Study shows difficulty in finding evidence of life on Mars

Date:
September 15, 2020
Source:
Cornell University
Summary:
While scientists are eager to study the red planet's soils for
signs of life, researchers must ponder a considerable new challenge:
Acidic fluids - which once flowed on the Martian surface - may have
destroyed biological evidence hidden within Mars' iron-rich clays,
according to researchers.



FULL STORY ==========================================================================
In a little more than a decade, samples of rover-scooped Martian soil
will rocket to Earth.


========================================================================== While scientists are eager to study the red planet's soils for signs
of life, researchers must ponder a considerable new challenge: Acidic
fluids -- which once flowed on the Martian surface -- may have destroyed biological evidence hidden within Mars' iron-rich clays, according to researchers at Cornell University and at Spain's Centro de Astrobiologi'a.

The researchers conducted simulations involving clay and amino acids to
draw conclusions regarding the likely degradation of biological material
on Mars.

Their paper, "Constraining the Preservation of Organic Compounds in
Mars Analog Nontronites After Exposure to Acid and Alkaline Fluids,"
published Sept. 15 in Nature Scientific Reports.

Alberto G. Faire'n, a visiting scientist in the Department of Astronomy
in the College of Arts and Sciences at Cornell, is a corresponding author.

NASA's Perseverance rover, launched July 30, will land at Mars' Jezero
Crater next February; the European Space Agency's Rosalind Franklin
rover will launch in late 2022. The Perseverance mission will collect
Martian soil samples and send them to Earth by the 2030s. The Rosalind
Franklin rover will drill into the Martian surface, collect soil samples
and analyze them in situ.

In the search for life on Mars, the red planet's clay surface soils are a preferred collection target since the clay protects the molecular organic material inside. However, the past presence of acid on the surface may
have compromised the clay's ability to protect evidence of previous life.

"We know that acidic fluids have flowed on the surface of Mars in
the past, altering the clays and its capacity to protect organics,"
Faire'n said.

He said the internal structure of clay is organized into layers, where
the evidence of biological life -- such as lipids, nucleic acids,
peptides and other biopolymers -- can become trapped and well preserved.

In the laboratory, the researchers simulated Martian surface conditions
by aiming to preserve an amino acid called glycine in clay, which had
been previously exposed to acidic fluids. "We used glycine because it
could rapidly degrade under the planet's environmental conditions,"
he said. "It's perfect informer to tell us what was going on inside our experiments." After a long exposure to Mars-like ultraviolet radiation,
the experiments showed photodegradation of the glycine molecules embedded
in the clay. Exposure to acidic fluids erases the interlayer space,
turning it into a gel-like silica.

"When clays are exposed to acidic fluids, the layers collapse and the
organic matter can't be preserved. They are destroyed," Faire'n said. "Our results in this paper explain why searching for organic compounds on
Mars is so sorely difficult." The paper's lead author was Carolina
Gil?Lozano of Centro de Astrobiologi'a, Madrid and the Universidad de
Vigo, Spain. The European Research Council funded this research.


========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Blaine Friedlander. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Carolina Gil-Lozano, Alberto G. Faire'n, Victoria Mun~oz-Iglesias,
Maite
Ferna'ndez-Sampedro, Olga Prieto-Ballesteros, Luis Gago-Duport,
Elisabeth Losa-Adams, Daniel Carrizo, Janice L. Bishop, Teresa
Fornaro, Eva Mateo- Marti'. Constraining the preservation of
organic compounds in Mars analog nontronites after exposure to
acid and alkaline fluids. Scientific Reports, 2020; 10 (1) DOI:
10.1038/s41598-020-71657-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200915121313.htm

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