The identification of tryptophan, an essential amino acid linked to the myth that eating turkey induces sleepiness, on the asteroid Bennu marks a significant discovery in the field of astrobiology, reports BritPanorama.
This finding originates from a sample collected by NASA’s OSIRIS-REx mission, which successfully landed on Bennu in 2020, retrieving 4.3 ounces (121.6 grams) of rocks and dust, and returning this material to Earth in 2023. NASA has since shared portions of this sample with researchers globally for in-depth analysis.
Research of Bennu is crucial because its composition is thought to mirror the early solar system, providing insights into the origins of life. Earlier studies had already detected 14 of the 20 amino acids necessary for life on Earth in Bennu’s samples, alongside all five biological nucleobases—key components of the genetic code in DNA and RNA.
A recent analysis has increased the tally of protein-building amino acids in the asteroid to 15 out of 20, as tryptophan was confidently, albeit not conclusively, identified. This evidence further supports the idea that essential ingredients for life may have originated in space.
“Finding tryptophan in the Bennu asteroid is a big deal because tryptophan is one of the more complex amino acids, and until now it had never been seen in any meteorite or space sample,” stated José Aponte, an astrochemist at NASA’s Goddard Space Flight Center and co-author of the study published in the journal PNAS.
Aponte added, “Seeing it form naturally in space tells us that these ingredients were already being made out in the early Solar System. That would have made it easier for life to get started.”
Jigsaw pieces
Bennu, named after an ancient Egyptian deity symbolizing creation and rebirth, measures about one-third of a mile wide. It likely fragments from a larger asteroid between 2 billion and 700 million years ago. Data suggests that it formed in the main asteroid belt between Mars and Jupiter and reflects the solar system’s composition dating back approximately 4.5 billion years.
The asteroid has been orbiting close to Earth for about 1.75 million years, with predictions indicating a possible collision in 2182, which could result in a global winter. Current estimates suggest the odds of impact stand at 1 in 2,700, or 0.037% chance.
Material from Bennu is believed to have originated from supernovas, which produced elements essential for life. This study indicates a wealth of conditions on primitive bodies like Bennu that might have contributed to the formation of the building blocks of life.
“They’re like jigsaw pieces that are not yet assembled,” said Angel Mojarro, a postdoctoral researcher in the Astrobiology Analytical Laboratory at NASA. He emphasized that finding tryptophan broadens the spectrum of amino acids produced in space that could have been delivered to Earth.
The presence of tryptophan would enhance the previously documented 33 amino acids on Bennu, joining the 14 known to aid living organisms on Earth in protein synthesis. Tryptophan falls under the essential category, as it cannot be synthesized by the human body and must be obtained through diet.
Mojarro noted that additional tests are necessary to confirm tryptophan’s presence in the analyzed 50-milligram Bennu sample. However, the pristine condition of these samples makes terrestrial contamination unlikely, according to George Cody from the Carnegie Institution for Science.
Cody remarked, “I believe these molecules are legitimately derived from the Bennu asteroid.”
NASA’s sustained interest in Bennu enhances our understanding of the molecules necessary for life found in extraterrestrial materials, suggesting a potential link between early solar system chemistry and life itself. The ramifications of this study present a significant advancement in addressing questions about the origins of life. Scientists keep observing that asteroids could have acted as delivery systems for essential compounds to the early Earth.
This research underlines the necessity for sample return missions, according to Sara Russell from the Natural History Museum in London, emphasizing that while meteorites provide valuable data, uncontaminated samples from space missions are essential for a comprehensive understanding.
The discovery of tryptophan, a first of its kind in asteroid studies, reinforces the belief that molecules integral to life may persist beyond Earth. The investigation into Bennu continues to shed light on the cosmic origins of life’s building blocks.
As scientists continue to decipher Bennu’s mysteries, the enduring question of how the ingredients for life were forged in the cosmos remains central to our understanding of life’s potential beyond our planet.
