Find gives hope for life on Mars

By SIMON COLLINS in DUNEDIN

A lichen which may one day be used to plant life on Mars has been found growing inside rocks near the South Pole.

Waikato University biologist Professor Allan Green told the NZ Antarctic Conference in Dunedin this week that an international team of scientists was amazed to find 15 species of lichens in a small rock outcrop on Mt Kyffin, 750km south of Scott Base.

Eight species were found in the Taylor Valley, a "dry valley" west of Scott Base which has received virtually no rain for millions of years.

One species, a primitive endolithic (rock-penetrating) lichen called chroococcidiopsis, has been nominated by some US experts as the best candidate for planting life on Mars because it can grow in the most extreme environments, from cold mountains to hot springs.

"It will grow anywhere where there are bare rock surfaces," said Professor Green.

As long as there is nothing growing above it to trap sunlight, the lichen can use the tiny fraction of light that penetrates rock to transform the sun's energy into chlorophyll, just like a plant above ground.

Like other plants, it generates oxygen in the process. On Mars, it could begin to create an atmosphere that could eventually contain enough oxygen to support higher life forms.

On Earth, single-celled organisms such as chroococcidiopsis and later more complex plants have taken about 2 billion years to gradually raise the proportion of oxygen in the air from zero to the current 20 per cent.

On Mars, scientists believe they could do it much more quickly. Dr Imre Friedmann, a microbiologist at Nasa who has been the main proponent of using chroococcidiopsis, has suggested genetically modifying the organism to do the job faster.

However, he has also described his proposal as a mere "thought experiment". "I don't think any of us alive today will see it happen," he has said.

Professor Green said the expedition to Mt Kyffin was high-risk. The Canadian pilot who flew the team in from McMurdo Airfield flew around for an hour before he found a place where he was willing to risk landing - about 8km away from the rock outcrop they wanted to visit. The scientists had to ski across country then climb the mountain to get to the exposed rocks.

"They were shattered," he said.

Expedition leader Brian Staite, an experienced climber with Antarctica NZ, refused to let the scientists climb to the exact position where an earlier NZ Alpine Club group first saw lichen in 1959-60, because it was too dangerous.

But the group - hand-picked by Professor Green as the world's top experts in their fields - were still astonished by the variety of lichens they found at both study sites.

The expert on endolithic lichens, Professor Burkhard Buedel from Germany's Kaiserslautern University, was "blown away by the endolithic community" in the Taylor Valley.

"He started hitting rocks and every time he found lichen," said Professor Green.

At Mt Kyffin, the 15 lichen species included five never found in Antarctica before.

In his talk at the conference, Professor Green quoted an unnamed reviewer of his application to Antarctica NZ for support for the expedition who asked why a person of his talents was "still going around collecting the names of things at various places".

"The answer is: We don't actually know what's there," he said.

"Old-fashioned look-and-seeing is still a priority if we're going to make any global interpretations."

He plans to propose the Mt Kyffin outcrop should become protected, at least until scientists have a chance to see whether there are any other places in the area with similar biodiversity.

www.astrobiology.com/terraforming.html
http://cber.bio.waikato.ac.nz