Moon-Forming Collision Left Key Elements on Earth, Study Finds

Rice University petrologists have found Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from the planetary collision that created the moon more than 4.4 billion years ago. (Image courtesy of Rice University)

(CN) – Scientists at Rice University say elements essential for the formation of life were left on Earth after a planet the size of Mars crashed into it over 4.4 billion years ago and created the moon.

A new study published Wednesday in the journal Science Advances claims it is likely that nitrogen and carbon – two of only six elements that make up most of the human body – were left on Earth from the theorized moon-forming cosmic collision.

A team of five researchers from the Rice University Department of Earth, Environmental and Planetary Sciences wanted to explore whether elements that make up the building blocks of life on Earth came from collisions with meteorites or some other way.

After computing a billion different cosmic scenarios and comparing the results with current solar system conditions, they concluded a planet with a core high in sulfur would also contain carbon and nitrogen on its surface, which could transfer to Earth after a collision.

The research also suggests a rocky planet like Earth might gain more key “volatile” elements if it is able to grow following sizeable impacts with planets that have certain elements.

“From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted,” study co-author Rajdeep Dasgupta said in a statement. “But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all of the geochemical evidence.”

Dasgupta added, “This study suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have sampled different building blocks, perhaps from different parts of a protoplanetary disk,” 

The study’s lead author, Rice graduate student Damanveer Grewal, set up a series of experiments simulating high pressures and temperatures during a planet’s core formation and found that a sulfur-rich core would mean large amounts of carbon and nitrogen on a planet’s surface.

“What we found is that all the evidence — isotopic signatures, the carbon-nitrogen ratio and the overall amounts of carbon, nitrogen and sulfur in the bulk silicate Earth — are consistent with a moon-forming impact involving a volatile-bearing, Mars-sized planet with a sulfur-rich core,” Grewal said.

In addition to Grewal and Dasgupta, study authors include Cenguang Sun, Kyusei Tsuno and Gelu Costin.

Another recent study found that nearly three times more asteroids have collided with the Earth and moon in the past 290 million years than ever before.

These findings have implications for the history of life on Earth, particularly as asteroid strikes have had a significant role in mass extinction events and the rapid evolution of species that follows.

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