2008-09-09 09:20:00
A tiny, six-legged critter that can suspend all biological activity in extreme
environments survived a journey to space that would have instantly killed any
human and most other life forms.
In the first test of its kind, researchers exposed the hardy segmented
creatures, called "water bears," to the open and harsh vacuum of space, with
all its deadly radiation, on a spacecraft in low-Earth orbit. Many of them
survived.
The water bears, known formally as tardigrades, have an ability similar to
brine shrimp (also known as Sea Monkeys), which are familiar to many children
for their ability to come to life after being sent to homes by mail-order.
Tardigrades are speck-sized things, less than 1.5 millimeters long. They live
on wet lichens and mosses, but when their environment dries out, they just wait
for a return of water. They also resist heat, cold and radiation.
The radiation resistance was most surprising to scientists.
The tardigrades were aboard the FOTON-M3 spacecraft launched by the European
Space Agency (ESA) in September 2007 and were exposed to open space conditions,
the scientists reported today. They were examined upon return to Earth.
Most survived exposure to the vacuum and cosmic rays, and some even survived
the exposure to the deadly levels of solar UV radiation, which are more than
1,000 times higher than on the surface of the Earth.
The survivors "could reproduce fine after their space trip," according to a
statement released today by Cell Press, the journal that published results of
the test.
How the post-flight tardigrades could do it "remains a mystery," the
researchers write.
UV rays consist of high-energy light particles that cause severe damage to
living tissue, as is evident when you get a sunburn. But more so, they can also
damage cells' genetic material, causing skin cancer, for example. The
radiation, in wide-open space, also is thought to be sterilizing.
The work was led by K. Ingemar Jonsson of Kristianstad University in Sweden.