May 25, 2018
University of Edinburgh
Iron-rich rocks near ancient
lake sites on Mars could hold vital clues that show life once existed there,
research suggests.
Iron-rich rocks near ancient
lake sites on Mars could hold vital clues that show life once existed there,
research suggests.
These rocks -- which formed in
lake beds -- are the best place to seek fossil evidence of life from billions
of years ago, researchers say.
A new study that sheds light
on where fossils might be preserved could aid the search for traces of tiny
creatures -- known as microbes -- on Mars, which it is thought may have
supported primitive life forms around four billion years ago.
A team of scientists has
determined that sedimentary rocks made of compacted mud or clay are the most
likely to contain fossils. These rocks are rich in iron and a mineral called
silica, which helps preserve fossils.
They formed during the
Noachian and Hesperian Periods of Martian history between three and four
billion years ago. At that time, the planet's surface was abundant in water,
which could have supported life.
The rocks are much better
preserved than those of the same age on Earth, researchers say. This is because
Mars is not subject to plate tectonics -- the movement of huge rocky slabs that
form the crust of some planets -- which over time can destroy rocks and fossils
inside them.
The team reviewed studies of
fossils on Earth and assessed the results of lab experiments replicating
Martian conditions to identify the most promising sites on the planet to
explore for traces of ancient life.
Their findings could help
inform NASA's next rover mission to the Red Planet, which will focus on
searching for evidence of past life. The US space agency's Mars 2020 rover will
collect rock samples to be returned to Earth for analysis by a future mission.
A similar mission led by the
European Space Agency is also planned in coming years.
The latest study of Mars rocks
-- led by a researcher from the University of Edinburgh -- could aid in the
selection of landing sites for both missions. It could also help to identify
the best places to gather rock samples.
The study, published in Journal
of Geophysical Research, also involved researchers at NASA's Jet Propulsion
Laboratory, Brown University, California Institute of Technology, Massachusetts
Institute of Technology and Yale University in the US.
Dr Sean McMahon, a Marie
Sklodowska-Curie fellow in the University of Edinburgh's School of Physics and
Astronomy, said: "There are many interesting rock and mineral outcrops on
Mars where we would like to search for fossils, but since we can't send rovers
to all of them we have tried to prioritise the most promising deposits based on
the best available information."
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