Scientists at Rice University believe that about 4.4 billion years ago, a cosmic body (most likely a very young planet the size of Mercury) crashed into Earth, and thanks to this, an important element for life - carbon - appeared on our planet. According to the researchers, if this event had not happened, then, most likely, life on our planet never appeared.
Geophysicists are struggling to find an answer to the question of how life could have formed on Earth. The fact is that if we take into account the environmental conditions of the early Earth, then the carbon available on the planet, most likely, should have simply burned out, not later becoming the key to the emergence of life. After conducting an experiment using high pressure and temperatures, scientists came to the conclusion that almost all of the carbon contained at that time (about 4.4 billion years), most likely appeared on the planet as a result of its collision with another planetary body.
Nevertheless, scientists could not find an answer to the question of how such volatile elements as hydrogen, carbon, nitrogen and sulfur were able to remain trapped in the mantle of our planet. Computer models showed that most of the volume of carbon had to evaporate into space, or else go to the metal core of our planet, being attracted by its rich iron alloys.
Before the new study, many scientists believed that volatile elements appeared on our planet after the formation of its core was completed. However, geophysicists at Rice University and study co-author Yuan Li have a slightly different opinion:
“None of these elements, which hit the Earth with the same meteorites and comets more than 100 million years after the formation of the solar system, could have stayed on the planet due to the fact that the Earth at that time looked like one continuous ocean from hot lava. In addition, there is still no reliable evidence that meteorites and comets can contain sufficient amounts of these volatile elements."
Lee and his colleagues began their research about three years ago. Scientists conducted a series of experiments in which they tried to find out how much the ratio of carbon to iron would change if they were influenced by other elements contained in the early Earth. Scientists conducted their studies taking into account interference from other space objects with a characteristic different chemical composition.
“We decided that it was time to stop researching the usual composition of iron, nickel and carbon. Therefore, they began to study compositions rich in sulfur and silicon alloys. Part of the interest was fueled by the fact that the core of Mars is supposedly rich in sulfur and the core of Mercury is rich in silicon,”said study co-author Rajdip Dagupta.
If the theory is correct, the collision was so powerful that the Earth actually engulfed the protoplanet.
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In their laboratory experiments, scientists tried to replicate the high-pressure and high-temperature conditions that are characteristic of the center of the Earth and other rocky planets. The results showed that carbon could have "flowed" from the core of a planet that collided with Earth into our planet's mantle, along with silicon and sulfur.
“The planet's core, as well as its carbon-rich mantle, has virtually merged with the core and mantle of our proto-Earth,” says Dagupta.
According to scientists, this collision most likely happened about 4.4 billion years ago, about 150-200 million years after the formation of the Earth. Since carbon remained trapped under the crust of our planet, whose environmental conditions became milder over time, life appeared over time. Most scientists agree that microbial life appeared on Earth about 4.1 billion years ago.
It is important to take into account that the variant of the collision of the ancient Earth with a protoplanet requires taking into account several random and not very circumstances at once. Scientists agree that much more research is needed to support this theory, including analysis of common elements other than carbon. If the theory is ultimately confirmed, it will become clear that the Earth became an oasis of life only thanks to a catastrophic planetary collision.
NIKOLAY KHIZHNYAK