Sunday, September 14, 2008

Water Bears in Space!


© USDA
No, not a new Muppet Show skit. Water bears (tardigrades) are intriguing aquatic microscopic (0.5 mm or 0.02 inches) multicellular animals. They have a head and six limbs with claw-like structures. Their liquid habitat range is quite large - they've been found within ice, in oceans down to almost 4 miles beneath the surface, in mountain ponds, and in droplets of water in moss and lichens. They can survive long (7 years) periods of total dehydration, acid attacks, and extreme temperatures and pressures. Recently Dr. Ingemar Joensson of Kristianstad University of Sweden, sent up 3,000 water bears into space for 12 days and discovered that water bears are able to survive the vacuum and cosmic radiation of space.

OK, most did not survive the intense ultraviolet radiation they encountered above the Earth's atmosphere. But some did. These little "bears" are tough! It's no wonder that some people think water bears are extraterrestrials.

But it does make one pause - could life spread out from a planet and evolve surviving in space? I've mentioned transpermia before - the idea that microbes or the organic precursors of life can spread from one planet to another, usually through meteoric impacts. Now it is feasible that multicellular life forms could traverse space.

Ah, but meteors are intensely hot when the streak through the atmosphere, are they not? Yes, but only on the surface. Many times the core is still cold. A dehydrated microscopic multicellular creature resting in the core could conceivably survive the trip. Could a meteor strike on the Earth send up a shower of water bear laden rocks into space, to eventually land on Mars? An interesting thought. Wouldn't it be crazy if when we do discover life on Mars, it turns out to look a lot like a water bear?

So here's to the water bear, possible intrepid space explorer!

(And maybe we ought to be just a bit careful when bringing back rock samples from other planets, moons, and even asteroids...).

References:

Mach, Sabine and Martin. "Tardigrades (Tardigrada): images, video clips, text and monthly magazine." Tardigrades. Sept. 2008. Web. 14 Sept. 2008. <http://www.tardigrades.com/>

"Transpermia." Transpermia - microbes hitch a ride between planets. The Planetary Society Australian Volunteers. 26 Aug. 2008. Web. 14 Sept. 2008. <http://users.tpg.com.au/users/tps-seti/swaprock.html>.

"Unique animal species can survive in space." SpaceRef. 10 Sept. 2008. Web. 14 Sept. 2008. <http://www.spaceref.com/news/viewpr.html?pid=26387>.

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