Moon collision made life possible on Earth, scientists say | Science & Tech News
The same interplanetary collision which created the moon also made life possible on Earth, according to new research.
Elements essential for life, likely including all of the carbon and nitrogen in our bodies, were introduced to our planet 4.4 billion years ago.
Petrologists – scientists studying the origin of rocks – believe Earth’s essential volatile elements were introduced in a collision with another planet which we later subsumed.
Rajdeep Dasgupta, the study’s co-author at Rice University in Texas, said: “From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted.
“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.”
Dr Gasgupta’s laboratory, which specialises in studying geochemical reactions deep within planets under intense heat and pressure, provided the evidence for the research.
The study’s lead author, graduate student Damanveer Grewal, gathered evidence to support the theory that Earth’s volatile elements arrived through a collision with an embryonic planet that had a core rich with sulfur.
The embryonic planet has to have had a sulphur-rich core because existing evidence about the chemical makeup of the Earth demands it.
Earth has many volatile elements, including carbon, nitrogen and sulphur, throughout its entirety – except in the core.
“The core doesn’t interact with the rest of Earth, but everything above it, the mantle, the crust, the hydrosphere and the atmosphere, are all connected,” Mr Grewal said. “Material cycles between them.”
By measuring the balance between the different volatiles within Earth’s crust, rather than its core, the team was able to establish what amount of sulphur would have been needed in the embryonic planet Earth collided with.
Dr Dasgupta is also the principal investigator on a NASA-funded research project called CLEVER Planets which is examining how essential elements could come together on distant planets.
He said that understanding the origin of these elements on Earth could have implications for life beyond the borders of our own solar system.
Dr 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.
“This removes some boundary conditions.
“It shows that life-essential volatiles can arrive at the surface layers of a planet, even if they were produced on planetary bodies that underwent core formation under very different conditions.”
The team at Rice University don’t believe that Earth’s bulk crust material – known as silicate – could have by itself maintained enough of the essential elements to produce our planet’s biosphere, atmosphere and hydrosphere.
“That means we can broaden our search for pathways that lead to volatile elements coming together on a planet to support life as we know it,” Dr Dasgupta added.