tardigrades (water bears) from Goldstein Lab on Vimeo.

The creatures above are amongst some of the oddest on the planet. They're tardigrades, also known as water bears. They can survive being deep frozen, boiled, subjected to extreme pressure and even being exposed to what, for any other animal, would be lethal doses of radiation. The day a vague but catastrophic disaster comes and wipes out the human race could still be the day the water bears have their picnic.

They're currently in the news because of an experiment to see how hardy they are: Tardigrades survive exposure to space in low Earth orbit. This was conducted by the Tardigrades in Space (TARDIS) project. What they did was send up two species of tardigrade, Richtersius coronifer and Milnesium tardigradum. They then exposed samples of each species to the vacuum of space, while others were exposed to the vacuum and various types of radiation. What they found that when it was protected from solar radiation M. tardigradum was as happy as normal. When the sample returned it reproduced as well as the control sample left on Earth.

It's an experiment with serious implications for astrobiology. One is that it reminds physicists that life is a lot weirder than they realise, which has implications for any astrobiologists who still want to insist on a 'habitable zone'. The other is that quite complex creatures can be shown to be able to survive in space. We know that Earth receives Martian meteorites, and it's reasonle to assume that Mars has been hit by rocks from Earth. It's possible that the two planets could have been exchanging life and there may be Martians for visiting astronauts to find. They're unlikely to be tardigrades, as there's no evidence of tardigrade food on Mars, but microbes remain a possibility. It's not just about exobiology though. Seeing how the tardigrade can protect itself could also have medical implications too.

You can read more about this at Nature, Science and New Scientist.