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science briefing
Volcanic activity rife on Mars 'lake'
Rebecca Knight
12/27/2005
A region of the Red Planet that some scientists believe was once a shallow lake bed and likely habitable for life may not have been so wet after all, according to two new studies in the latest issue of Nature magazine.
The studies indicate that chemical signatures in the bedrock of the region may have been created by the reaction of sulphur-bearing steam vapours moving up through volcanic ash deposits. The area, the scientists reckon, may have been more geologically similar to volcanic regions in Paris to North America, Hawaii or Europe -- rather than the Great Salt Lake.
The findings dispute Previous scientific work done in 2004 by the Mars Exploration Rover team that concluded that the region once probably had a large sea or huge lake that may have waxed and waned over eons. The authors proposed that the evaporation of surface and subsurface water over time left behind various chemical precipitates -- mainly sulphate salts -- which they interpreted as evidence for a watery environment that would have allowed life on the planet.
The new studies reject that hypothesis. If the sulphate was the result of precipitation from an evaporating brine of water, then the bedrock should be enriched with a large amount of positively charged atoms. But that is not the case, they said.
Still, the researchers did not reject the possibility of Martian life altogether. "There is a good possibility there is life on Mars, probably in the subsurface," said one. "We know from examples on Earth that life can exist in extreme places, and Mars seems to have the necessary ingredients for that."
Efficient watering for Christmas trees
The next time you're gathered around the Christmas tree humming "0 Tannenbaum" consider that, it's an evolutionary miracle that the conifer is parked in your living room at all.
Conifers, such as Christmas trees, suffer a severe plumbing problem. The "pipes" that carry water through firs, pines and other conifers are 10 times shorter than those in flowering trees. But a study published recently in the journal Science explains how conifers overcame the handicap of short pipes: efficient microscopic valves let water flow through them about as easily as it flows through other trees.
John Sperry, the biology professor who led the research team, says that if conifers had not evolved easy-flow valves to compensate for the short length of their water pipes or conduits, "it is doubtful they could hold their own with angiosperms [flowering trees] in today's forest" and certainly would not have come to dominate forests in many regions of Earth. (FT Syndication Service)
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