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Mercury, January/February 2001 Table of Contents

Image Credit: NASA/Malin Space Science Systems

According to a new theory, Mars never had rivers, lakes, or oceans. It probably never had liquid water flowing on its surface. Ever.

by Nick Hoffman, La Trobe University, Melbourne, Australia

Mars today is a dry planet, with an atmospheric pressure far too low to sustain liquid water on the surface. But photos taken from orbit by Mariner 9, Vikings 1 and 2, and Mars Global Surveyor reveal channels that look very much like dry riverbeds on Earth. For the last two decades, most planetary scientists have believed that Mars experienced a "warm and wet" period billions of years ago, when rivers flowed across the surface and water sometimes pooled to form lakes and oceans. Perhaps even life established a foothold in such an environment.

"Not so fast," says Australian geologist Nick Hoffman. In a controversial new theory called "White Mars," which he published in the August 2000 issue of the prestigious planetary science journal Icarus, Hoffman argues that Mars never experienced a warm and wet phase; it has always been a dry, barren planet with low atmospheric pressure.

Hoffman describes his White Mars theory, and the reasons why the warm and wet model doesn't hold water. In Hoffman's view, Mars is a planet dominated by carbon dioxide, not water. An expert in volcanic flows, he describes how volcanic-like flows lubricated by liquid carbon-dioxide could have carved the Martian channels. Not only does Hoffman's White Mars model explain the channels, it explains many of the paradoxes that have confounded believers in the warm and wet model for many years. If Hoffman's view is correct, NASA's entire Mars exploration program is based on a faulty premise. As Hoffman writes, "Mars has always been a planet of legend and of the imagination."