Bennu's Frozen Secrets: A New Origin Story for Life's Building Blocks

Imagine a time when the Solar System was still in its formative stages, and the building blocks of life were being forged in the frozen depths of space.

TL;DR
• Bennu's amino acids likely formed in the frozen outer Solar System, not in warm asteroid interiors.
• This discovery challenges traditional assumptions about the origins of life's building blocks.
• The early Solar System produced life's ingredients through various pathways in both frozen and wet conditions.

Summary
The analysis of samples from asteroid Bennu has led to a significant discovery about the origin of amino acids, the building blocks of life. These amino acids likely formed in the frozen outer reaches of the early Solar System, rather than in the warm interiors of asteroids as previously thought.

The research team from Penn State used custom instruments to measure isotopes in the samples, which provided clues about the chemical environments and processes that led to the formation of these molecules. The findings suggest that the early Solar System was a distributed chemical laboratory with multiple active sites producing life's ingredients through different pathways.

Key insights from the study include:
• The amino acids in Bennu's samples have chemical fingerprints that point to a frozen origin, with uniform isotopic patterns suggesting they formed from a single source.
• The nitrogen isotopes in Bennu's amino acids are dramatically enriched, but do not match the free ammonia measured in other samples, challenging the traditional water-based formation pathway.
• The D and L versions of glutamic acid in Bennu's samples have different nitrogen isotope values, despite being mirror images, which challenges fundamental assumptions about amino acid chemistry.

The study's findings have implications for understanding how life's ingredients were delivered to early Earth. The diversity of chemical pathways that produced amino acids in the early Solar System may have provided a richer starting material for life to emerge.

The research was published in the Proceedings of the National Academy of Sciences and was supported by NASA and other institutions.

The discovery of Bennu's frozen amino acids opens a new chapter in our understanding of the origins of life, inviting us to re-examine the complex and dynamic history of our Solar System.