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New Organic Compounds Found in Enceladus Ice Grains New
kinds of organic compounds, the ingredients of amino acids, have been detected in
the plumes bursting from Saturn's moon Enceladus. The findings are the result
of the ongoing deep dive into data from NASA's Cassini mission.
Powerful hydrothermal vents eject material
from Enceladus' core, which mixes with water from the moon's massive subsurface
ocean before it is released into space as water vapor and ice grains. The newly
discovered molecules, condensed onto the ice grains, 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. Hydrothermal vents on the ocean floor
provide the energy that fuels the reactions. Scientists believe Enceladus'
hydrothermal vents may operate in the same way, supplying energy that leads to
the production of amino acids.
"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. 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," said
Nozair Khawaja, who led the research team of the Free University of Berlin. His
findings
were published Oct. 2 in the Monthly Notices of the Royal
Astronomical Society.
Although
the Cassini mission ended in September 2017, the data it provided will be mined
for decades. Khawaja's team used data from the spacecraft'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.
"This
work shows that Enceladus' ocean has reactive building blocks in abundance, and
it's another green light in the investigation of the habitability of Enceladus,"
added co-author Frank Postberg.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency (ESA) and the Italian Space Agency. NASA's Jet Propulsion
Laboratory, a division of Caltech in Pasadena, California, manages the mission
for NASA's Science Mission Directorate, Washington. JPL designed, developed and
assembled the Cassini orbiter. The radar instrument was built by JPL and the
Italian Space Agency, working with team members from the U.S. and several
European countries.
More information about Cassini can be found here:
https://solarsystem.nasa.gov/cassini
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