The origins of the building blocks of life - Astronomy and astrophysics news

The origins of the building blocks of life – Astronomy and astrophysics news

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A new study by Southwest Research Institute research scientist Dr. Danna Qasim posits that interstellar cloud conditions may have played an important role in determining the presence of key building blocks of life in the solar system.

“Carbonaceous chondrites, among the oldest objects in the universe, are meteorites that are thought to have contributed to the origins of life. They contain several different organic molecules and substances, including amines and amino acids, which are key building blocks of life that were essential for the creation of life on Earth. These substances are needed to create protein and muscle tissue,” Qasim said.

Most meteorites are fragments of asteroids that disintegrated long ago in the asteroid belt, located between Mars and Jupiter. Such fragments orbit the Sun – sometimes for millions of years – before colliding with Earth.

One of the questions Qasim and others are trying to answer is how amino acids got into carbonaceous chondrites in the first place. Since most meteorites come from asteroids, scientists have attempted to replicate amino acids by simulating asteroid conditions in a laboratory environment, a process called “aqueous weathering.”

“This method was not 100% successful,” Qasim said. “However, the composition of the asteroids comes from the parental interstellar molecular cloud, which was rich in organic matter. 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 transmitted them to meteorites. »

To determine to what extent amino acids formed from asteroid conditions and to what extent they were inherited from the interstellar molecular cloud, Qasim simulated the formation of amines and amino acids as it would occur in the interstellar molecular cloud.

“I created ices that are very common in the cloud and irradiated them to simulate the impact of cosmic rays,” said Qasim, who conducted the experiment while working at Goddard Space Flight Center in NASA in Greenbelt, Maryland, between 2020 and 2022. “This caused molecules to break up and recombine into larger molecules, which ultimately created an organic residue. »

Qasim then reprocessed the residue recreating the conditions of an asteroid through aqueous weathering and studied the substance, looking for amines and amino acids.

“No matter what kind of asteroid processing we did, the amine and amino acid diversity of the interstellar ice experiments remained constant,” she said. “This tells us that interstellar cloud conditions are quite resistant to asteroid processing. These conditions may have influenced the distribution of amino acids we find in meteorites. »

However, individual amino acid abundances doubled, suggesting that asteroid processing influences the amount of amino acids present.

“Essentially, we need to consider both the interstellar cloud conditions and the asteroid processing to best interpret the distribution,” she said.

Qasim looks forward to studies of asteroid samples from missions such as OSIRIS-REx, which is currently on its way back to Earth to deliver samples from asteroid Bennu here in September, and Hayabusa2, which is recently returned from the asteroid Ryugu, to better understand the role played by the interstellar cloud in the distribution of the building blocks of life.

“When scientists study these samples, they’re usually trying to figure out what asteroid processes are influencing, but clearly we now need to figure out how the interstellar cloud is also influencing the distribution of the building blocks of life,” Qasim said.

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