Imagine if the ingredients for life didn’t start on Earth but instead came from space. Sounds like something out of a sci-fi movie, right? Well, recent discoveries from NASA’s study of asteroid Bennu suggest that this might be true. Scientists have found key organic molecules, such as amino acids and DNA components, inside samples taken from the asteroid, providing strong evidence that space rocks like Bennu could have delivered the building blocks of life to our planet billions of years ago.
NASA’s OSIRIS-REx mission collected dust and rock samples from Bennu in 2020, and when the capsule landed back on Earth in September 2023, researchers were stunned to find even more material than expected. These samples have remained untouched by Earth’s environment, making them the purest extraterrestrial material scientists have ever studied. Now, researchers are uncovering incredible details about what may have happened in the early solar system.
The Ingredients for Life are Older than Earth
Asteroid Bennu is not just an ordinary space rock—it is a carbon-rich asteroid. This means it contains materials that are essential for life. When scientists analysed the samples, they found water, carbon, nitrogen and a variety of organic molecules, including 33 different amino acids. Amino acids are crucial because they help form proteins, which are the building blocks of life as we know it.
Even more exciting, the team detected all five nucleobases that makeup DNA and RNA: adenine, guanine, cytosine, thymine and uracil. These molecules carry genetic instructions for life on Earth. In simple terms, this indicates that the basic materials needed to create life might have existed in space long before Earth was formed.
Bennu’s samples also contained important minerals and salts, including some that had never been seen in asteroid samples before. Scientists believe these materials were once part of a much larger asteroid that formed about 4.5 billion years ago, possibly far from the Sun, where icy conditions allowed complex organic molecules to develop.
Did an Asteroid Deliver Life to Earth?
This discovery strengthens a long-standing scientific theory: asteroids and comets bombarded the early Earth, bringing water and organic materials that helped life begin. If this happened here, could it have happened on other planets too?
One puzzling question remains. If Bennu had all the right ingredients for life, why didn’t life form there? Scientists think it may be because the right environmental conditions, like stable water and warmth, were missing. However, the presence of water-rich minerals suggests that liquid water once existed inside Bennu’s parent asteroid. This means that chemical reactions could have taken place, helping to form the complex molecules needed for life.
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Another surprising detail is that the amino acids in Bennu’s samples exist in two “mirror-image” versions, like left and right hands. On Earth, life only uses left-handed amino acids, but Bennu’s samples contain an equal mix of both. This suggests that before life began, both forms of amino acids were present, and something later caused Earth’s life forms to favour only the left-handed ones. Scientists are still trying to figure out why this happened.
These findings open up new questions about how life began—not just on Earth but possibly elsewhere in the universe. If space rocks like Bennu delivered the materials for life to our planet, could the same thing have happened on Mars, Europa (Jupiter’s moon), or Titan (Saturn’s moon)? Scientists plan to keep studying the Bennu samples to learn more about how these organic compounds formed and changed over time.
One thing is clear: the story of life on Earth may have started long before our planet even existed, written in the dust and rocks of ancient asteroids. As we continue exploring space, who knows what other secrets we’ll uncover?
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