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Extremophiles give clues to alien life – Cosm Feb 05, 2010

Meet the Indestructibles

What nature's own Superheroes can tell us about alien life

We humans are pretty feeble creatures. Take away our clothing, central-heated homes and Bear Grylls, and chances are we’d be dead within a few months from exposure or disease. Toss our fragile spongy bodies into the freezing vacuum of space and, even if we don’t actually explode in a cloud of boiling blood (as the myth goes), without air to breathe and cosmic radiation bombarding our tender flesh, we’d be dead quicker than Katie Price can get married.

But this isn’t true of all Earthlings. As scientists have come to discover, many life-forms have evolved to be extremely hardy and others have evolved to become near-indestrucible. From superheated, deep-sea thermal vents, to pools of flesh-melting acid and even deep within the bowels of the Earth, all over the planet we have found life, not clinging on, but actually thriving in some the most inhospitable environments.

These discoveries have rejuvenated our quest for life elsewhere in the solar system (little green men aside) – and possibly the universe. After all, we can find parallels for these extreme environments in many of the planets and moons we have been able to study – the Jovian moon of Europa, for example, is thought to be home to hydrothermal vents very similar to those that have become oases of extreme life on Earth. We know these creatures are tough but are they tough enough?

To find out, the European Space Agency in 2008 sent 12 boxes containing 664 examples of the best of the best of these so-called extremophiles to the International Space Station. For 18 months, two thirds of the samples sat exposed to the vacuum, massive temperature swings and desiccating conditions of open space. The rest had the luxury of enjoying a thin carbon dioxide atmosphere that simulated the Martian environment.

The samples returned to Earth a few months ago and the first results were published this week. The star of the show turned out to be a humble lichen – lichens are a peculiar partnership of fungus and algae, or cyanobacteria – called Xanthoria elegans. It was able to survive the moisture destroying vacuum and extreme radiation by simply switching off and waiting for conditions to improve. Another of these ‘indestructibles’ is a small, pond-dwelling creature called a tardigrade which can survive temperature swings ranging from -272ºC to +150ºC. There are many more of these super-heroes of the natural world. So let’s meet the ‘indestructibles’.

This week's graphic – Meet the extremophiles - nature's own superheroes

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