[meteorite-list] Liquid Saltwater is Likely Present on Mars, New Analysis Shows (Phoenix)
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 17 Mar 2009 18:13:33 -0700 (PDT)
Mar. 17, 2009
Liquid saltwater is likely present on Mars, new analysis shows
University of Michigan
ANN ARBOR, Mich. - Salty, liquid water has been detected on a leg of the
Mars Phoenix Lander and therefore could be present at other locations on
the planet, according to analysis by a group of mission scientists led
by a University of Michigan professor. This is the first time liquid
water has been detected and photographed outside the Earth.
Droplets on a leg of the Mars Phoenix lander are seen to darken and
coalesce. Nilton Renno, a professor in the Department of Atmospheric,
Oceanic and Space Sciences says this is evidence that they are made of
liquid water. Credit: NASA/JPL-Caltech/University of Arizona/Max Planck
"A large number of independent physical and thermodynamical evidence
shows that saline water may actually be common on Mars," said Nilton
Renno, a professor in the U-M Department of Atmospheric, Oceanic and
Space Sciences and a co-investigator on the Phoenix mission.
"Liquid water is an essential ingredient for life. This discovery has
important implications to many areas of planetary exploration, including
the habitability of Mars."
Renno will present these findings March 23 at the Lunar and Planetary
Science Conference in Houston.
Previously, scientists believed that water existed on Mars only as ice
or water vapor because of the planet's low temperature and atmospheric
pressure. They thought that ice in the Red Planet's current climate
could sublimate, or vaporize, but they didn't think it could melt.
This analysis shows how that assumption may be incorrect. Temperature
fluctuation in the arctic region of Mars where Phoenix landed and salts
in the soil could create pockets of water too salty to freeze in the
climate of the landing site, Renno says.
Photos of one of the lander's legs show droplets that grew during the
polar summer. Based on the temperature of the leg and the presence of
large amounts of "perchlorate" salts detected in the soil, scientists
believe the droplets were most likely salty liquid water and mud that
splashed on the spacecraft when it touched down. The lander was guided
down by rockets whose exhaust melted the top layer of ice below a thin
sheet of soil.
Some of the mud droplets that splashed on the lander's leg appear to
have grown by absorbing water from the atmosphere, Renno says. Images
suggest that some of the droplets darkened, then moved and
merged - physical evidence that they were liquid.
The wet chemistry lab on Phoenix found evidence of perchlorate salts,
which likely include magnesium and calcium perchlorate hydrates. These
compounds have freezing temperatures of about -90 and -105 Fahrenheit
respectively. The temperature at the landing site ranged from
approximately -5 to -140 Fahrenheit, with a median temperature around
-75 Fahrenheit. Temperatures at the landing site were mostly warmer than
this during the first months of the mission.
Thermodynamic calculations offer additional evidence that salty liquid
water can exist where Phoenix landed and elsewhere on Mars. The
calculations also predicts a droplet growth rate that is consistent with
what was observed. And they show that it is impossible for ice to
sublimate from the cold ground just under the strut of the lander's leg
and be deposited on a warmer strut, a hypothesis that has been suggested.
Certain bacteria on Earth can exist in extremely salty and cold conditions.
"This discovery is the result of the talent and dedication of the entire
Phoenix team and NASA, whose strategy for Mars exploration and the
Phoenix mission is "follow the water," Renno said.
Phoenix landed on Mars on May 25, 2008 and transmitted data back to
Earth until Nov. 10. Scientists are still analyzing the information
The mission was led by NASA's Jet Propulsion Laboratory and the
University of Arizona. Among its preliminary findings, Phoenix verified
that water ice exists in the just beneath the surface of Mars. It sent
back more than 25,000 photos and deployed the first atomic force
microscope ever used outside Earth. The lander was the first Martian
spacecraft to document a mildly alkaline soil and perchlorate salts. It
also observed snow falling from clouds on the Red Planet.
A paper on this research, written by Renno and dozens of his colleagues
on the Phoenix mission, including principal investigator Peter Smith, is
under review at the Journal of Geophysical Research. Other U-M
contributors to this research are Manish Mehta and Jasper Kok, doctoral
students in the Department of Atmospheric, Oceanic and Space Sciences.
The University of Michigan College of Engineering is ranked among the
top engineering schools in the country. At more than $130 million
annually, its engineering research budget is one of largest of any
public university. Michigan Engineering is home to 11 academic
departments and a National Science Foundation Engineering Research
Center. The college plays a leading role in the Michigan Memorial
Phoenix Energy Institute and hosts the world class Lurie Nanofabrication
Facility. For more information, visit: http://www.engin.umich.edu
Mars Phoenix Mission <http://phoenix.lpl.arizona.edu/>
Contact: Nicole Casal Moore <mailto:ncmoore at umich.edu>
Phone: (734) 647-1838
Received on Tue 17 Mar 2009 09:13:33 PM PDT