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| A photograph obtained from the European Space Agency on July 25, 2018, shows an artist's impression of Mars Express over a background based on an actual image of the Red Planet taken by the spacecraft |
A massive underground lake has been detected for the first time on Mars, raising hopes that more water -- and maybe even life -- exists there, international astronomers said Wednesday.
Located
under a layer of Martian ice, the lake is about 12 miles (20 kilometers) wide,
said the report led by Italian researchers in the US journal Science.
It is the
largest body of liquid water ever found on the Red Planet.
"Water
is there. We have no more doubt," co-author Enrico Flamini, the Italian
space agency's Mars Express mission manager, told a press conference.
Mars is now
cold, barren and dry but it used to be warm and wet. It was home to plenty of
liquid water and lakes at least 3.6 billion years ago.
Scientists
are eager to find signs of contemporary water, because such discoveries are key
to unlocking the mystery of whether life ever formed on Mars in its ancient
past, and whether it might persist today.
"This
is a stunning result that suggests water on Mars is not a temporary trickle
like previous discoveries but a persistent body of water that provides the
conditions for life for extended periods of time," said Alan Duffy, an
associate professor at Swinburne University in Australia, who was not involved
in the study.
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An image
released by the European Space Agency on July 25, 2018, shows radar
data
collected by the Mars Express orbiter pointing to a pond of liquid water buried
under layers of ice and dust in the south polar region of Mars
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Being able
to access water sources could also help humans survive on a future crewed mission
to Earth's neighboring planet, with NASA aiming to send explorers in the 2030s.
This
particular lake, however, would be neither swimmable nor drinkable, and it lies
almost a mile deep (1.6 kilometers) beneath the icy surface in a harsh and
frigid environment.
Whether
microbial forms of life could lie within is a matter of debate.
Some
experts are skeptical of the possibility since the lake is so cold and briny,
mixed with a heavy dose of dissolved Martian salts and minerals.
The
temperature is likely below the freezing point of pure water, but the lake can
remain liquid due to the presence of magnesium, calcium and sodium.
"This
is a discovery of extraordinary significance, and is bound to heighten
speculation about the presence of living organisms on the Red Planet,"
said Fred Watson of the Australian Astronomical Observatory.
"Caution
needs to be exercised, however, as the concentration of salts needed to keep
the water liquid could be fatal for any microbial life similar to
Earth's," added Watson, who was not involved in the research.
Radar
detection
The
discovery was made using a radar instrument on board the European Space
Agency's Mars Express orbiter, which launched in 2003.
The tool is
called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS),
and was designed to find subsurface water by sending radar pulses that
penetrate the surface and ice caps.
MARSIS
"then measures how the radio waves propagate and reflect back to the
spacecraft," said the study.
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A
photograph from NASA's Mars Reconnaissance Orbiter of Gorgonum Basin within
the
Red Planet's Terra Sirenum region, which scientists think once had a large lake
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These
reflections "provide scientists with information about what lies beneath
the surface."
A team of
researchers led by Roberto Orosei of the National Institute for Astrophysics in
Bologna, Italy, surveyed a region called Planum Australe, located in the
southern ice cap of Mars, from May 2012 until December 2015.
A total of
29 sets of radar samplings showed a "very sharp change in its associated
radar signal," allowing scientists to map the outlines of the lake.
"The
radar profile of this area is similar to that of lakes of liquid water found
beneath the Antarctic and Greenland ice sheets on Earth, suggesting that there
is a subglacial lake at this location on Mars," said the report.
Researchers
said they are not sure how far down it goes, but that it may be around three
feet (one meter) deep.
Confirmation needed
"This
is the first body of water it has detected, so it is very exciting," David
Stillman, a senior research scientist in the Department of Space Studies at
Southwest Research Institute in San Antonio, Texas, told AFP in an email.
However,
Stillman, who was not involved in the research, said another spacecraft, or
other instruments, need to be able to confirm the discovery.
He noted
that a higher-frequency radar instrument made by the Italian space agency
SHARAD, on board the Mars Reconnaissance Orbiter launched in 2005, has been
unable to detect subsurface water.
"It is
strange that SHARAD cannot confirm this discovery. In fact, SHARAD cannot
penetrate through the ice here and no one understands why it can't,"
Stillman said.
"This
suggests that something strange is going on here. Thus, I'm skeptical about
this discovery."
But
researchers are excited about the potential for future finds, because if liquid
water could be found at Mars's south pole, it might be elsewhere too.
"There's
nothing special about this location other than the MARSIS radar on the Mars
Express spacecraft is most sensitive to that region," said Duffy.
"There
are likely similar water deposits below the ground all across Mars."
Infographic on Mars after a massive underground lake was detected on the Red Planet pic.twitter.com/o6lo8nQFbV— AFP news agency (@AFP) July 28, 2018
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