Dr. Bortrum
10/16/2008
Tiny Bears in Space
In the "newscripts" section of the September 22 issue of Chemical & Engineering News (C&EN), Ivan Amato describes what happened to a very lucky guy undergoing a test in a pressure chamber at NASA’s facility in Houston, now the jonhson Space Center. This was back in 1965 and the fellow was in a pressure chamber under conditions approximating the vacuum in space. Unfortunately, his space suit leaked and he lost consciousness in only about 14 seconds! Fortunately, the engineer’s monitoring the experiment reacted quickly and repressurized the chamber in time to save him. The last thing he remembered before passing out was the water on his tongue starting to boil!
The thought has often occurred to me that those astronauts out there in space doing their space walks are really in trouble should they get a rip in their space suit. We humans obviously aren’t made to live in space unprotected. Aside from the perils of the vacuum and lack of oxygen in space, there is also the intense UV radiation from our sun and various energetic particles in the cosmic radiation from the stars and other heavenly bodies such as black holes eating up stars. It’s not an inviting environment for life.
Which brings us to water bears, the main subjects of the C&EN article. Amato cites the work of Ingemar Jonsson of Kristianstad University in Sweden and and his collaborators in Sweden and Germany on water bears. I must admit I was surprised that, on searching the Internet, it seems that everyone knew about water bears but me. For example, one of the first sites to pop up was a blog of Colbert of TV’s Colbert Report (pronounced without the t’s). A more authoritative source that I found was Jonsson’s own blog, tardigradesinspace.blogspot.com.
OK, if, like me, your first thought was that the water bear is similar to a polar or grizzly bear, you should know that the water bear is a tardigrade. Again, if, like me, this does nothing to clear things up, my dictionary defines a tardigrade as "any of a phylum (Tardigrada) of minute water animals with segmented bodies and four pairs of unsegmented legs, often regarded as primitive arthropods." Water bears are indeed "minute", only measuring from about a tenth to 1.5 millimeters in size, up to about the size of an "o" if your printer prints out the same size type as mine. They do have bearlike claws on their feet for grabbing onto bits of foodstuffs. You can see a water bear in motion on YouTube. Amato quotes biologist Robert Goldstein as saying the water bear is "adorable"; you may or may not agree.
There are many species of water bears, most of them living in mossy or lichen-rich areas. These habitats are normally wet or moist but may dry out significantly, becoming more like deserts. Under such situations, the water bears go into a desiccated or dried out state in which they shut down their metabolism, curl up into a barrel shape and may go for years without water. Apparently, you could stick one of these dried out water bears in a chamber where the temperature is only a degree or so above Absolute Zero and it would survive! It’s one tough little critter.
Considering that the water bear is such a tough animal, Jonsson and his colleagues teamed up with the European Space Agency in project TARDIS, "Tardigrades In Space". TARDIS involved taking some of these dried out water bears and sending them out into space, where they would be exposed to conditions in space and see if they survived. This was done back in September last year when some 3,000 of the tiny water bears were packed in groups and sent into orbit aboard the Foton-M3 space capsule. Once in orbit the different groups of dried out water bears were exposed to various conditions in space. Some were just exposed to the vacuum of space but were shielded from the UV radiation. Others were exposed to the space vacuum and to UV-A and/or UV-B and/or other UV radiation. Two types of water bears were sent into space - Richtersius coronifer from Sweden and Milnesium tardigradum from Germany. I’ll just refer to them as German and Swedish water bears.
After 10 days exposure to conditions in space, the Foton-M3 capsule was recovered and the little dried out "tardinauts" sent to Sweden to be rehydrated. Needless to say, many of the water bears survived the trip or I wouldn’t be writing about them. For the most part, exposure to the vacuum in space was a piece of cake for the water bears. Most survived and many went on to lay eggs and reproduce with normal water bear offspring. Exposure to the UV radiation was a different matter. Most of those exposed to the full effect of the UV radiation died, with few surviving. However, most of the survivors seem to have come to on hydration, only to give a few kicks of those little legs and then die.
According to Jonsson’s blog, the "German" water bears were a hardier bunch, about 12 percent surviving the UV-A/UV-B radiation and going on to produce eggs and offspring. However, their output was lower than that of water bears kept as controls here on Earth. Only a handful or less of the water survived the most severe exposures to the full range of UV radiation, which is a thousand times more intense than here on Earth.
To sum up, these little water bears are the first animals that have survived unprotected exposure to conditions in space. Previously, bacteria and lichen have successfully survived such exposure to outer space. On his blog, Jonsson expresses surprise that there has been so much media interest in the results of their TARDIS experiment. He hopes that tardigrades will be appreciated more as models organisms for experimental studies and notes that the National Human Genome Research Institute here in the U.S. has decided that the whole genome of a targdigrade should be sequenced.
Who knows? Perhaps water bears will become like ant farms, available in pet stores. I presume they would be sold in containers covered with a powerful magnifying glass! They should be relatively easy to maintain. When you go on vacation, just dry them out and add water when you return!
Allen F. Bortrum
