Over the years we've heard people warning/lamenting/complaining about Earthlings leaving their junk all over this part of the solar system, whether it's dead satellites floating through space or abandoned equipment left on the surface of the moon or a nearby planet. But now scientists are raising the prospect of us inadvertently transporting to Mars bacteria that is able to survive. Two microbiologists at the University of Florida recently tested some Earth microbes under harsh Mars-like conditions. Here's how Discovery.com's Markus Hammonds describes it:
Wayne Nicholson and Andrew Schuerger ... didn’t choose just any old bacteria, though. The microbes in question were taken from samples of Russian permafrost, collected over 12 meters (40 feet) below ground. These bacteria were first nurtured for 28 days in nutrient-rich dishes kept at normal Earth conditions. Then around 10,000 colonies of the bacteria were subjected to 30 days of conditions intended to mimic Mars, at temperatures of 0°C (32°F) and a pressure of just 7 millibars — the same pressure on the surface of Mars.Six of the bacterial colonies tested, containing a strain known as carnobacterium, managed to grow under these harsh conditions. In fact, surprisingly, the carnobacterium colonies grew better at low pressures and without oxygen than they did under more normal conditions. The reasons why aren’t entirely clear.
As Hammonds points out, six out of 10,000 isn't much. But it's six more than zero. Further, it was "the first time Earth microbes have ever been successfully grown at such a low pressure," he writes. No matter how much we try, it's virtually impossible to guarantee that every piece of equipment we send into space is fully sterilized. Something's going to make it on board (indeed, some have expressed fears that Curiosity Rover may have transported bacteria in its wheels). And its chances of survival in a harsh, alien environment will be exceedingly slim. Except for the mutant strain, of course. Now read this: