Curiosity rover detects long-chain carbon molecules on Mars

https://www.science.org/content/article/curiosity-rover-detects-long-chain-carbon-molecules-mars
NASA’s Curiosity rover has detected what
could be a chemical relic of long-ago life
on Mars: long-chain organic molecules. Found
after painstaking reanalysis of data on a
sample drilled from a lake that dried up
billions of years ago, the molecules likely
derived from fatty acids, a common building
block of cell membranes on Earth. The finding,
published today in the Proceedings of the
National Academy of Sciences, is not a
definite detection of past life; the fatty
acids could also have formed without life.
But it’s another in a series of tantalizing
hints.
“This is an amazing result,” says Monica
Grady, a planetary scientist at the Open
University who wasn’t involved in the new
research. If these are “breakdown products
from carboxylic acids, then we are seeing
something very exciting indeed.” It also
suggests Curiosity’s successor,
Perseverance, will find similar molecules,
says Jack Mustard, a planetary scientist
at Brown University. Perseverance is
collecting samples for an ambitious effort
to return Mars rocks to labs on Earth,
where scientists will be able to reach
more definitive conclusions on the
molecules’ origins.
https://www.pnas.org/doi/abs/10.1073/pnas.2420580122
Long-chain alkanes preserved in a Martian mudstone
Significance
Decane, undecane, and dodecane were detected
in a Martian sample at the tens of pmol level
and may originate from long-chain carboxylic
acids. The detection of long-chain alkanes in
the Sheepbed mudstone is important for
extending studies of habitability on Mars as
the Curiosity rover continues to map out
windows of high preservation potential for
chemically reduced organic compounds. The
provenance and distribution of these molecules
are of high interest in the search for
potential biosignatures on Mars.
Abstract
Organic molecules preserved in ancient Martian
rocks provide a critical record of the past
habitability of Mars and could be chemical
biosignatures. Experiments conducted by the
Sample Analysis at Mars instrument onboard
the Curiosity rover have previously reported
several classes of indigenous chlorinated and
sulfur-containing organic compounds in Gale
crater sedimentary rocks, with chemical
structures of up to six carbons. Here, we
report the detection of decane (C10H22),
undecane (C11H24), and dodecane (C12H26) at
the tens of pmol level, released from the
Cumberland drilled mudstone sample, using a
modified SAM analytical procedure optimized
for the detection of larger organic molecules.
Laboratory experiments support the hypothesis
that the alkanes detected were originally
preserved in the mudstone as long-chain
carboxylic acids. The origin of these
molecules remains uncertain, as they could
be derived from either abiotic or biological
sources.