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

[Ron Baalke]

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 Planétologie et Géodynamique 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