[meteorite-list] NASA Confirms Evidence That Liquid Water Flows on Today's Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 28 Sep 2015 12:55:03 -0700 (PDT)
Message-ID: <201509281955.t8SJt3Gk021186_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4722

NASA Confirms Evidence That Liquid Water Flows on Today's Mars
Jet Propulsion Laboratory
September 28, 2015

New findings from NASA's Mars Reconnaissance Orbiter (MRO) provide the
strongest evidence yet that liquid water flows intermittently on present-day
Mars.

Using an imaging spectrometer on MRO, researchers detected signatures
of hydrated minerals on slopes where mysterious streaks are seen on the
Red Planet. These darkish streaks appear to ebb and flow over time. They
darken and appear to flow down steep slopes during warm seasons, and then
fade in cooler seasons. They appear in several locations on Mars when
temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius),
and disappear at colder times.

"Our quest on Mars has been to 'follow the water,' in our search for life
in the universe, and now we have convincing science that validates what
we've long suspected," said John Grunsfeld, astronaut and associate administrator
of NASA's Science Mission Directorate in Washington. "This is a significant
development, as it appears to confirm that water -- albeit briny -- is
flowing today on the surface of Mars."

These downhill flows, known as recurring slope lineae (RSL), often have
been described as possibly related to liquid water. The new findings of
hydrated salts on the slopes point to what that relationship may be to
these dark features. The hydrated salts would lower the freezing point
of a liquid brine, just as salt on roads here on Earth causes ice and
snow to melt more rapidly. Scientists say it's likely a shallow subsurface
flow, with enough water wicking to the surface to explain the darkening.


"We found the hydrated salts only when the seasonal features were widest,
which suggests that either the dark streaks themselves or a process that
forms them is the source of the hydration. In either case, the detection
of hydrated salts on these slopes means that water plays a vital role
in the formation of these streaks," said Lujendra Ojha of the Georgia
Institute of Technology (Georgia Tech) in Atlanta, lead author of a report
on these findings published Sept. 28 by Nature Geoscience.

Ojha first noticed these puzzling features as a University of Arizona
undergraduate student in 2010, using images from the MRO's High Resolution
Imaging Science Experiment (HiRISE). HiRISE observations now have documented
RSL at dozens of sites on Mars. The new study pairs HiRISE observations
with mineral mapping by MRO's Compact Reconnaissance Imaging Spectrometer
for Mars (CRISM).

The spectrometer observations show signatures of hydrated salts at multiple
RSL locations, but only when the dark features were relatively wide. When
the researchers looked at the same locations and RSL weren't as extensive,
they detected no hydrated salt.

Ojha and his co-authors interpret the spectral signatures as caused by
hydrated minerals called perchlorates. The hydrated salts most consistent
with the chemical signatures are likely a mixture of magnesium perchlorate,
magnesium chlorate and sodium perchlorate. Some perchlorates have been
shown to keep liquids from freezing even when conditions are as cold as
minus 94 degrees Fahrenheit (minus 70 Celsius). On Earth, naturally produced
perchlorates are concentrated in deserts, and some types of perchlorates
can be used as rocket propellant.

Perchlorates have previously been seen on Mars. NASA's Phoenix lander
and Curiosity rover both found them in the planet's soil, and some scientists
believe that the Viking missions in the 1970s measured signatures of these
salts. However, this study of RSL detected perchlorates, now in hydrated
form, in different areas than those explored by the landers. This also
is the first time perchlorates have been identified from orbit.

MRO has been examining Mars since 2006 with its six science instruments.

"The ability of MRO to observe for multiple Mars years with a payload
able to see the fine detail of these features has enabled findings such
as these: first identifying the puzzling seasonal streaks and now making
a big step towards explaining what they are," said Rich Zurek, MRO project
scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

For Ojha, the new findings are more proof that the mysterious lines he
first saw darkening Martian slopes five years ago are, indeed, present-day
water.

"When most people talk about water on Mars, they're usually talking about
ancient water or frozen water," he said. "Now we know there's more to
the story. This is the first spectral detection that unambiguously supports
our liquid water-formation hypotheses for RSL."

The discovery is the latest of many breakthroughs by NASA's Mars missions.

"It took multiple spacecraft over several years to solve this mystery,
and now we know there is liquid water on the surface of this cold, desert
planet," said Michael Meyer, lead scientist for NASA's Mars Exploration
Program at the agency's headquarters in Washington. "It seems that the
more we study Mars, the more we learn how life could be supported and
where there are resources to support life in the future."

There are eight co-authors of the Nature Geoscience paper, including Mary
Beth Wilhelm at NASA's Ames Research Center in Moffett Field, California
and Georgia Tech; CRISM Principal Investigator Scott Murchie of the Johns
Hopkins University Applied Physics Laboratory in Laurel, Maryland; and
HiRISE Principal Investigator Alfred McEwen of the University of Arizona
Lunar and Planetary Laboratory in Tucson, Arizona. Others are at Georgia
Tech, the Southwest Research Institute in Boulder, Colorado, and Laboratoire
de Plan?tologie et G?odynamique in Nantes, France.

The agency's Jet Propulsion Laboratory in Pasadena, California, a division
of the California Institute of Technology, manages the Mars Reconnaissance
Orbiter Project for NASA's Science Mission Directorate, Washington. Lockheed
Martin built the orbiter and collaborates with JPL to operate it.

More information about NASA's journey to Mars is available online at:

https://www.nasa.gov/topics/journeytomars

For more information about the Mars Reconnaissance Orbiter, visit:

http://www.nasa.gov/mro


Media Contact

Guy Webster / DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278 / 818-393-9011
guy.w.webster at jpl.nasa.gov. / agle at jpl.nasa.gov

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov

2015-302
Received on Mon 28 Sep 2015 03:55:03 PM PDT