Sept. 3, 2003 — Laboratory evidence is challenging theories that Mars' ruddy surface came from a past when the planet was awash with water, New Scientist said.
Defenders of this hypothesis say Mars' reddish dust came from iron in rocks that over billions of years dissolved into the planet's oceans, lakes and rivers.
The iron oxidized and was then deposited all over the Martian surface thanks to the planet's weather system. It was then left high and dry after the waters mysteriously disappeared, either receding below ground or boiling into space.
But U.S. scientist Albert Yen of NASA's Jet Propulsion Laboratory has assailed this idea, noting a strange discrepancy between Mars' dusty topsoil and its rocks.
The topsoil has more magnesium and iron than the rocks, according to data sent back by the 1997 Mars Pathfinder mission.
Yen believes that the dust can only have come from tiny metal-rich debris that constantly falls onto Mars from space.
According to his calculations, the dust-fall is big enough to coat Mars to a depth of two inches every billion years.