Collision with Mars-like planet may have spawned life on Earth

Amazing new research suggests that a collision between two planets likely resulted in the birth of life on Earth.

All of the creatures that surround us – both visible and invisible – may only be here thanks to a violent collision in our solar system billions of years ago.

New research published to Science Advances by a team from Rice University has found evidence that the vast bulk of many of the chemical elements essential for life – such as carbon, nitrogen and certain volatile elements – were left on Earth after it collided with another planetary object.

This event, believed to have resulted in the creation of the moon, occurred more than 4.4bn years ago. Astronomers have been wondering, though, why the Earth and other rocky planets in the inner solar system are noticeably volatile-depleted.

This latest scenario put forward by the researchers is the first to explain the timing and delivery of these volatile elements in a way that is consistent with all of the geochemical evidence.

In a series of experiments, the researchers tested a longstanding theory that Earth’s volatiles arrived following the collision of this long-lost planet, which had a sulphur-rich core. This sulphuric content would be key to the seeding of elements on Earth, and it could explain why elements such as carbon, nitrogen and sulphur are found all over our planet, except for its core.

1bn computer simulations

One such theory put forward to explain where Earth’s volatiles came from, called the ‘late veneer’ theory, suggests that volatile-rich meteorites from the outer solar system reached Earth after its core had formed. However, using high-temperature, high-pressure experiments that replicate what’s going on inside our planet, it was shown that the elemental ratio of carbon to nitrogen was off.

Eventually determining the known ratios and concentrations of elements both on Earth and in non-terrestrial bodies, the researchers designed a computer simulation to find the most likely scenario that produced Earth’s volatiles. After running approximately 1bn simulations, the team found the most likely answer.

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

His colleague, Rajdeep Dasgupta, who explores how life-essential elements form on distant, rocky planets, 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 disc.”

“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.”