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No water for 4bn years on Mars
22/07/2005 11:27 - (SA)
Washington - A study of Martian meteorites shows the surface of the red planet probably has not had significant amounts of free-standing liquid water for the last four billion years, according to a study published on Thursday in the United States.
The meteorites indicate the planet's surface temperature has not risen significantly above zero degrees Celsius in that period, making the existence of large bodies of water unlikely, said researchers David Shuster of the California Institute of Technology and Benjamin Weiss of the Massachusetts Institute of Technology.
Their conclusion leaves unanswered the reason for Mars' many geological features which suggest the former presence of water, like deep gorges, dry river beds and sediment deposits.
Many planetologists believe, during one epoch, the temperature on Mars was sufficiently warm to allow large bodies of water to form on the surface, shaping much of the landscape.
Putting the research into context
"Our research doesn't mean there weren't pockets of isolated water in geothermal springs for long periods of time, but suggests instead there haven't been large areas of free-standing water for four billion years," said Shuster.
"Our results seem to imply that surface features indicating the presence and flow of liquid water formed over relatively short time periods," he said.
The two scientists examined a class of Martian meteorites called nakhlites for the diffusion of argon, a highly temperature-dependent element, in the minerals in the meteorites.
The results showed the meteorites could not have been heated to more than zero degrees Celsius since the meteorites crystallised, which the scientists put between two billion and four billion years ago.
They concluded that the top several kilometres of the crust of Mars has not been significantly warmer during the long period than it is today.
- AFP
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