New research has found that interstellar clouds may have played a significant role in creating the conditions that helped create the building blocks of life.
Amino acids, a key ingredient of life, could have originally been made in interstellar molecular clouds like the one that Solar system is formed, before it is wound up in asteroids which later crashed The earthand takes the amino acids with it.
Carbonaceous chondrite meteorites are rich in amino acids and amines (the latter are nitrogen-containing organic compounds) which are crucial components of proteins and biological cells in life on The earth. Understanding where and how amino acids are formed is therefore important to better understand the origin of life.
Researchers led by Danna Qasim of the Southwest Research Institute (SwRI) in San Antonio, Texas, and Christopher Materese of NASA’s Goddard Space Flight Center has taken a major step toward figuring out where amino acids and amines form in space by creating them in a lab under “asteroid-relevant conditions.”
Related: Asteroid Ryugu is rich in organic molecules that could be the building blocks of life
Many studies have focused on trying to simulate the formation of amino acids in carbonaceous chondrites, which are meteorites from carbon-rich asteroids formed at the dawn of the solar system, 4.5 billion years ago. Qasim and Materese’s research takes things even further back in time to the interstellar cloud of molecular gas and dust from which the sun and planets eventually formed.
“The composition of asteroids derives from the parent interstellar molecular cloud, which was rich in organic matter,” Qasim said in a statement (opens in new tab) from SWRI. “Although there is no direct evidence for amino acids in interstellar clouds, there is evidence for amines. The molecular cloud could have provided the amino acids in asteroids, which passed them on to meteorites.”
So Qasim began replicating conditions in interstellar clouds to try to form amino acids. She used ices such as ammonia, carbon dioxide, methanol and water commonly found in interstellar clouds and bombarded them with high energy protons from a Van de Graff generator to replicate the ices irradiated in space by cosmic rays. The proton bombardment shattered the ice molecules, with the constituent parts then reassembling themselves as more complex organic molecules, including amines and amino acids such as ethylamine and glycine, in what Qasim calls an “organic residue” — a kind of frothy slime.
When the solar system formed from the molecular cloud, these amines and amino acids would have been transferred to carbonaceous asteroids and eventually brought to Earth by asteroid impacts and meteorite falls. But the abundance of amines and amino acids that Qasim created does not match their abundance of carbonaceous chondrites.
Materese wondered if there was an extra stage where more amines and amino acids are formed inside the asteroids, which were still warm and contained liquid water at the time shortly after formation.
Qasim and Materese’s team further processed the samples of organic residue under conditions similar to those of the asteroids. They found that not only did the proportions of amines and amino acids from the interstellar cloud remain intact, but the amount of some of the amino acids, such as glycine, doubled after 7 days of water changes in the heat and water.
“The important thing is that the building blocks of life have a strong connection not only to processes in the asteroid, but also to the processes in the interstellar cloud’s parent cloud,” Qasim said in a statement (opens in new tab) from NASA.
However, there is a caveat. Even accounting for asteroid processing, abundances of amines and amino acids still do not quite match the amounts found in carbonaceous chondrite meteorites. It is possible that after falling to Earth, the meteorites became contaminated with organic material on Earth, changing their amino acids. As such, Qasim and Materese, along with many of their colleagues, are eagerly awaiting the return of samples from the carbonaceous asteroid Bennuwhich was visited by NASA OSIRIS-REx mission. These samples will parachute back to Earth in their capsule on September 24, 2023and will represent pristine materials uncontaminated by life on Earth dating back to the birth of the solar system.
Along with recent detailed information on the ice composition of interstellar clouds from JWSTscientists can finally determine with certainty whether amino acids were formed in our solar system or in interstellar space.
If the former, then it is possible that life could be unique to our solar system. If the latter, then amino acids should be spread far and wide Milky Waywhich increases the potential for life on planets around other stars.
The research was published on January 9 in the journal ACS Earth and Space Chemistry (opens in new tab).
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