Weird Alien Life on Earth - And Earth Microbes on Alien Planets

Cartoon by Gaspirtz

In a study examining whether terrestrial bacteria could survive on Mars, scientists from Princeton University, the Kennedy Space Center, and Michigan State University, exposed a bacterium (Psychrobacter cryohalolentis), originally isolated from Siberian permafrost here on Earth, to harsh conditions like those on Mars -- low temperatures and atmospheric pressures, and extreme dryness and ultraviolet (UV) irradiation flux. Though certain terrestrial microbes might pose a significant contamination threat on Mars, the researchers reported their bacterium could not survive the UV levels typically found on the martian surface.

So what about beneath the surface? Another article describes exposure of Arctic bacteria to simulated martian conditions, including UV irradiation equivalent to about 80 days on the surface of Mars, freeze-thaw cycles, low pressure, and comparable atmospheric gas composition. In the report, scientists from the University of Aarhus in Denmark say that even a 2-centimeter layer of dust provided significant protection to bacteria, and that they were better able to survive at even greater depths. Bacterial DNA and proteins were more resistant to destruction than the bacteria themselves. So it appears that all an Earth microbe would have to do to survive on Mars would be to dig in for the duration.

"Investigators focusing on the survival potential of Earth's extremophiles on Mars provide important baseline studies relevant to planetary exploration," says Sherry L. Cady, editor of Astrobiology. "The potential for forward contamination during the exploration of another planetary body is a global concern of all space-faring nations."

Astrobiologists recognize that potential life forms may be very different from the types of living organisms we are used to seeing on Earth. In a separate article entitled, "Signatures of a Shadow Biosphere," the authors explain how the search for weird alien life (life as we do not know it) can begin right here on Earth. "Alternative biochemistries may escape our current efforts tailored to characterize and identify known life," says co-author Felisa Wolfe-Simon of Harvard University. An organism of extraterrestrial origin identified here on Earth, she says, might "suggest either a deep root to known biology or perhaps even a 'second genesis' of life."

Perhaps the thing from outer space is living right next door to you and you just haven't realized it yet.