03 October 2019
Washington: Examining data from NASA's Cassini mission, scientists have detected new kinds of organic compounds in ice grains of Saturn's moon Enceladus.
The newly discovered molecules were determined to be nitrogen- and oxygen-bearing compounds. On Earth, similar compounds are part of chemical reactions that produce amino acids, the building blocks of life.
"If the conditions are right, these molecules coming from the deep ocean of Enceladus could be on the same reaction pathway as we see here on Earth," said Nozair Khawaja, who led the research team of the Free University of Berlin, Germany.
"We don't yet know if amino acids are needed for life beyond Earth, but finding the molecules that form amino acids is an important piece of the puzzle," Khawaja said.
Khawaja's team used data from Cassini's Cosmic Dust Analyzer, or CDA, which detected ice grains emitted from Enceladus into Saturn's E ring.
The scientists used the CDA's mass spectrometer measurements to determine the composition of organic material in the grains.
The identified organics first dissolved in the ocean of Enceladus, then evaporated from the water surface before condensing and freezing onto ice grains inside the fractures in the moon's crust, scientists found.
Blown into space with the rising plume emitted through those fractures, the ice grains were then analyzed by Cassini's CDA.
The new findings complement the team's discovery last year of large, insoluble complex organic molecules believed to float on the surface of Enceladus' ocean.
The team went deeper with this recent work to find the ingredients, dissolved in the ocean, that are needed for the hydrothermal processes that would spur amino acid formation.
"Here we are finding smaller and soluble organic building blocks -- potential precursors for amino acids and other ingredients required for life on Earth," said co-author Jon Hillier from Free University of Berlin.
The findings were published in the journal Monthly Notices of the Royal Astronomical Society.
Although the Cassini mission ended in September 2017, the data it provided will be mined for decades.