Scientists have discovered ancient salt water and building blocks of life in a capsule of asteroid fragments returned by NASA’s OSIRIS-REx spacecraft. The findings suggest that life-friendly chemistry could be more common in space than previously thought.
The asteroid, Bennu, is about 4.5 billion years old and offers a glimpse into the solar system’s early days. When analyzed under specialized microscopes, scientists found evidence of sodium carbonates, minerals that commonly occur on Earth as “soda ash” or in dried-up lake beds. This discovery indicates that Bennu had pockets of liquid water, which evaporated and left behind salty, brine-like residues rich in life-supporting elements.
The presence of these elements raises questions about how early Earth got its ingredients for life. Phosphates can help make sugars, while clays can help make nucleotides that build RNA and DNA. Sodium brines are also essential to speeding up reactions and releasing molecules after they form.
A second study found amino acids, the building blocks of proteins, in the sample, as well as the five main nucleobases that make up RNA and DNA. These findings echo what researchers have long suspected about asteroids ferrying essential organic molecules across the solar system.
The discovery is a significant step forward in understanding the origins of life on Earth. The asteroid Bennu’s brines may have created a nursery for complex organic molecules, which were then delivered to a nascent Earth.
While the discovery is promising, more research is needed to understand how these raw components can produce life. Scientists will continue to analyze the samples and study the tiny traces of water locked within the minerals to answer longstanding questions about where Earth’s water came from.
Source: https://www.smithsonianmag.com/smart-news/scientists-discover-traces-of-salt-water-and-building-blocks-of-life-in-nasas-samples-from-the-asteroid-bennu-180985924