Nasa's Curiosity rover finds water in Martian soil

Water has been discovered in the
fine-grained soil on the surface of
Mars, which could be a useful
resource for future human missions
to the red planet, according to
measurements made by Nasa's
Curiosity rover.
Each cubic foot of Martian soil
contains around two pints of liquid
water, though the molecules are not
freely accessible, but rather bound to
other minerals in the soil.
The Curiosity rover has been on Mars
since August 2012 , landing in an area
near the equator of the planet known
as Gale Crater. Its target is to circle
and climb Mount Sharp, which lies at
the centre of the crater, a five-
kilometre-high mountain of layered
rock that will help scientists unravel
the history of the planet.
On Thursday Nasa scientists
published a series of five papers in
the journal Science , which detail the
experiments carried out by the
various scientific instruments aboard
Curiosity in its first four months on
the martian surface. Though
highlights from the year-long mission
have been released at conferences
and Nasa press conferences, these are
the first set of formal, peer-reviewed
results from the Curiosity mission.
"We tend to think of Mars as this dry
place – to find water fairly easy to get
out of the soil at the surface was
exciting to me," said Laurie Leshin,
dean of science at Rensselaer
Polytechnic Institute and lead author
on the Science paper which
confirmed the existence of water in
the soil . "If you took about a cubic
foot of the dirt and heated it up,
you'd get a couple of pints of water
out of that – a couple of water bottles'
worth that you would take to the
gym."
About 2% of the soil, by weight, was
water. Curiosity made the
measurement by scooping up a
sample of the Martian dirt under its
wheels, sieving it and dropping tiny
samples into an oven in its belly, an
instrument called Sample Analysis at
Mars. "We heat [the soil] up to 835C
and drive off all the volatiles and
measure them," said Leshin. "We have
a very sensitive way to sniff those
and we can detect the water and
other things that are released."
Aside from water, the heated soil
released sulphur dioxide, carbon
dioxide and oxygen as the various
minerals within it were decomposed
as they warmed up.
One of Curiosity's main missions is to
look for signs of habitability on Mars,
places where life might once have
existed. "The rocks and minerals are
a record of the processes that have
occurred and [Curiosity is] trying to
figure out those environments that
were around and to see if they were
habitable," said Peter Grindrod, a
planetary scientist at University
College London who was not involved
in the analyses of Curiosity data.
Flowing water is once thought to have
been abundant on the surface of
Mars, but it has now all but
disappeared. The only direct sources
of water found so far have been as
ice at the poles of the planet.
The other papers included x-ray
diffraction images of the soil in order
to work out the crystalline structure
of the minerals on the Martian
surface and analysis of a volcanic
rock called "Jake_M" , which is named
after a Nasa engineer. The analysis
showed that the rock was similar to a
type on Earth known as a mugearite,
which is typically found on ocean
islands and in rift zones.
Grindrod said that the latest results
published by the Nasa team were just
the start of the scientific insights that
would come from Mars in the next
few years. "It's the first flexing of
Curiosity's analytical muscles," he
said. "Curiosity spent a long time
checking out the engineering,
instruments and procedures it was
going to use – these papers cover just
that engineering period. The targets
here weren't chosen because of their
science goals as such but as good
targets to test out the instruments."
Leshin said that, as well as the
excitement of exploring a new world
for the first time, the increasingly
detailed analysis of the Martian
surface would be critical information
for planning human missions. As
well as the water discovery, analysis
of the soil has also shown, for
example, the presence of a type of
chemical called a perchlorate, which
is can be toxic to people. "It's only
there at a 0.5% level in the soil but it
impedes thyroid function," she said.
"If humans are there and are coming
into contact with fine-grained dust,
we have to think about how we live
with that hazard. To me it's a good
connection between the science we do
and the future human exploration of
Mars."
She added: "I do think it's inevitable
that we'll send people there and so
let's do its as smartly as we can. Let's
get as smart as we can before we go