Meteorite Data Suggests Water on Mars : Science: Evidence trapped in rock samples blasted to Earth offer the possibility that it was a warm, wet and rainy planet in its early days.

New scientific data carried to Earth aboard rocks blasted off Mars by meteors suggests that liquid water may exist beneath the planet’s surface, a finding that could bolster the plausibility of life there in the not-too-distant past.

Conventional wisdom held that water could exist in the planet’s dry, cold climate only as vapor or frozen into permafrost. But in today’s issue of the journal Nature, University of Michigan planetary scientist Thomas M. Donahue concludes that liquid water probably still lurks in rocks in the Martian crust.

“That’s very big news,” said Matthew Golombeck, a planetary scientist at the Jet Propulsion Laboratory in Pasadena.

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Further, Donahue’s calculations show that a very early Mars was a warm, wet, rainy planet, quite conducive to the kind of biological evolution that occurred on Earth.

Scientists and laypeople alike have long speculated about life on the red planet.

Telescopes had seen systems of canals on the planet that could have been constructed by alien beings, or at the least formed by rapidly flowing rivers such as those on Earth.

But those visions were brought to an abrupt end when the Viking missions sent to Mars 20 years ago to look for signs of life came up with nothing but handfuls of dust. Mars was frigid, barren and inhospitable to life. What had seemed to be vegetation turned out to be nothing but rocks. If rivers had carved out canals, they had long since dried up.

Mars watchers were disappointed again in 1993 when NASA’s billion-dollar Mars probe Observer lost radio contact with Earth just as it was about to coast into Martian orbit. With Observer lost in space, prospects of new findings from Mars any time soon seemed to dim.

Now rock samples from Mars have fallen from the sky into scientists’ laps in the form of meteorites found at various places around the Earth. “It’s like having a sample returned without having to pay for it,” Golombeck said.

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The rocks in question are known as SNC meteorites, chunks of mineral-laden material that researchers believe are certainly from Mars because the gas trapped inside the meteor is identical to the unique Martian atmosphere, Donahue explained. As the minerals formed, perhaps a billion years ago, water became attached to the growing crystals.

Last year, Caltech graduate student Laurie Leshin Watson, who is now at UCLA, published a paper in the journal Science that concluded that the type of water locked in the rock samples is the same as the water vapor present today in Mars’ atmosphere.

On Earth, hydrogen in everyday water contains a single proton. The hydrogen in “heavy water,” a rarer form also found on Earth, contains a proton and a neutron.

On Mars, atmospheric hydrogen analyzed by telescopes was found to be five times richer in heavy hydrogen than on Earth, a surprise since Earth and Mars presumably condensed from the same cosmic cloud about the same time.

Leshin Watson found that the water in the Martian rocks contains the same proportion of heavy hydrogen as the water in Mars’ thin atmosphere. This means there must be some type of water exchange between the atmosphere and the ground. Such chemical transfer cannot take place unless the ground water is in liquid form, scientists said.

Since lighter hydrogen would tend to float away from the thin Martian atmosphere, the unchanging ratio over time suggests that ancient Mars contained huge reservoirs of water, perhaps to an average depth of several meters.

“The shocker for me was that the ratio (of heavy to light water) has scarcely changed in the past billion years,” Donahue said. “The amount of water in the crustal reservoir has to be very large compared to the amount that’s escaped.”

Researchers still do not know how Mars could ever have been warm enough to support huge rivers and vast flooded plains. The ancient sun was dimmer than today, and Mars is more distant from our local star than Earth.

As for the possibility of life, it’s currently quite remote, but not impossible. “Conditions are still very harsh,” Donahue said.

A planned Mars Pathfinder lander, due to be launched next year, might bring back more answers. “If it lands next to a Martian,” Golombeck said, “we’ll be able to tell what it’s made of.”