According to a recent study published in the journal Life, the initial components of life on Earth could have emerged as a result of solar eruptions. The study reveals that when solar particles interacted with gases in the planet’s primitive atmosphere, amino acids and carboxylic acids were formed. These substances are the fundamental building blocks of organic life and proteins, as evidenced by a sequence of chemical experiments.
Many scientists have been investigating the origins of life by examining how amino acids, the building blocks of proteins and all cellular life, came to exist. One theory, dating back to the late 1800s, suggests that life might have emerged in a concentrated mix of chemicals in a “warm little pond” that was energized by lightning and heat.
To test this theory, Stanley Miller from the University of Chicago tried to recreate these primordial conditions in 1953. He used a closed chamber filled with gases thought to have been prevalent in Earth’s early atmosphere, including methane, ammonia, water, and molecular hydrogen. By repeatedly igniting an electrical spark to simulate lightning, Miller created 20 different amino acids within a week.
However, recent research has complicated this interpretation. Scientists now believe that Earth’s early atmosphere contained more carbon dioxide and molecular nitrogen than methane and ammonia. These gases require more energy to break down and can produce amino acids but in much smaller quantities.
To explore alternative energy sources, some researchers have suggested shockwaves from incoming meteors or solar ultraviolet radiation. Vladimir Airapetian, a co-author of a new paper and a stellar astrophysicist at NASA’s Goddard Space Flight Center, has proposed a new idea based on data from NASA’s Kepler mission. Airapetian’s study suggests that during the first 100 million years of Earth’s existence, the Sun was about 30% dimmer than it is now, but it had more frequent solar “superflares.” These powerful eruptions launched near-light speed particles that regularly collided with Earth’s atmosphere, initiating chemical reactions that led to the creation of organic molecules.
Upon publishing his paper on the potential role of solar particles in the formation of early Earth’s organic molecules, Vladimir Airapetian received contact from the Yokohama National University team in Japan. Professor of Chemistry, Dr. Kobayashi, who had studied prebiotic chemistry for the past 30 years, was interested in investigating the effects of galactic cosmic rays on the early Earth’s atmosphere. Minor modifications to Kobayashi’s existing experimental setup allowed for the testing of Airapetian’s ideas, using a gas mixture containing carbon dioxide, molecular nitrogen, water, and a variable amount of methane to simulate Earth’s early atmosphere. The team found that, with a methane proportion of over 0.5%, the gas mixture shot by protons produced detectable amounts of amino acids and carboxylic acids, whereas spark discharges required a 15% methane concentration before any amino acids formed. Additionally, the production rate of amino acids by spark discharges was a million times less than that by protons, and protons also produced more carboxylic acids than spark discharges.
According to Airapetian, the efficiency of solar particles as an energy source appears to be higher than that of lightning, assuming all other factors are equal. However, the conditions on early Earth were different from those today, and lightning would have been less common under a 30% dimmer Sun. As a result, solar particles are now considered a more likely source for the precursors of life. These experiments indicate that our active young Sun may have played a more significant role in catalyzing the building blocks of life than previously thought, and may have done so earlier than expected.
