Recent research published in the journal Geochimica et Cosmochimica Acta reveals that water reached Earth during the late stages of the planet's evolution from dust and gas, specifically during late accretion when the planet was gathering the last 10 to 20% of its material. The study, led by scientists from Rutgers University-New Brunswick, challenges previous theories that the Moon-forming event was the primary mechanism for delivering water to Earth.
A team of researchers, headed by Katherine Bermingham, a cosmogeochemist specializing in the chemical composition of materials in the solar system and an associate professor in the Department of Earth and Planetary Sciences at Rutgers University-New Brunswick, concluded that water did not arrive as early during Earth's formation as previously believed.
The scientists studied molybdenum isotopes, an element that can provide clues about events that occurred when Earth's core formed. They extracted molybdenum samples from meteorites stored at the National Museum of Natural History at the Smithsonian Institution to track Earth's early chemical history. By comparing the isotopic compositions of these meteorites with rocks from Greenland, South Africa, Canada, the US, and Japan, they aimed to determine whether the Moon-forming event delivered water to Earth.
"Our research results show that the Moon-forming event was not the main cause of the arrival of water on Earth, unlike previous theories," Bermingham said, according to Universe Today. The analysis showed that Earth's rocks are more similar to meteorites from the inner solar system, known as NC-type, which are considered drier, than to meteorites from the outer solar system, or CC-type, where water and other volatiles were more abundant.
Once the different samples were gathered and their isotopic compositions measured, the team compared the meteorites' signatures with the rock signatures to see if there was a similarity or a difference. "And from there, we drew inferences," Bermingham explained. "We have to figure out from where in our solar system Earth's building blocks—the dust and the gas—came and around when that happened. That's the information needed to understand when the stage was set for life to begin."
According to scientists, at least three main elements are needed for life to emerge: water, energy, and a mixture of organic chemical elements known as CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur). Understanding when and how water arrived on Earth is crucial for piecing together the story of life's origins, as noted by Universe Today.
The data supports the idea that water arrived in small quantities after the formation of the Moon, during the late stages of Earth's formation. "This discovery changes the understanding of when conditions for life could have originated on our planet," the researchers stated, implying that the necessary conditions for life may have been established during a different period than previously thought.
This finding has implications for understanding the origin of life, suggesting that water must have arrived in smaller portions later through a combination of asteroid impacts and other processes. "When water was delivered to the planet is a major unanswered question in planetary science. If we know the answer, we can better constrain when and how life developed," Bermingham said, as reported by Earth.com.
The article was written with the assistance of a news analysis system.