New Research Challenges Comet Theory of Life's Origin on Earth

A new study suggests that the popular scientific theory that comets played a significant role in initiating life on Earth billions of years ago may be incorrect

A new study suggests that the popular scientific theory that comets played a significant role in initiating life on Earth billions of years ago may be incorrect.

This theory, which has been prevalent for decades, has been challenged by new computer simulations.

According to the new research, essential organic molecules necessary for life found in comets were likely destroyed upon impact with Earth. This finding necessitates a re-evaluation of a long-held belief about the origin of life, established at least since 1961.

The widespread concept that the fundamental elements of life arrived on Earth from space is called 'Panspermia'. This concept was scientifically presented as early as 1908.

Complex organic molecules are required for life to develop on Earth. However, it is still unclear whether sufficient raw materials were available on early Earth to form the chemical structures that form the basis of life. The chemical reactions that form the basic structures of life are called 'prebiotic chemistry'.

Comets are mainly composed of dust and ice, but they also contain organic matter. Due to this composition, comets are even called 'dirty snowballs'. Based on this, scientists had speculated that comets might have delivered water and organic molecules to Earth's surface.

However, a new study published in the scientific journal Scientific Reports on Wednesday has questioned this belief. According to the study, it is estimated that more than one hundred thousand comets larger than 100 meters may have impacted Earth more than four billion years ago. But the impact of most of these was so powerful that the molecules necessary for the origin of life could not survive.

According to Richard Anslow, the lead researcher who conducted this research as part of his doctoral studies at the Institute of Astronomy at the University of Cambridge, UK, his team performed one hundred thousand computer simulations of early Earth conditions using the latest scientific models of comet formation and evolution.

'Based on what we know about the conditions on the surface of early Earth, on average, no comet impact was successful,' Anslow said. According to him, even though comets contained essential molecules for life in sufficient quantities, they arrived on Earth at very high speeds, making the possibility of their safe arrival very low.

'The normal speed of comets upon impact with Earth is very high, so the possibility of them delivering intact organic molecules is extremely low. Therefore, comets may not be as useful for prebiotic chemistry as previously thought,' he said.

According to the study, 54 percent of the simulations did not result in a comet impact. The remaining 46 percent showed at least one impact. Among these, very few simulations showed up to three impacts.

However, Anslow states that the possibility of organic molecules necessary for life reaching Earth safely from comet impacts cannot be completely ruled out. But for that, a comet would have had to fall in a very specific location on Earth where liquid water and other necessary chemicals for life were already present. He says the probability of such a coincidence is very low.

Alternative Theories

The new study primarily analyzed a natural chemical called hydrogen cyanide (HCN), considered important for prebiotic chemistry. This chemical has been found in dozens of comets, including Halley and Hale-Bopp. HCN, composed of hydrogen, carbon, and nitrogen, can help form amino acids when it reacts with water. Amino acids are the basic molecules that build proteins. Previous studies have also identified HCN as an important chemical element for the origin of life on Earth.

However, when comets impact Earth, extreme temperatures and pressures are generated. According to Anslow, recent studies have shown that these high temperatures and pressures can destroy the basic chemical molecules of life.

According to the authors of the new study, even if comets impacted successfully, the possibility of a sufficient amount of useful chemicals reaching Earth from them is low. If a comet falls into the ocean, there is also a possibility that such chemicals will dissolve quickly in the water.

Furthermore, other chemical compounds containing elements like phosphorus and sulfur are also necessary for prebiotic chemistry. However, such substances are not regularly found in comets.

According to Anslow, comets could have delivered hydrogen cyanide, but since it was not certain where on Earth the comet would fall, there was no guarantee that all the necessary chemical elements for life formation would be available in one place.

If comets did not bring the basic elements of life to Earth, researchers suggest looking for other potential sources of their origin.

One old theory suggests that the molecules necessary for life may have formed from the chemical mixture present on early Earth, known as the 'primordial soup'.

Another potential source could be asteroids. Compared to c