Tryptophan, the amino acid often linked to post-Thanksgiving sleepiness, has been discovered on the asteroid Bennu. This small rock orbits Earth every six years and has just revealed more of its secrets.
This breakthrough comes from NASA’s OSIRIS-REx mission, which landed on Bennu in 2020. It collected 4.3 ounces (121.6 grams) of rock and dust, bringing it back to Earth in 2023. Now, scientists around the globe are analyzing this sample.
Studying Bennu is crucial because it offers insights into our solar system’s early days. Previous analyses of Bennu’s material uncovered 14 of the 20 amino acids essential for life on Earth, along with five nucleobases vital for DNA and RNA.
Interestingly, researchers also found amino acids in samples from another asteroid, Ryugu. This suggests that asteroids may have delivered life’s building blocks to Earth, a theory gaining favor among scientists.
Recent findings identify tryptophan in the Bennu samples, raising the count of protein-building amino acids to 15. “Finding tryptophan is significant because it’s complex and has never been seen in space before,” said José Aponte, a NASA astrochemist. He believes this indicates that the ingredients for life could have formed in space before reaching Earth.
Bennu, named after an ancient Egyptian deity linked to creation, is about a third of a mile wide. It likely broke off from a larger asteroid between 2 billion and 700 million years ago. Its composition mirrors the solar system’s early chemistry, dating back roughly 4.5 billion years, according to NASA.
The asteroid has been in orbit near Earth for about 1.75 million years. There’s a chance it could hit our planet in 2182, with scientists estimating only a 0.037% chance of that happening.
The materials found on Bennu originated from supernovas, the explosions of old stars. These cosmic events created the elements we see today in asteroids. Tryptophan and ammonia, another important chemical, were found in the Bennu samples. This highlights that essential ingredients for life might be common in space.
Angel Mojarro, a NASA researcher, remarked, “These findings show that many building blocks of life can form naturally in space.” He compared it to assembling a jigsaw puzzle, with asteroids holding pieces of the life puzzle yet to be completed.
Totaling 33 amino acids from Bennu, only 14 are used by Earth’s living organisms to build proteins. Tryptophan is an essential amino acid that humans cannot produce and must obtain through diet. More tests are necessary to confirm its presence in the Bennu sample, but experts are optimistic about its authenticity given the sample’s unspoiled condition.
George Cody, a scientist who has worked on Bennu samples, indicated his belief that these molecules genuinely originate from the asteroid. He noted a connection between the natural chemistry in our solar system and the molecules needed for life today. This reinforces the idea that the building blocks of life might have cosmic origins.
Kate Freeman, a professor at Penn State, emphasized how asteroids acted as a “grocery delivery service” for early Earth, delivering essential compounds for life.
Sara Russell, a planetary sciences professor, highlighted the importance of sample return missions, stressing that pristine materials from space are key to fully understanding our universe. She noted that tryptophan’s presence is surprising since it’s not typically found in meteorites, likely due to the destructive nature of atmospheric entry.
These discoveries not only intrigue scientists but also challenge our understanding of where life might originate. The research adds a significant piece to the puzzle of how life began, indicating that the pathways to life may be more widespread across the universe.
