Water, one of the essential ingredients for life on Earth, did not appear on the planet until after the moon-forming event.
A study led by Professor Katherine Bermingham of Rutgers University challenges what was previously thought about the origin of water on the planet, raising questions about how and when life on Earth truly began. The stage at which H2O arrived on the planet is what geologists refer to as the late accretion phase, when materials on Earth were finishing up the process of coming together to form something similar to what we have today.
Water and life on Earth
For life to emerge on a planet, three ingredients are needed: an energy source, the organic compound of elements known as CHNOPS (Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur, and more), and water. Without water, life cannot form, emphasizing the significance of this discovery.
“Determining when water arrived on our planet is one of the most important questions in planetary science,” said study lead Katherine Bermingham, a cosmochemist from the Department of Earth and Planetary Sciences at Rutgers University. “With this information, we can better pinpoint when and how life emerged on Earth.”
Bermingham’s job is to understand the chemicals that make up the solar system. She is particularly focused on the origins of the solar system and the planets and asteroids that form it. She does this by studying asteroid material and rocks on the Earth.
The research team used thermal ionization combined with an analytical method they developed for the study. Examining a particular molybdenum isotope, that is, a form of molybdenum with the same amount of protons naturally found in the element but a different number of neutrons, has given interesting results.
“The molybdenum isotopic composition of Earth rocks provides us with a special window into events occurring around the time of Earth’s final core formation when the last 10 percent to 20 percent of the material was being assembled by the planet. This period is thought to coincide with the Moon’s formation,” said Bermingham.
The scientists studied meteorites that landed in Greenland, South Africa, Canada, the United States and Japan. These specific meteorites, whose molybdenum originated from the moon-forming event, allows them to trace back to when H2O finally made it to the planet.
Researchers divide meteorites into two categories: CC and NC. CC meteorites are believed to have been created in the outer reaches of the solar system. NC meteorites are believed to have formed in the inner part of the solar system, which is drier because of proximity to the sun. The researchers found that the meteorites were NC types, meaning they did not bring any water to the planet.
“The data obtained support the idea that water arrived in small quantities after the formation of the Moon, during a much later stage of Earth’s evolution,” said Bermingham.
The finding suggests that water was introduced during the late accretion period of Earth’s formation, pushing the time frame of the dawn of life much sooner than scientists initially believed.