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

[Ron Baalke]

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