Sept. 9, 2008 -- When it comes to surviving open exposure in space, a tiny invertebrate now stands out: tardigrades, also known as "water-bears." These small, segmented animals not only survived a 12-day orbital expedition, some members of the community felled by solar radiation actually recovered upon their return to Earth. "How these animals were capable of reviving their body … remains a mystery," said lead researcher Ingemar Jönsson, with Sweden's Kristianstad University, who writes about the discovery in this week's issue of Current Biology. In what is apparently the first test of an animal's ability to survive open exposure to space, tardigrades were packed aboard the European-funded Foton-M3 spacecraft launched by Russian in September 2007. The tiny invertebrates, which range in size from about 0.1 to 1.5 mm, are more commonly found on mosses and lichens. Because their habitats often dry up, the creatures are extremely hardy and can survive prolonged periods of total dryness. That seems to be just the beginning of their skills. Packed in ventilated chambers that were exposed to the vacuum of space, adults from two species of tardigrades were subjected to extreme heat, frigid cold, cosmic rays and deadly levels of solar ultraviolet radiation. They had no air, water or food. Most of the 3,000 creatures not only survived, but they went on to reproduce once they came back to Earth. About 12 percent of the animals exposed to ultraviolet radiation revived after being put back in water, a puzzling find since researchers presume the sterilizing rays broke down the tardigrades' DNA. "This type of radiation cuts the DNA strand effectively in most organisms," Jönsson told Discovery News. Further tests are needed to determine if indeed the animals' genetic material was indeed damaged and what sort of mechanisms tardigrades have to make such unprecedented repairs. The ultraviolet levels of radiation in space were more than 1,000 times more intense than what reaches the surface of Earth. The experiment was among 43 microgravity science investigations sponsored by the European Space Agency, Germany, Belgium, France, Italy, Canada and Russia aboard the Foton spacecraft, which circled about 168 miles above Earth. While no additional flights are currently planned, the researchers would like to fly tardigrades aboard the International Space Station to see if they could survive even longer forays in space. Related Links: |
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