NASA's OSIRIS-REx mission has discovered that the asteroid Bennu contains traces of ancient water, exotic salts and organic molecules, including amino acids and nucleobases - key components of DNA and RNA. These findings suggest that asteroids may have played a role in delivering the ingredients needed for life to Earth.
Bennu's mineral composition also indicates that it was once part of a water-rich parent body, challenging previous assumptions about the early solar system and the distribution of essential elements for life.
Bennu, a near-Earth asteroid, has long fascinated scientists because of its carbon-rich composition, which hints at its ancient past. When OSIRIS-REx returned 122 grams of material from the asteroid in 2023, researchers hoped for data about the early solar system. What they found exceeded expectations.
Analysis of Bennu's dust and pebbles revealed a sodium-rich brine, similar to the evaporated remains of lakes on Earth. These mineral deposits, known as evaporites, suggest that Bennu — or at least its parent body — once harbored liquid water. This strengthens the theory that asteroids were once wet worlds, capable of fostering complex organic chemistry.
Bennu's samples contained something even more surprising: amino acids, ammonia, and nucleobases—key components for life as we know it. These organic molecules form the basis of DNA and RNA, the blueprints of all living organisms. While similar compounds have been found in meteorites before, Bennu's pristine, uncontaminated nature confirms their extraterrestrial origin.
According to Yasuhito Sekine, an expert at the Institute of Science in Tokyo, the key to this discovery was the careful preservation of the samples. Unlike meteorites that fall to Earth and risk contamination, the Bennu samples were sealed in a controlled environment, ensuring their integrity.
Scientists believe these findings provide some of the strongest evidence yet that asteroids like Bennu may have seeded planets with the ingredients needed for life. Analysis of the sample revealed:
Sodium-rich minerals similar to those found in dried lake beds on Earth
Evaporites, which indicate the former presence of liquid water
Ammonia and nitrogen, essential for amino acids and organic synthesis
The five nucleobases necessary for the formation of DNA and RNA
Prebiotic chemistry, suggesting suitable conditions for the formation of life
If these compounds existed on Bennu, it's likely that they were widespread in the early solar system – meaning that the essential ingredients of life may have been common, rather than rare.
Bennu is believed to have once been part of a much larger asteroid that may have had underground lakes or even oceans. Over time, these liquid pockets evaporated, leaving behind salt deposits similar to those found in Earth's deserts.
Similar formations have been observed in:
Ceres, the largest body in the asteroid belt, which has bright salt deposits
Enceladus, Saturn's moon, known for its icy plumes and subsurface ocean
Europa, Jupiter's moon, where an ocean may lie beneath its thick shell of ice
The presence of these minerals on Bennu challenges previous assumptions about how and where water existed in the early solar system. If asteroids like Bennu carried both water and organic molecules, they could have acted as cosmic delivery systems, distributing the essential ingredients for life across planets and moons.
NASA isn't stopping with Bennu. Scientists are pushing for a sample return mission to Ceres, while China is planning its own asteroid mission. Meanwhile, on Mars, NASA has crucial samples waiting for a trip to Earth — but delays in the sample return mission mean scientists will have to focus on what Bennu has already discovered.
Some of the most exciting targets for future exploration include:
Ceres, where groundwater may still be present
Europa, an icy moon that could harbor life in its deep ocean
Enceladus, with its dramatic plumes of water erupting from the surface
Comets, which may carry even more organic material than asteroids
Could Bennu's ancient waters be a missing link to understanding how life began? Or could these findings hint at something even deeper—that the seeds of life are not unique to Earth? One thing is clear: our search for extraterrestrial life just got a lot more interesting.
(AA/BalkanWeb)
