All of the bases in DNA and RNA have now been discovered in meteorites that fell to Earth

In a groundbreaking discovery, scientists have found all five bases that store information in DNA and RNA in meteorites that fell to Earth within the last century. 

These nucleobases - adenine, guanine, cytosine, thymine, and uracil - combine with sugars and phosphates to make up the genetic code of all life on Earth. The discovery adds to the growing body of evidence suggesting that life's precursors may have originated from space.

Adenine, guanine, and other organic compounds have been detected in meteorites since the 1960s. Hints of uracil have also been observed, but cytosine and thymine remained elusive until now. 

The recent discovery was made possible by a new technique developed by geochemist Yasuhiro Oba of Hokkaido University in Sapporo, Japan, and his colleagues. This method gently extracts and separates different chemical compounds in liquified meteorite dust for analysis.

The researchers used this technique to analyze samples from four meteorites that fell decades ago in Australia, Kentucky, and British Columbia. They detected and measured adenine, guanine, cytosine, uracil, thymine, several compounds related to these bases, and a few amino acids. 

The team also measured chemical abundances within soil collected from the Australia site and compared the measured meteorite values with that of the soil. The results suggest that the compounds came to Earth in these rocks.

However, the origin of some detected compounds, including cytosine and uracil, remains uncertain due to the possibility of earthly contamination. Future studies, including the analysis of samples from the asteroid Ryugu brought to Earth by Japan's Hayabusa2 mission, and samples from the asteroid Bennu expected to be returned by NASA's OSIRIS-REx mission in September 2023, may provide further insights.

Research Paper

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