Future Mars explorers may be able to get all the water they need out of the red dirt beneath their boots, a new study suggests
NASA's
Mars rover Curiosity
has found that surface soil on the Red Planet contains about 2 percent
water by weight. That means astronaut pioneers could extract roughly 2
pints (1 liter) of water out of every cubic foot (0.03 cubic meters) of
Martian dirt they dig up, said study lead author Laurie Leshin, of
Rensselaer Polytechnic Institute in Troy, N.Y.
"For me, that was
a big 'wow' moment," Leshin told SPACE.com. "I was really happy when we
saw that there's easily accessible water here in the dirt beneath your
feet. And it's probably true anywhere you go on Mars." [
The Search for Water on Mars (Photos)]
The new study is one of five papers published in the journal Science
today (Sept. 26) that report what researchers have learned about Martian
surface materials from the work Curiosity did during its first 100 days
on the Red Planet.
Soaking up atmospheric water
Curiosity touched down inside Mars' huge Gale Crater in August 2012,
kicking off a planned two-year surface mission to determine if the Red
Planet could ever have supported microbial life. It achieved that goal
in March, when it found that a spot near its landing site called
Yellowknife Bay
was indeed habitable billions of years ago.
But Curiosity did quite a bit of science work before getting to
Yellowknife Bay. Leshin and her colleagues looked at the results of
Curiosity's first extensive
Mars soil analyses, which the 1-ton rover performed on dirt that it scooped up at a sandy site called Rocknest in November 2012.
Using its Sample Analysis at Mars instrument, or SAM, Curiosity heated
this dirt to a temperature of 1,535 degrees Fahrenheit (835 degrees
Celsius), and then identified the gases that boiled off. SAM saw
significant amounts of carbon dioxide, oxygen and sulfur compounds — and
lots of
water on Mars.
SAM also determined that the soil water is rich in deuterium, a "heavy"
isotope of hydrogen that contains one neutron and one proton (as
opposed to "normal" hydrogen atoms, which have no neutrons). The water
in Mars' thin air sports a similar deuterium ratio, Leshin said.
"That tells us that the dirt is acting like a bit of a sponge and absorbing water from the atmosphere," she said.
Some bad news for manned exploration
SAM
detected some organic compounds in the Rocknest sample as well —
carbon-containing chemicals that are the building blocks of life here on
Earth. But as mission scientists reported late last year, these are
simple, chlorinated organics that likely have nothing to do with Martian
life. [
The Hunt for Martian Life: A Photo Timeline]
Instead, Leshin said, they were probably produced when organics that
hitched a ride from Earth reacted with chlorine atoms released by a
toxic chemical in the sample called perchlorate.
Perchlorate is known to exist in Martian dirt;
NASA's Phoenix lander
spotted it near the planet's north pole in 2008. Curiosity has now
found evidence of it near the equator, suggesting that the chemical is
common across the planet. (Indeed, observations by a variety of robotic
Mars explorers indicate that Red Planet dirt is likely similar from
place to place, distributed in a global layer across the surface, Leshin
said.)
The presence of perchlorate is a challenge that architects of future
manned Mars missions will have to overcome, Leshin said.
"Perchlorate is not good for people. We have to figure out, if humans
are going to come into contact with the soil, how to deal with that,"
she said.
"That's the reason we send robotic explorers before we
send humans — to try to really understand both the opportunities and
the good stuff, and the challenges we need to work through," Leshin
added.
A wealth of discoveries
At left, a closeup view of the Mars rock target Rocknest taken by
the Curiosity rover showing its sandy surface and shadows that were
disrupted by the rover's front left wheel. At right, a view of Mars
samples from Curiosity's third dirt scoop after it was seived. Image
released Sept. 26, 2013.
The four other papers published in Science today report exciting results as well.
For example, Curiosity's laser-firing ChemCam instrument found a strong
hydrogen signal in fine-grained Martian soils along the rover's route,
reinforcing the SAM data and further suggesting that water is common in
dirt across the planet (since such fine soils are globally distributed).
Another study reveals more intriguing details about a rock Curiosity
studied in October 2012. This stone — which scientists dubbed "Jake
Matijevic" in honor of a mission team member who died two weeks after
the rover touched down — is a type of volcanic rock never before seen on
Mars.
However, rocks similar to Jake Matijevic are commonly
observed here on Earth, especially on oceanic islands and in rifts where
the planet's crust is thinning out.
"Of all the Martian rocks,
this one is the most Earth-like. It's kind of amazing," said Curiosity
lead scientist John Grotzinger, a geologist at the California Institute
of Technology in Pasadena. "What it indicates is that the planet is more
evolved than we thought it was, more differentiated."
This image depicts the science result from the Mars rover
Curiosity's CheMin instrument, showing an X-ray diffraction of the
rover's fifth scoop of Martian dirt. The black semi-circle at the bottom
is the shadow of the beam stop. Image released Sept. 26, 2013.
The five new studies showcase the diversity and scientific value of
Gale Crater,
Grotzinger said. They also highlight how well Curiosity's 10 science
instruments have worked together, returning huge amounts of data that
will keep the mission team busy for years to come.
"The amount
of information that comes out of this rover just blows me away, all the
time," Grotzinger told SPACE.com. "We're getting better at using
Curiosity, and she just keeps telling us more and more. One year into
the mission, we still feel like we're drinking from a fire hose."
The road to Mount Sharp
The pace of discovery could pick up even more. This past July, Curiosity left the Yellowknife Bay area and headed for
Mount Sharp, which rises 3.4 miles (5.5 kilometers) into the Martian sky from Gale Crater's center.
Mount Sharp has been Curiosity's main destination since before the
rover's November 2011 launch. Mission scientists want the rover to climb
up through the mountain's foothills, reading the terrain's many layers
along the way.
"As we go through the rock layers, we're
basically looking at the history of ancient environments and how they
may be changing," Grotzinger said. "So what we'll really be able to do
for the first time is get a relative chronology of some substantial part
of Martian history, which should be pretty cool."
Curiosity has
covered about 20 percent of the planned 5.3-mile (8.5 km) trek to Mount
Sharp. The rover, which is doing science work as it goes, may reach the
base of the mountain around the middle of next year, Grotzinger said.
Source
Alcune immagini a colori scattate di recente mostrano il nucleo di ISON ingrossato e di colore verde.
