Monday, March 8, 2010

Searching for alien life in California's Mono Lake



Mono Lake has a bizarre, extraterrestrial beauty. Just east of Yosemite National Park in California, the ancient lake covers about 65 square miles. Above its surface rise the twisted shapes of tufa, formed when freshwater springs bubble up through the alkaline waters.

Felisa Wolfe-Simon, a geobiologist, is interested in the lake not for its scenery but because it may be harbouring alien life forms, or “weird life”. Mono Lake, a basin with no outlet, has built up over many millennia one of the highest natural concentrations of arsenic on Earth. Dr Wolfe-Simon is investigating whether, in the mud around the lake or in the water, there exist microbes whose biological make-up is so fundamentally different from that of any known life on Earth that it may provide proof of a shadow biosphere, a second genesis for life on this planet.

Arsenic is chemically close to phosphorus. While phosphorus is a primary building block of life on Earth — an essential component of DNA and ATP, the energy molecule — arsenic is a deadly poison. In Mono Lake there are micro-organisms that live with arsenic. But they don’t incorporate it into their biology.

Dr Wolfe-Simon has theorised that there may be life that chose an “evolutionary pathway” to utilise arsenic. If such microbes existed, it could suggest that life started on our planet not once but at least twice. In turn this would help to support the idea that life is much more likely to have started elsewhere in the galaxy.

“There is life ‘as we know it’ and there is life ‘as we don’t know it’. What would that look like? I am trying to give us a framework to work with to help us look for what ‘we don’t know’, the particular framework of arsenic,” she says.

Dr Wolfe-Simon has taken samples from the mud and the waters of the lake and is performing a series of multiple dilutions — hugely increasing the levels of arsenic and reducing residual phosphorous to zero. She adds sugar, vitamins and other nutrients to encourage organisms to grow and tests the results.

Her experiments are not yet over but she is quietly pleased with the progress she is making. “We have some very exciting data,” she says. The results should be published by the end of this year.

She points out that Mono Lake arsenic life, if found, may only go as far as proving the extreme adaptability of life on Earth billions of years ago. It is generally agreed that on early Earth the chemical soup was very different because of the material being thrown out of the planet’s depths by volcanoes and hydrothermal vents and the lack of biologically derived oxygen. If arsenic was around in far greater concentrations then, perhaps “arsenolife”, as she calls it, in Mono Lake is evidence of that ancestral life, a finding that would deepen our understanding of how life on Earth got started.

But she hopes that her research may help scientists to reconsider what alien or “weird” life might look like: “It may prove that there are other possibilities that are beyond our imagination. It opens the door for us to think about biology in ways we have never thought. We are going to look for life on other planets and we only know to look for that which we know. This may help us to develop tools to look for something we have never seen.”

Her work is funded by the Nasa Astrobiology Institute and she is based at the laboratories of Professor Ron Oremland, of the US Geological Survey in Menlo Park, California. Does she believe that there are alien life forms out there? “I don’t know how there could not be extraterrestrial life,” she replies.

Original story can be found here.

0 comments: