Before life emerged on Earth, basic chemistry was needed to create organic molecules from the basic building blocks of nitrogen, sulfur, carbon and phosphorus. These elements had to be present in large quantities and constantly replenished in order for proper chemical reactions to begin and be sustained. However, there was and still is a deficiency of these elements on Earth.

In fact, the basic building blocks of life were so rare that even if chemical reactions began, they would quickly be exhausted. Geological processes such as weathering and weathering of the rocks that form the Earth also failed to provide sufficient resources because the Earth’s crust contained so few of these elements. But over the first 500 million years of Earth’s history, prebiotic chemistry evolved to produce organic molecules such as RNA, DNA, fatty acids, and proteins that form the basis of all life.

Materials from outer space?

Where did the required amounts of sulfur, phosphorus, nitrogen and carbon come from? Geologist and Nomis employee Craig Walton believes that these elements came to Earth mostly as cosmic dust.

This dust is formed in space, for example, as asteroids collide with each other. Even today, approximately 30,000 tons of dust fall from space to Earth every year. However, in the early days of the Earth’s existence, dust fell in much larger volumes, reaching millions of tons per year. But above all, dust particles contain plenty of nitrogen, carbon, sulfur and phosphorus. They will therefore have the potential to trigger a chemical cascade.

However, the fact that the dust is dispersed over a wide area and can only be found in very small quantities in one place suggests otherwise. “But when you include transportation processes, things look different,” says Walton. Wind, rain or rivers collect cosmic dust over a wide area and accumulate it in concentrated form in certain places.

A new model to clarify the question

To find out whether cosmic dust is the source that triggers prebiotic chemistry (reactions), Walton and colleagues from the University of Cambridge developed a model. Using the model, the researchers simulated how much cosmic dust fell on Earth during the first 500 million years of our planet’s history and where it might have accumulated on the Earth’s surface. Their research was published in a scientific journal Nature Astronomy.

The model was developed in collaboration with sedimentation experts and astrophysicists from the University of Cambridge. British researchers specialize in modeling planetary and asteroid systems.

Their simulations show that the early Earth could have had places with extremely high concentrations of cosmic dust. And these materials were constantly replenished from space. However, after the formation of the Earth, the amount of dust showers decreased quickly and sharply: after 500 million years, the dust shower was much smaller than in year zero. Researchers explain accidental rise of asteroids that broke apart and sent a dust tail to Earth.

Melt holes in ice shields as dust collectors

Most scientists, as well as ordinary people, assume that the Earth has been covered by a magma ocean for millions of years; This will prevent the transport and accumulation of cosmic dust for a long time. “But recent research has found evidence that the Earth’s surface cooled and solidified very rapidly, forming large ice sheets,” says Walton.

According to simulations, these ice sheets may be the best environment for cosmic dust to accumulate. Melt holes, known as cryoconite holes, on the surface of the glacier would allow the accumulation of not only sediments but also dust particles from space.

Time-related elements were cleared of dust particles. When their concentration in glacier water reaches a critical threshold, chemical reactions begin spontaneously, leading to the formation of organic molecules that are the source of life.

It is quite possible that chemical processes took place even at the icy temperatures that prevail in liquid holes: “Cold does not disrupt organic chemistry – on the contrary: reactions are more selective and specific at low temperatures than at high temperatures”, Walton. Other researchers have shown in the laboratory that simple circular ribonucleic acids (RNAs) spontaneously form and then replicate in such meltwater soups at near-freezing temperatures. The weak point of the argument may be that at low temperatures the elements needed to form organic molecules dissolve very slowly from dust particles.

The beginning of the debate about the origin of life

Walton’s theory is not controversial in the scientific community. “This research will undoubtedly spark a controversial scientific debate,” says Walton, “but it will also generate new ideas about the origins of life.”

Even in the 18th and 19th centuries, scientists believed that meteorites brought to Earth “elements of life,” as Walton called them. Even then, researchers discovered most of these elements in rocks in space, but not in the Earth’s core. “But since then, almost no one has considered the idea that prebiotic chemistry is primarily triggered by meteorites,” says Walton.

“The meteorite idea sounds interesting, but there is a problem,” Walton explains. A single meteorite provides these substances only to a limited environment; Where it lands is random and more supplies are not guaranteed. “I think it’s very unlikely that the origin of life could be traced to a few randomly scattered pieces of rock,” he says. “Instead, I think enriched cosmic dust is the likely source.”

Walton’s next step will be to test his theory experimentally. In the laboratory, he will use large reaction vessels to recreate conditions that would have prevailed in the original melting vents, then adjust the initial conditions to those that existed in the cryoconite vent probably four billion years ago, and finally wait to see if that actually happened. Any chemical reaction that produces biologically important molecules occurs.