for National Geographic News
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].)
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