الخميس، 2 مارس 2023

How NASA Scientists Study the Origin of Life By Simulating Primordial Earth

Today, life and the byproducts thereof inhabit every nook and cranny of Earth, but there was a time when nothing lived on our home planet. Researchers from NASA’s Jet Propulsion Laboratory (JPL) studying the origins of life successfully simulated an important pre-biotic chemical reaction last year. JPL is talking about the work that went into that research and how we might study the origins of life in the future.

In 2022, researchers from JPL’s Origins and Habitability Lab confirmed they had simulated an important metabolic reaction in a closed environment intended to resemble the conditions on primordial Earth. This reaction, the chemical reduction of a molecule called NAD+ with iron sulfide minerals, shows how the processes we associate with life can arise from a non-living geochemical system. But this is just one small piece of the puzzle, and it was no simple feat to do.

Life permeates every part of JPL’s laboratories. NASA accidentally demonstrated that when it tried to produce ultra-clean sample tubes for Perseverance, only to find that removing all hydrocarbon evidence of life changes the way metal components fit together. To simulate Earth 4 billion years ago, researchers have to create small isolated pockets of primordial atmosphere. That means no oxygen, which is a fundamental component of most life today. But Earth had negligible oxygen in its atmosphere before the appearance of life.

The Origins and Habitability Lab uses a “glove box” about the size of your average vending machine (see above) to create such an environment. The interior is sealed to keep oxygen out — researchers need to use a small airlock to add and remove items. Using the built-in gloves, scientists can run experiments protected from Earth’s atmosphere. However, all the instruments used to evaluate the results also need to fit inside the box, and there’s only room for one person to work at a time.

This illustration of early Earth includes liquid water as well as magma seeping from the planet’s core due to a large impact. Credit: Simone Marchi

It took months for the team to demonstrate the NAD+ reaction in the lab, but as JPL research scientist Laurie Barge says, “science is all about repetition.” The team is currently examining more parts of the metabolic process in this environment, hoping to find a step somewhere in the mix that can only occur inside a protective membrane. We know that simple lipid membranes can self-assemble, and understanding which metabolic process require that sort of environment can help scientists nail down when membranes first developed.

Astrobiology researchers at JPL look forward to a time when we have a better understanding of nearby planets and moons. It’s possible that a lifeless world could have similar conditions as a young Earth, making it an ideal place to test hypotheses about the origins of life on a scale far beyond a glove box. Not only would this help explain the origins of life on Earth, but it could also show scientists what to expect when hunting for life on other planets.

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