junio 02, 2005

Earth bacteria could invade Mars

Earth bacteria could invade Mars

By Lucy Sherriff
Published Thursday 2nd June 2005 12:47 GMT
Earth-bugs might just be able to survive on Mars, according to new research, although the circumstances do have to be perfect.

The research team from the University of Florida warns that at least one type of earthly bacteria could survive long enough to hitch a ride to the red planet, and leave a biological signature in the Martian soil. Any future missions hunting for life on Mars will need to take care to distinguish between Martian life, and any possible alien invaders, the researchers say.

The general consensus is that the hard UV exposure on Mars would be sufficient to kill most forms of Earth bacteria. In fact laboratory tests show that five minutes of exposure to ultra-violet light at Martian levels is enough to kill even the most resilient of bacterial species: the blue-green algae Chroococcidiopsis sp. 029.

But if the bacteria is protected by just one millimetre of Martian soil, it could survive for at least 24 hours. If the conditions are just right, the bacteria could even grow, although this is much less likely. The Martian environment is quite horrible for Earth life, and the low temperatures, low pressures and aridity do not make for comfy conditions.

The study also found that signs of life, such as Chlorophyll and some enzyme activity, will persist for hours, and perhaps much longer, after the bacteria have died. Since the search for life on Mars will look for these very indicators, mission planners will have to gather other supporting evidence for life, if they are to be sure of what they have found.