Thursday, November 21, 2013

Have We Already Colonized Mars?

Scientific American reports on a very hardy bacteria discovered by NASA:

High atop a platform inside a clean room at the European Space Agency’s (ESA) launch site in South America, scientists painstakingly searched for microbes near the Ariane 5 rocket due to launch the Herschel space telescope in May 2009. Only very unusual organisms can survive the repeated sterilization procedures in clean rooms, not to mention the severe lack of nutrients available. But the scientists’ careful inspection was fruitful, turning up a type of bacteria that had been seen only once before. Two years earlier this same bug had surfaced 4,000 kilometers away in the clean room at NASA’s Kennedy Space Center in Florida where engineers were preparing the Mars lander Phoenix for launch.

... The researchers named the bacterium Tersicoccus phoenicis. “Tersi” is Latin for clean, as in clean room, and “coccus” comes from Greek and describes the bacterium in this genus’s berrylike shape. “Phoenicis” as the species name pays homage to the Phoenix lander. The scientists determined that T. phoenicis shares less than 95 percent of its genetic sequence with its closest bacterial relative. That fact, combined with the unique molecular composition of its cell wall and other properties, was enough to classify Tersicoccus phoenicis as part of a new genus—the next taxonomic level up from species in the system used to classify biological organisms. The researchers are not sure yet if the bug lives only in clean rooms or survives elsewhere but has simply escaped detection so far, says Christine Moissl-Eichinger of the University of Regensburg in Germany, who identified the species at the ESA’s Guiana Space Center in Kourou, French Guiana.

... Still, researchers would like to know whether such organisms could survive the trip from Earth to Mars, and survive on the Red Planet once they get there. To answer this question, scientists launched spores of the bacteria Bacillus subtilis and B. pumilus to the International Space Station in February 2008 and mounted them outside the orbiting laboratory for a year and a half. The experiment, called PROTECT, subjected the organisms to the vacuum of space, extreme temperature fluctuations and a barrage of radiation. Although many spores died, some survived, proving that certain bugs could successfully hitchhike to Mars. The most damaging effects came from the ultraviolet radiation the spores experienced outside Earth’s protective atmosphere. To survive, “either they have to hide or come up with an ingenious mechanism of repairing the DNA damage,” says Vaishampayan, who worked on the PROTECT experiment.

There is no proof that T. phoenicis actually accompanied Phoenix to Mars, but it is possible. “This genus has surely traveled to Mars already, recently in one or more of our spacecraft—they live comfortably in the clean rooms where we build the craft, right?—and maybe even onboard meteorites millions or billions of years ago,” Fairén says. “Therefore, if these bugs can actually survive on Mars, they must be there already.”

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