According to Shkaplerov, during spacewalks from the ISS under the Russian program, the cosmonauts took samples with cotton swabs from the station’s external surface. In particular, they took probes from places where the accumulation of fuel wastes were discharged during the engines’ operation or at places where the station’s surface is more obscure. After that, the samples were sent back to Earth.
"And now it turns out that somehow these swabs reveal bacteria that were absent during the launch of the ISS module. That is, they have come from outer space and settled along the external surface. They are being studied so far and it seems that they pose no danger," the Russian astronaut said.
Some terrestrial bacteria also survived on the space station’s external surface, though had remained within a space vacuum for three years. In addition, the bacteria underwent sharp swings in temperature from minus 150 to plus 150 degrees Celsius.
The bacteria were brought to the space station accidentally on tablet PCs together with various materials that are placed aboard the ISS for long periods to study the materials’ behavior in outer space.
TASS. (2017) Scientists find living bacteria from outer space on ISS satellite's surface. [online] Available at: http://tass.com/science/977591 [Accessed 28 Nov. 2017]
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