Now a radical new Australian theory about the evolution of Mars suggests the planet may have always been a frozen wasteland devoid of life.

University of Melbourne geologist Dr. Nick Hoffman has evidence that is forcing these scientists to reassess their long-held beliefs about how Mars formed and whether there is, or ever has been, liquid water and life on the surface of Mars.

Dr. Hoffman has studied erosional features scarring the surface of Mars such as valleys, channels and gullies. He suggests that liquid and gaseous carbon dioxide (CO2) could be responsible for gouging out these features, not water, as believed by the majority of scientists.

NASA is looking for life on Mars based on the theory that liquid water once existed on the surface of Mars. If Dr. Hoffman’s theory proves correct, their search will be futile as they will have been searching in the wrong places and in the wrong way.

“We need to think more clearly about where life would be on Mars and how we could collect samples. If there is life on Mars it is likely to be many kilometers underground. By finding where water isn’t, you narrow down the sites worth looking for liquid water, and hence, life,” says Dr. Hoffman.

Dr. Hoffman and colleagues from the US Geological Survey (USGS) presented their most recent evidence in the latest Geophysical Research Letters.

Their research focused on gullies formed by areas of collapsed terrain along the rim of the 3.5 billion year old Hellas basin, an impact crater 2,000 kilometers wide and 9 kilometers deep.

Their data suggests that the gullies were scoured by debris helped along by flowing liquid and gaseous CO2 rather than hot springs or exploding groundwater as originally proposed.

Hoffman believes the Hellas Basin Gullies formed when volcanic magma mixed with trapped and compressed frozen carbon dioxide. This expanded violently, causing the ground to collapse and flow down the slope, gouging out a gully as it went. The now liquid and gaseous carbon dioxide acted as a lubricant for the debris to continue flowing.

Dr. Hoffman has also studied much younger gullies that may be still forming today or that formed within the last 10,000 years.

“Previous researchers have speculated that because of the frosty sub-zero temperatures around the location of the gullies, they must have been formed by hot groundwater or springs bursting through the surface. The presence of water would have also boosted their theory of the possibility of life on Mars,” says Dr. Hoffman.

“Data from my own observations of the gullies suggest that the flows, which occur each Mars Spring, occur by thawing of CO2 snow cover at a time when there was still solid CO2 (dry ice) on the surface and the ground temperature is around -130 degrees celcius,” he says.

“You cannot get anything water-based to flow at those temperatures. Even the most caustic cocktail we could make to lower the freezing point of water would fail to flow.

“But our modeling reveals it is possible to make a flow with the lubrication of gaseous CO2. As the carbon dioxide snow boils off, the gas would act like millions of tiny hovercraft transporting the rocky debris down the slope. Frozen carbon dioxide mixed with the debris could continue to boil off as the debris ploughed downwards, prolonging the flow.”

“Initially, planetary scientists deemed my theory impossible, but they appreciated the existence of an alternative view,” he says. “With this recent evidence, however, they now see the idea as possible and are starting to look at the data in detail.

“The ideas about liquid water on Mars arose nearly 30 years ago when the first Martian probes sent back images showing vast networks of channels, valleys and gullies.

“The space shuttle program then swallowed up any spare funding available for further research into the planets, so the theory of water on Mars just sat there.

“A whole new generation of scientists has grown up believing there is water on Mars because there was no other idea around. I have upset supporters of the water-based model by showing there is another idea that fits the data.

“In attempting to explain the flood channels as evidence of liquid water, planetary scientists have developed a host of concepts and models that are generally unworkable, often impossible, and collectively raise more problems than they solve."

Hoffman has consolidated his ideas into a model he calls "White Mars."

"‘White Mars’ brings together a broad range of observations and knowledge of flow processes to explain Mars in a single, simple, non-paradoxical model,” he says.

[Contact: Dr. Nick Hoffman, Jason Major]

27-Mar-2002