Scientists at Aarhus University have overturned a long-standing assumption about how life’s essential ingredients emerge. Recent experiments show that the essential components needed to construct proteins can form naturally in space, a finding that increases the likelihood that life could exist elsewhere within the universe.
The research was carried out at advanced laboratories at Aarhus University and at a European research facility in Hungary (HUN-REN Atomki). The experiments were led by researchers Sergio Ioppolo and Alfred Thomas Hopkinson.
Recreating the Extreme Conditions of Interstellar Space
Inside a specially designed chamber, the researchers recreated the cruel environment present in vast clouds of cosmic dust positioned hundreds of light-years from Earth. These regions are among the many coldest and emptiest places within the universe.
Temperatures in such dust clouds reach about -260°C, and pressure is so low that researchers must continuously remove stray gas particles to take care of an ultra-high vacuum. Under these rigorously controlled conditions, the team studied how particles behave when exposed to radiation, closely matching what happens in real interstellar space.
“We already know from earlier experiments that straightforward amino acids, like glycine, form in interstellar space. But we were focused on discovering if more complex molecules, like peptides, form naturally on the surface of dust grains before those participate within the formation of stars and planets,” Sergio Ioppolo says.
From Amino Acids to Protein Precursors
Peptides are short chains made when individual amino acids link together. When many peptides bond, they form proteins, that are essential for all times as we understand it. Identifying where and the way these protein precursors originate is a key step in understanding how life might begin.
To check this process, the researchers placed glycine contained in the chamber and exposed it to simulated cosmic rays using an ion accelerator at HUN-REN Atomki. They then analyzed the chemical reactions that followed.
“We saw that the glycine molecules began reacting with one another to form peptides and water. This means that the identical process occurs in interstellar space,” Alfred Thomas Hopkinson says. “It is a step toward proteins being created on dust particles, the identical materials that later form rocky planets.”
Star-Forming Clouds as Chemical Factories
Ioppolo, Hopkinson, and their colleagues give attention to giant dust clouds between stars because these regions are where latest solar systems are born. For a long time, scientists believed that only quite simple molecules could form in these environments.
“We used to think that only quite simple molecules may very well be created in these clouds. The understanding was that more complex molecules formed much later, once the gases had begun coalescing right into a disc that eventually becomes a star,” Sergio Ioppolo explains.
“But we’ve shown that that is clearly not the case.”
This shift in understanding suggests that key life-related molecules are way more widespread throughout the universe than previously thought.
Implications for Life Beyond Earth
As interstellar dust clouds collapse, they eventually give rise to stars and planets. During this process, tiny chemical constructing blocks could be delivered to newly formed rocky worlds.
“Eventually, these gas clouds collapse into stars and planets. Little by little, these tiny constructing blocks land on rocky planets inside a newly formed solar system. If those planets occur to be within the habitable zone, then there’s an actual probability that life might emerge,” Sergio Ioppolo says.
“That said, we still do not know exactly how life began. But research like ours shows that most of the complex molecules essential for all times are created naturally in space.”
A Chemical Process That Works In all places
At first glance, the formation of peptides from easy amino acids might seem to be a small step. Nevertheless, the chemical response that links amino acids together follows the identical basic rules all over the place, making the invention especially vital.
“Every kind of amino acids bond into peptides through the identical response. It’s, due to this fact, very likely that other peptides naturally form in interstellar space as well,” says Hopkinson. “We have not looked into this yet, but we’re prone to achieve this in the longer term.”
Looking for Other Ingredients of Life
Proteins are only a part of the image. Life also depends upon membranes, nucleobases, and nucleotides. Whether these components may form naturally in space remains to be an open query.
Researchers on the Center for Interstellar Catalysis, funded by The Danish National Research Foundation, are continuing to research these possibilities.
“These molecules are a few of the key constructing blocks of life,” explained co-author Professor Liv Hornekær, the InterCat center leader. “They could actively take part in early prebiotic chemistry, catalyzing further reactions that lead toward life.”
“There’s still rather a lot to be discovered, but our research team is working on answering as lots of these basic questions as possible,” Sergio Ioppolo says. “We have already discovered that most of the constructing blocks of life are formed on the market, and we’ll likely find more in the longer term.”