Martian Lakes

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Wade Hampton III
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Martian Lakes

Post by Wade Hampton III » Tue Oct 03, 2017 5:41 am

ANDREW MASTERSON posted....

The mystery of ancient lakes on Mars may have been solved, according to a study published
in the journal Nature Geoscience. The research, by a team led by geophysicist Edwin Kite
from the University of Chicago in the US, provides a plausible explanation for an apparent
data inconsistency that has puzzled scientists for a while. Information compiled about
ground layers on Mars – including that gathered by the rover Curiosity – indicate that
fewer that three million years ago the planet had lakes full of liquid water. This has
been perplexing, because other data, including the lack of weathering around the lake
outflows, indicate that long before then most of the planet had become cold and dry. For
the lakes to form, therefore, there had to be a period of climate warming strong enough
to induce ice to melt in sufficient quantities to form the gigantic lakes – and long
enough to allow the lakes to endure for thousands of years, as sediment evidence suggests
they did. Kite and his colleagues used a numerical analysis to try to account for the
apparent inconsistency, and posit one scenario that would explain it. They suggest that
shifts in the planet’s axis destabilised ice sheets, causing them to shrink and shift.
Methane stored in the Martian soil and trapped beneath the ice was thus liberated and
released into the atmosphere. This, in turn, had a warming effect, melting ice and
creating the lakes. The researchers note that this proposed mechanism is “inconsistent
with many previously proposed triggers for lake-forming climates” but fits well what
they term a “methane-burst scenario”. In an accompanying editorial, Alberto Fairen of
the Centro de Astrobiología in Madrid, Spain, says that while it is unlikely that any
single mechanism is sufficient to explain the existence of Martian lakes during otherwise
arid periods, the methane-burst scenario nevertheless provides a fresh means by which to
approach the evidence.
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