Tryptophan Found On Asteroid Bennu Strengthens Clues To Life’s Building Blocks

The discovery of tryptophan in Bennu’s regolith is a breakthrough in astrobiology. Amino acids are fundamental to life, serving as the building blocks of proteins. While simpler amino acids have been detected in meteorites before, tryptophan’s identification is unprecedented and suggests that complex organic chemistry was active in the early Solar System. Scientists believe Bennu’s aqueous and alkaline environment facilitated the formation of these compounds, preserving them in pristine condition until their recovery by OSIRIS-REx.  

Key highlights from the announcement include  

• Tryptophan was detected for the first time in asteroid material, expanding the catalog of extraterrestrial amino acids.  
• The OSIRIS-REx mission returned 121.6 grams of Bennu’s dust and rocks, enabling high-sensitivity organic analysis.  
• Samples revealed 14 of the 20 amino acids used by terrestrial life, alongside five nucleobases central to RNA and DNA.  
• Distinct rock types in Bennu showed heterogeneous organic signatures, shaped by aqueous alteration in a wet, alkaline environment.  
• The findings strengthen theories that asteroids and comets delivered prebiotic compounds to early Earth.  
• Pristine curation protocols ensured minimal contamination, allowing scientists to confirm delicate organics with high confidence.  
• The discovery underscores the importance of future sample-return missions for advancing astrobiology.  
• Researchers plan isotopic fingerprinting and phase mapping to trace synthesis pathways and transport histories of these compounds.  

This milestone elevates Bennu’s role as a key repository of prebiotic chemistry. By linking complex organics to geological contexts, scientists gain deeper insight into how life’s ingredients may have been distributed across the Solar System. The detection of tryptophan not only broadens our understanding of extraterrestrial chemistry but also strengthens the hypothesis that life’s precursors were seeded on Earth through asteroid impacts.  

Sources: NASA OSIRIS-REx Mission, PNAS, CNN Science, International Business Times