A routine wipe-down of the exterior of the International Space Station revealed that plankton had not only found its way onto the research vessel, but was alive despite direct contact with the vacuum of space. 

The discovery was revealed Tuesday by Russian scientists working with the ISS program. As part of a spacewalk involving the launch of nanosatellites, cosmonauts Olek Artemyev and Alexander Skvortsov were instructed to clean the windows of the station, called illuminators. Despite being 225 miles above the Earth's surface, the ISS can get coated with material such as micro-meteors, space junk, and residue from its own engines.

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Also routine is the examination of the wipes, leading to the plankton discovery. 

"Results of the experiment are absolutely unique. We have found traces of sea plankton and microscopic particles on the illuminator surface. This should be studied further," chief of the Russian ISS orbital mission, Vladimir Solovyev, told Russia's ITAR-Tass news agency.

But even Solovyev was at a loss as to exactly how the micro-organisms made the trip. Plankton can be easily differentiated by their shape, and the kind found on the ISS are not native to the region of the Baikonur Cosmodrome in the Central Asian nation of Kazakhstan, the launch site servicing the station. It is unlikely the ISS got its extra passengers as the result of an incoming vehicle.

This led to the theory that the microscopic sea creatures were in fact blown to the ISS via high-altitude air currents rising from Earth.

To complex life forms such as humans or plants, space is one of the most hostile environments known. There is no oxygen to breath, no water to drink, no air pressure or gravity to stop cells from expanding and exploding. Radiation, in the form of highly charged particles emanating from the Sun as solar wind, saturates the solar system in every direction. Powerful cosmic rays, which can destroy DNA at a molecular level, blast in from interstellar space. Temperatures range from cold so deep that electrons whizzing around their atomic nuclei begin to slow down, or so hot organic material instantly combusts.

But for life's most primitive forms (such as plankton), the chances of survival and even thriving rise remarkably. Scientists have long postulated that very basic micro-organisms, such as bacteria and viruses, could indeed survive space travel by going into a dormant state called a spore. Essentially in suspended animation, spores could remain viable for millions of years, hitching rides on meteors or comets, or even drifting solo. Astrobiologists propose that the universe is in fact filled end to end with such microbes in a theory called panspermia.

Once a more hospitable environment is encountered, the microbe becomes active once more. Polluting pristine environments with Earth-borne microbes has even been a factor NASA scientists take into consideration for missions to sites where life might exist, such as Jupiter's moon Europa.

TagsISS, International Space Station, Plankton, Spore