Mars's Water Could Be Below Surface, Experts Say

Brian Handwerk
for National Geographic News
January 25, 2007
Mars may hold large underground reservoirs of the water and carbon dioxide that once formed the planet's ancient atmosphere, new research suggests.

Stas Barabash and colleagues at the Swedish Institute of Space Physics have studied the Martian atmosphere with data from the European Space Agency's Mars Express orbiter.

The team determined that, of the water and carbon dioxide that once existed on the planet, only a small amount was likely lost to the effects of solar wind over the past 3.5 billion years.

Solar wind is the flow of charged particles that flows briskly from the sun (see a virtual solar system).

Writing tomorrow's issue of the journal Science, Barabash's team suggests that water and carbon dioxide reservoirs may therefore still exist on or below the Martian surface.

Further research into the planet's subsurface and atmosphere could reveal critical information about Mars's climate, they add.

"Knowing [more about the ancient Martian climate], we could speculate whether or not conditions were suitable for any complex structures [like organic materials] to develop.

"The question is thus directly related to the question of Mars's habitability.

"The origin of life, in my opinion, is the most important question the modern science is facing," Barabash said.

Mystery of Missing Water

Ancient Mars was much warmer, and wetter, place than it is today. Geological features indicate that large amounts of liquid water once existed on Mars, yet no one knows what became of them.

(Read related story: "Mars Scientists Intensify Search for Water" [December 15, 2006].)

Three main theories attempt to explain the puzzle.

Some suggest that water and carbon dioxide still exist on Mars in large reservoirs that are as yet unfound—probably below the planet's surface.

Other theories propose that some type of catastrophic cosmic impact removed much of the Martian atmosphere in a single event.

A third suggestion: Solar wind removed Martian water and carbon dioxide.

"I'm a plasma physicist so I really like the last one," said Barabash, a professor of experimental space physics.

"But our last study shows that escape [of water and carbon dioxide] from this channel is not as intense as we thought before, and that's a very big puzzle."

Some scientists caution that much more data is needed to make sense of the findings from Barabash's team.

"Recent measurements both from Mars Express and from Mars Global Surveyor suggest that we have not yet even described all of the loss processes at the present epoch," said Bruce Jakosky, from the Laboratory for Atmospheric and Space Physics at the University of Colorado.

"This means that we cannot yet determine the total loss rate today, let alone be able to extrapolate to earlier epochs."

Barabash also cautions that the solar wind may function in ways that scientists can't yet measure.

"It's possible that solar wind is far more complex than we think," he said. "So we have to explore other escape channels which are also associated with the solar wind."

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