[meteorite-list] NASA Research Suggests Mars Once Had More Water than Earth's Arctic Ocean

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 5 Mar 2015 16:36:01 -0800 (PST)
Message-ID: <201503060036.t260a1YB010125_at_zagami.jpl.nasa.gov>

March 5, 2015
     
NASA Research Suggests Mars Once Had More Water than Earth's Arctic Ocean

A primitive ocean on Mars held more water than Earth's Arctic Ocean,
according to NASA scientists who, using ground-based observatories, measured
water signatures in the Red Planet's atmosphere.

Scientists have been searching for answers to why this vast water supply left
the surface. Details of the observations and computations appear in
Thursday's edition of Science magazine.

"Our study provides a solid estimate of how much water Mars once had, by
determining how much water was lost to space," said Geronimo Villanueva, a
scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and
lead author of the new paper. "With this work, we can better understand the
history of water on Mars."

Perhaps about 4.3 billion years ago, Mars would have had enough water to
cover its entire surface in a liquid layer about 450 feet (137 meters) deep.
More likely, the water would have formed an ocean occupying almost half of
Mars' northern hemisphere, in some regions reaching depths greater than a
mile (1.6 kilometers).

The new estimate is based on detailed observations made at the European
Southern Observatory's Very Large Telescope in Chile, and the W.M. Keck
Observatory and NASA Infrared Telescope Facility in Hawaii. With these
powerful instruments, the researchers distinguished the chemical signatures
of two slightly different forms of water in Mars' atmosphere. One is the
familiar H2O. The other is HDO, a naturally occurring variation in which one
hydrogen is replaced by a heavier form, called deuterium.

By comparing the ratio of HDO to H2O in water on Mars today and comparing it
with the ratio in water trapped in a Mars meteorite dating from about 4.5
billion years ago, scientists can measure the subsequent atmospheric changes
and determine how much water has escaped into space.

The team mapped H2O and HDO levels several times over nearly six years, which
is equal to approximately three Martian years. The resulting data produced
global snapshots of each compound, as well as their ratio. These
first-of-their-kind maps reveal regional variations called microclimates and
seasonal changes, even though modern Mars is essentially a desert.

The research team was especially interested in regions near Mars' north and
south poles, because the polar ice caps hold the planet's largest known
water reservoir. The water stored there is thought to capture the evolution
of Mars' water during the wet Noachian period, which ended about 3.7
billion years ago, to the present.

>From the measurements of atmospheric water in the near-polar region, the
researchers determined the enrichment, or relative amounts of the two types
of water, in the planet's permanent ice caps. The enrichment of the ice
caps told them how much water Mars must have lost - a volume 6.5 times
larger than the volume in the polar caps now. That means the volume of
Mars' early ocean must have been at least 20 million cubic kilometers (5
million cubic miles).

Based on the surface of Mars today, a likely location for this water would be
in the Northern Plains, considered a good candidate because of the low-lying
ground. An ancient ocean there would have covered 19 percent of the
planet's surface. By comparison, the Atlantic Ocean occupies 17 percent of
Earth's surface.

"With Mars losing that much water, the planet was very likely wet for a
longer period of time than was previously thought, suggesting it might have
been habitable for longer," said Michael Mumma, a senior scientist at
Goddard and the second author on the paper.

NASA is studying Mars with a host of spacecraft and rovers under the
agency's Mars Exploration Program, including the Opportunity and Curiosity
rovers, Odyssey and Mars Reconnaissance Orbiter spacecraft, and the MAVEN
orbiter, which arrived at the Red Planet in September 2014 to study the
planet's upper atmosphere.

In 2016, a Mars lander mission called InSight will launch to take a first
look into the deep interior of Mars. The agency also is participating in
ESA's (European Space Agency) 2016 and 2018 ExoMars missions, including
providing telecommunication radios to ESA's 2016 orbiter and a critical
element of the astrobiology instrument on the 2018 ExoMars rover. NASA's
next rover, heading to Mars in 2020, will carry instruments to conduct
unprecedented science and exploration technology investigations on the Red
Planet.

NASA's Mars Exploration Program seeks to characterize and understand Mars
as a dynamic system, including its present and past environment, climate
cycles, geology and biological potential. In parallel, NASA is developing the
human spaceflight capabilities needed for future round-trip missions to Mars
in the 2030s.

To view a video of this finding, visit:

http://youtu.be/WH8kHncLZwM

More information about NASA's Mars programs is online at:

http://www.nasa.gov/mars

-end-

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Nancy Neal Jones/Elizabeth Zubritsky
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039 / 301-614-5438
nancy.n.jones at nasa.gov / elizabeth.a.zubritsky at nasa.gov
Received on Thu 05 Mar 2015 07:36:01 PM PST