[meteorite-list] NASA Research Supports Presence of Large Oceans on Early Mars

[Ron Baalke]

Michael Mewhinney						 June 14, 2007
NASA Ames Research Center, Moffett Field, Calif.
Phone: 650-604-3937
E-mail: mmewhinney at mail.arc.nasa.gov

Robert Sanders
UC Berkeley Office of Media Relations
Phone: 510-643-6998
E-mail: rsanders at berkeley.edu

NEWS RELEASE: 07- 32AR

NASA RESEARCH SUPPORTS PRESENCE OF LARGE OCEANS ON EARLY MARS

MOFFETT FIELD, Calif. - NASA-funded astrobiologists at the University of 
California, Berkeley have discovered evidence supporting the presence of 
large oceans of liquid water on early Mars.

One of the most obvious surface features on Mars is a large plain 
surrounding the north pole that resembles a sediment-filled ocean basin 
with shoreline-like features. But the purported shoreline isn't level, an 
observation that has been used as an argument against the presence of an 
ocean. This new study shows that the undulations can be explained by 
movement of Mars' spin axis, and thus its poles, and that a liquid water 
ocean could indeed have existed there.The scientists' research is scheduled 
to be published in the June 14 issue of Nature magazine.

"This work strongly supports the idea that there were large standing bodies 
of water on the Martian surface," said Carl Pilcher, director of the NASA 
Astrobiology Institute at NASA Ames Research Center, Moffett Field, Calif., 
which co-funded the study. "Interpreting this topography as an ancient 
northern ocean could have a great impact on current and future Mars 
exploration," he added.

"When the spin axis moves relative to the surface, the surface deforms, and 
that is recorded in the shoreline," said study co-author Michael Manga, a 
professor of Earth and planetary science at UC Berkeley, and member of the 
NASA Astrobiology Institute Team there. "On planets like Mars and Earth 
that have an outer shell or lithosphere that behaves elastically, the solid 
surface will deform differently than the sea surface, distorting the 
topography," added primary author Taylor Perron, a former UC Berkeley 
graduate student, now a postdoctoral fellow in Harvard University's 
Department of Earth and Planetary Sciences. Perron's calculations show that 
the resistance of the elastic crust could create elevation variations for 
topographic features like the shoreline, in accord with observations.

Perron, Manga and their colleagues calculate that on Mars, an initial shift 
of 50 degrees from today's pole would be sufficient to disrupt the 
shoreline. Manga theorizes that the shift that precipitated the tilt of 
Mars' rotation axis is related to the presence (and great mass) of an ocean 
at one of the poles. If a flood of water had filled an ocean at the 
northern pole on Mars about 3 billion years ago, its mass might have been 
enough to shift the pole 50 degrees to the south. Once the water 
disappeared, the pole could have shifted back.

Manga also said the source of the water, while unknown, may have produced a 
flood or deluge greater than any that have been observed on Earth, 
evidenced by huge canyons in the flanks of the Tharsis rise, site of the 
solar system's largest volcano.The water may have evaporated, but it may 
also have sunk back into underground dikes, frozen near the surface but 
possibly liquid below.

Additional coauthors of the study include Mark Richards, professor of Earth 
and planetary science and dean of physical sciences at UC Berkeley, Jerry 
Mitrovica from the Department of Physics at the University of Toronto in 
Ontario, Canada, and Isamu Matsuyama from the Department of Terrestrial 
Magnetism at the Carnegie Institution of Washington in Washington, D.C.  
The work is part of UC Berkeley's BioMars project, funded by NASA's 
Astrobiology Institute (http://cips.berkeley.edu/biomars/). The research 
also was supported by UC Berkeley's Miller Institute for Basic Research in 
Science, the Natural Sciences and Engineering Research Council of Canada, 
and the NASA Mars Data Analysis Program.

The NASA Astrobiology Institute (NAI), founded in 1997, is a partnership 
between NASA, 16 major U.S. teams, and six international consortia. NAI's 
goal is to promote, conduct and lead integrated multidisciplinary 
astrobiology research and to train a new generation of astrobiology 
researchers.

For more information about the NASA Astrobiology Institute, visit:

http://nai.nasa.gov/

For information about NASA and agency programs, visit:

http://www.nasa.gov

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