Key elements for life came from inner solar system, study finds

Life on Earth may owe its existence not to cosmic debris from the outer solar system, as long believed, but to materials originating closer to the sun. New research suggests that two of the six essential elements for life – nitrogen and phosphorus – were delivered to Earth from the inner solar system.

These elements are critical building blocks: nitrogen is fundamental for proteins, while phosphorus is vital for DNA and energy transfer molecules (ATP). They are considered the "finishing touches" that imbue life with vitality, akin to brushstrokes completing a painting, while carbon, hydrogen, and oxygen form the basic sketch.

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This study suggests that Earth obtained the life-essential elements of phosphorus and nitrogen primarily from the inner solar system, not the outer regions as previously thought.

Researchers at Rice University analyzed the phosphorus-to-nitrogen (P/N) ratios in primitive meteorites. Their findings indicate that while early solar system turbulence initially pushed phosphorus-rich particles outward, the formation of Jupiter created a gravitational barrier. This barrier altered the distribution, leading to a higher P/N ratio in meteorites formed closer to the sun (inner solar system) compared to those from further out.

"The change in the direction of elemental ratios between the two generations of planetesimals was the opposite, but there was one commonality: in both generations, the P/N ratio of planetesimals formed in the inner solar system was most similar to the ratio on present-day Earth," stated the study published in Science Advances. This implies that Earth was largely self-sufficient in acquiring nitrogen and phosphorus, supplementing these with other essential elements delivered by asteroids from the outer solar system.

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In our solar system, Jupiter played a very important role in determining the distribution of the basic chemical ingredients needed to form a habitable planet.