and veins in the parent asteroid, which was a big pile of mud in the early days of the solar system. Cracks and fractures in the asteroid provided openings into the surface. The water evaporated and reached the surface, leaving behind a ‘soup’ of elements. Brines like these can also support the environment needed to form life.
The presence of water, minerals, and amino acids suggests that these building blocks interacted with one another in interesting ways but never achieved the final fruit— life. However, the findings suggest that building blocks of life on Earth might have come from asteroid collisions. As for further research, Glavin believes that future missions in our solar system will unearth more information on how life began on Earth.
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