Of all environments, space must be the most hostile: It is freezing cold,
close to absolute zero, there is a vacuum, so no oxygen, and the amount of
lethal radiation from stars is very high. This is why humans need to be
carefully protected when they enter this environment. New research by
Ingemar Jönsson and colleagues published in the September 9 issue of Current
Biology, a Cell Press journal, shows that some animals -the so-called
tardigrades or 'water-bears'- are able to do away with space suits and can
survive exposure to open-space vacuum, cold and radiation.

This is the first time that any animal has been tested for survival under
open-space conditions. The test subjects were chosen with great care:
Tardigrades -also known as water-bears- are tiny invertebrate animals from
0.1 to 1.5mm in size that can be easily found on wet lichens and mosses.
Because their homes often fall dry, tardigrades are very resistant to drying
out and can resurrect after years of dryness. Along with this amazing
survival trick comes extreme resistance to heat, cold and radiation -so
tardigrades seemed like an ideal animal to test in space.

The dried-up tardigrades were aboard the FOTON-M3 spacecraft launched by the
European Space Agency (ESA) in September 2007 and were exposed to open space
conditions -i.e. to vacuum, UV radiation from the sun and cosmic radiation-
in a low Earth orbit of around 270km altitude. After their safe return to
Earth, it turned out that while most of them survived exposure to vacuum and
cosmic rays alone, some had even survived the exposure to the deadly levels
of solar UV radiation, which are more than 1000 times higher than on the
surface of the Earth. Even more so, the survivors could reproduce fine after
their space trip.

The tardigrades extreme resistance to UV radiation is perhaps most
surprising. UV rays consist of high-energy light particles that cause severe
damage to tissue, as is evident when you get a sun-burn. But more so, they
can also damage the cell's genetic material, causing for instance skin
cancers. For this reason UV is deadly for most organisms -it is even used as
a sterilising agent.

As Jönsson and colleagues write: "How these animals were capable of reviving
their body after receiving a dose of UV radiation of more than 7000 kJm-2
under space vacuum conditions [.] remains a mystery." It is conceivable that
the same cellular adaptations that let them survive drying out might also
account for their overall hardiness.

Source: Cell Press
http://www.physorg.com/news140092992.html

Posted by
Robert Karl Stonjek