NASA scientists have recreated the conditions which could have given birth to life itself at the bottom of the ocean four billion years ago.
NASA scientists are learning to recognise life on other planets by studying the origins of life on Earth.
Specifically, how the ingredients for human existence could have formed on the ocean floor 4 billion years ago. Their experiment could help unlock answers to how life on earth was formed and provide clues on how to look for it on the cosmos.
Astrobiologist Laurie Barge and her team at NASA's Jet Propulsion Laboratory in Pasadena, California, are working to better identify life on other planets by studying the origins of life here on Earth. Their research focuses on how the building blocks of life form in hydrothermal vents on the ocean floor.
Laurie Barge, left, and Erika Flores, right, in JPL's Origins and Habitability Lab in Pasadena, California. Credit: NASA/JPL-Caltech
To recreate these vents, the team made their own miniature sea floors by filling beakers with mixtures that mimicked the chemical composition of the ancient ocean. These lab-based seafloors act as nurseries for amino acids, organic compounds essential for life as we know it.
Found around cracks in the deep ocean, hydrothermal vents are where natural chimneys develop, releasing fluid that’s been heating below Earth’s surface. When that solution interacts with seawater, it creates a sort of unrest, an environment in constant flux.
It’s this dark, warm environment that may be the key to understanding how life forms on foreign planets, far from the heat of the Sun, are born.
As the lead investigator and the first author on the new study, which published in the journal Proceedings of the National Academy of Sciences, Dr Barge said the research was certainly aimed at looking for life elsewhere.
“Understanding how far you can go with just organics and minerals before you have an actual cell is really important for understanding what types of environments life could emerge from,” Barge said in a statement.
"Also, investigating how things like the atmosphere, the ocean and the minerals in the vents all impact this can help you understand how likely this is to have occurred on another planet."
Barge and Flores used ingredients commonly found in early Earth's ocean in their experiments. They combined water, minerals and the "precursor" molecules pyruvate and ammonia, which are needed to start the formation of amino acids. They tested their hypothesis by heating the solution to 158 degrees Fahrenheit (70 degrees Celsius) — the same temperature found near a hydrothermal vent — and adjusting the pH to mimic the alkaline environment. They also removed the oxygen from the mixture because, unlike today, early Earth had very little oxygen in its ocean. The team additionally used the mineral iron hydroxide, or "green rust," which was abundant on early Earth.
The green rust reacted with small amounts of oxygen that the team injected into the solution, producing the amino acid alanine and the alpha hydroxy acid lactate. Alpha hydroxy acids are byproducts of amino acid reactions, but some scientists theorize they too could combine to form more complex organic molecules that could lead to life.
They found that the conditions similar to early Earth's and potentially those of other planets, it is possibly to form amino acids and alpha hydroxy acids from a simple reaction in mild conditions.
Jupiter’s ice-covered moon Europa could harbour life
The group will continue to study these reactions, in hopes of finding more ingredients for life and creating more complex molecules.
“We don’t have concrete evidence of life elsewhere yet,” Barge said. “But understanding the conditions that are required for life’s origin can help narrow down the places that we think life could exist.
In a study published in Scientific Reports, researchers focused on how Europa’s subsurface ocean would have a potentially life-giving cocktail of liquid water and gravity-generated heat emanating from its core. The paper draws some very interesting parallels between Europa and certain places here on Earth where the recipe for life is ideal for bacteria to thrive without the presence of sunlight such as around 'black smokers' on the ocean floor.
The study follows another in which researchers observed a single-celled organism evolve into a multi-celled one in a laboratory, recreating one of the most important leaps in evolutionary history.
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