NZ fossils give pointer to Martian life forms

By SIMON COLLINS

A $500,000 research project led by Auckland University geologist Kathy Campbell is tracing, for the first time, a complete sequence of how microbes in hot springs eventually turn into fossils in quartz rock of the kind that may be found on Mars.

Two US Rover spacecraft, which landed on the planet in January, are examining its rocks looking for the same kind of telltale signs of fossilised life that Dr Campbell's team has found in New Zealand.

Although the spacecraft have not found definite fossils, they have proved that Mars once had the key requirement for life - liquid water.

"Our whole concept of what's going on on Mars has changed so radically because we are actually on the ground instead of orbiting," said Dr Campbell. "I'm cautiously optimistic that life may have existed on Mars because there is so much evidence of water everywhere."

Dr Campbell, 41, was born near San Francisco and worked on the search for extraterrestrial life for Nasa (the US National Aeronautic and Space Administration) before taking a lectureship at Auckland in 1997. She will give a public lecture on the latest data from Mars tonight.

Dr Campbell said New Zealand had the Earth's most complete record of hot-spring microbes "from slime to quartz" - from living microbes in Taupo hot pools to fossilised remains of the same microbes that lived in ancient hot pools on the Coromandel Peninsula and in undersea sediments near Gisborne, which have now been lifted up into mountains.

"From a geologist's point of view, New Zealand is one of the most famous geological locations in the world. It is exciting and active," she said.

"We are saying, let's run the video. Let's go to 1000-year-old hot spring deposits, then to 10,000-year-old deposits and 200,000-year-old deposits and 5 million-year-old deposits, and see how the signature of the microbes changed ...

"If they find hot-spring deposits on Mars, which they think are there, it's likely the stuff will be very old. We can then figure out if there is a biological signal there."

If life did exist on Mars, Dr Campbell said, it certainly was nothing as complex as the plants and animals that have evolved on Earth. Mars has never developed the shelterbelt of oxygen-rich air that plants have generated here.

"Its atmosphere is thin and made up mostly of carbon dioxide.

"If life is there now, it is probably in the ice or in the subsurface beneath the soil, because the ultraviolet radiation in the thin atmosphere would kill any Earth-like life, even microbial life - it would fry it. So there is not going to be any slime growing on a rock.

"But we have microbes 3.5km deep and in ice here on Earth, so if we could drill into Mars there may be deep subsurface microbes there today." Even the deep underground microbes on Earth still depend on tiny pockets of water trapped in cracks in the rocks.

" ... It's the basic building block of amino acids made up of hydrogen, carbon, nitrogen and oxygen," Dr Campbell said.

The Rover mission has found landforms, such as tiny rounded rocks of iron oxide, that are known from Earth to be caused by running water. So liquid water once existed there, but possibly only billions of years ago when the planets were still young and warm from the energy generated when particles in space came together to form them.

From Taupo to Mars

* Microbes in hot springs eventually turn into fossils in quartz rock.

* New Zealand has examples of the entire process, from living microbes in Taupo hot pools to fossilised remains on the Coromandel Peninsula and near Gisborne.

* Scientists can compare these specimens if similar telltale signs of fossilised life are found in Mars rocks.

* Any life-forms on Mars are probably in the ice or in the subsurface, away from lethal ultraviolet radiation in the thin atmosphere.

* Hardy microbes living inside Taupo hot springs are providing clues for American scientists searching for life on Mars.

* Dr Campbell speaks about life on Mars in the Apec Room, Auckland Museum, at 7.30pm tonight.

Unseen Worlds - lecture series