Associated Press
WASHINGTON — Mars is now dry, dusty and cold, but a new study confirms that the Red Planet once was covered by vast oceans and had more water per square mile than Earth.
In fact, it once had enough water to cover the planet to a depth of almost a mile, researchers say, citing an analysis of data measuring the amount of molecular hydrogen in the atmosphere.
Unlike Earth, Mars lost its water over millions of years through a combination of chemical reaction and the bombardment of asteroids and comets.
There is much evidence now that Mars had an ocean of liquid water, said Vladimir Krasnopolsky of Catholic University of America. "But the climate changed. … Mars became a cold desert."
Krasnopolsky said the proven abundance of water in Mars’ early history "improves the prospects" that life could have evolved there.
In a study appearing today in the journal Science, planetary researchers Krasnopolsky and Paul Feldman of Johns Hopkins University said Mars’ upper atmosphere contains molecular hydrogen, or H2, a finding that confirms earlier theoretical models of the water history of the planet.
The H2 comes from a chemical reaction called dissociation that split the hydrogen from water, H20, and allowed the lighter hydrogen to escape to the atmosphere.
"It is a complex chemistry process of which we are detecting only one piece," the molecular hydrogen, said Feldman. But these findings help to support earlier estimates of the amount of water once on Mars.
Krasnopolsky said there still is water on Mars, but it is either liquid deep in the soil or ice. He estimated that the Martian polar ice caps contain enough water to flood the planet to an average depth of about 45 feet.
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