Origin of Life? Planetary 'Smash Up' With Mercury-Like Planet May Have Started Life on Earh

Carbon gave life to the planet, but the question is where did this carbon come from? Scientists from Rice University have a possible answer: a planetary collision 4.4 billion years ago.

According to a report from Phys Org, a new study published in Nature Geoscience said that a crash between Earth and an embryonic planet similar to Mercury could have brought carbon to the planet. After all, existing carbon in Earth back then should have boiled or been trapped in the core instead of being present in the mantle and biosphere to propagate life.

"The challenge is to explain the origin of the volatile elements like carbon that remain outside the core in the mantle portion of our planet," petrologist Rajdeep Dasgupta explained. "Even before this paper, we had published several studies that showed that even if carbon did not vaporize into space when the planet was largely molten, it would end up in the metallic core of our planet, because the iron-rich alloys there have a strong affinity for carbon."

Dasgupta is co-author of the study along with lead author and Rice postdoctoral researcher Yuan Li, Rice research scientist Kyusei Tsuno and Woods Hole Oceanographic Institute colleagues Brian Monteleone and Nobumichi Shimizu.

The team conducted unconventional experiments to try and solve the conundrum, eventually discovering that it's possible for carbon to be excluded from the core if the iron alloys there contain high amounts of silicon or sulfur.

"One scenario that explains the carbon-to-sulfur ratio and carbon abundance is that an embryonic planet like Mercury, which had already formed a silicon-rich core, collided with and was absorbed by Earth," Dasgupta said. "Because it's a massive body, the dynamics could work in a way that the core of that planet would go directly to the core of our planet, and the carbon-rich mantle would mix with Earth's mantle."