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Friday, October 17, 2008

Amazing Water Bears

Water Bears Amaze Scientists - Yahoo! News

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'Alien' Water Bears Amaze Scientists By Lee Pullen Astrobiology Magazine posted: 16 October 2008 06:56 am ET

Astrobiologists work at the cutting edge of scientific research, investigating the possibility of life elsewhere in our universe. They are, however, plagued by a single, potentially critical problem: a lack of samples. Studying alien organisms is naturally difficult when none have been discovered.

Some scientists have taken a novel approach to circumventing this issue. Life on Earth is abundant, and often very hardy. Extremophile creatures exist in places we would consider as exceptionally hostile, such as deep in the ocean floor or areas where even a drop of water is almost impossible to find. Similarly, some of the potential places for life elsewhere in our solar system, such as the planet Mars, Jupiter's moon Europa, or Saturn's moon Titan, have conditions that are viewed as extremely hostile but still potentially survivable. So extremophile organisms are studied in lieu of genuine extraterrestrial samples, to see if they could survive the rigors of life beyond the Earth.

Nearly indestructible

Dr. Daiki Horikawa from NASA Ames Research Center has been examining strange creatures called tardigrades for the last seven years. He explains, "tardigrades are small invertebrate animals, 0.004 to 0.04 inches (0.1 to 1.0 mm) in body length, that live in terrestrial mosses, soil, or lichens. They also inhabit ocean and polar regions." Often known by their nickname, "water bears," studies of these bizarre creatures have surprised scientists.

Recent research has shown that water bears can survive the dangerous conditions of space. Previously, the only organisms that have been exposed to the radiation and vacuum of space and lived to tell the tale are certain types of bacteria and lichen. That simple animals like tardigrades also can survive gives more credence to the theory of panspermia, which claims that organisms could move from world to world after travelling though space.

Perhaps the most interesting feature of tardigrades is their ability to enter a suspended animation-like state when they cannot find enough water. In this kind of survival mode they become very resistant to harsh environments. When they encounter water they awaken and become active again.

Horikawa realised that if he wanted to produce worthwhile, reproducible studies, he would have to raise samples of water bears in laboratory conditions. Those collected from their natural habitat can be quite different to one another because of climate variations, nutritional differences and other environmental considerations. So Horikawa raised a collection on agar plates with green algae for food. Although labor-intensive, this produced uniform water bears which were then separated into groups and exposed to various stresses to see how tough they really are.

A barrage of tests

First they were heated up to sizzling temperatures of 194 F (90 C). Then a group was frozen at -321 F (-196 C). The next batch was given a dose of radiation similar to what they would receive in space — around 4,000 times stronger than that which would make humans ill. The last selection was covered in a dissolving chemical (99.8% acetonitrile, a chemical which may be present in Titan's atmosphere).

The results, published in a recent issue of the journal Astrobiology, were that water bears in their suspended animation state survived everything that was thrown at them. Active creatures were less fortunate, but some did tolerate the extreme conditions. Now their tolerances to specific stresses are known, plans are underway to expose them to many harsh environments simultaneously.

If extraterrestrial life is as tough and resilient as water bears, then other worlds could be inhabited. "It's a possibility that water bear-like creatures could survive and thrive on other planets despite harsh environments," says Horiwaka. "Judging from data of the planets in our solar system, there could even be some in their suspended state on Mars." There is a chance that Earth-based water bears could be transported to other worlds via meteorite impacts, but more research is required before this is known for sure.

Self-repairing DNA

Horikawa plans on continuing his research, particularly looking at the ability of water bears to repair DNA after being exposed to high levels of radiation. As he says, "the most fascinating feature of tardigrades for me is their ability to survive complete dehydration of the body and high tolerance to radiation exposure which must cause critical DNA damages."

Horikawa's method of rearing water bears in the laboratory could lead to many more studies of these amazing animals, and may help astrobiologists in their search for genuine extraterrestrial life.

Knowing the survival tricks of water bears also could one day be a key component in enabling the human exploration of the universe.

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Some water bears eat microscopic animals, while others consume algae. Credit: Daiki Horikawa, NASA Ames
Water bears are fundamentally aquatic animals, using their eight legs to walk in liquid. Credit: Daiki Horikawa, NASA Ames
Alien creatures with survival features like those used by water bears could exist on other worlds. Credit: Daiki Horikawa, NASA Ames
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NASA scientists pick spots to search for signs of extraterrestrial life. Credit: NASA/JPL-CalTech
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Astronaut Gloves Tested for Biological Contamination By SPACE.com Staff posted: 25 March 2009 09:34 am ET

Astronauts recently had their gloves swabbed in an early effort to develop planetary protection measures that prevent humans from accidentally contaminating the moon or Mars on future missions.

The crew of space shuttle Discovery and the International Space Station used a new laboratory device to examine biological material on the gloves of astronauts servicing the space station. Such tests could help NASA understand and plan around how to prevent the spread of Earth life to other planets.

"This simple approach, designed to monitor the spread of biological material in space, takes very little crew time to perform and could prove to be a useful step in planning future human missions to the moon and Mars," said Jake Maule, a geophysicist with BAE Systems.

The space station's Lab-on-a-Chip Portable Test System, or LOCAD-PTS, can rapidly detect and identify a variety of biological materials relating to bacteria and fungi, and has been on the space station since March 2007.

A recent spacewalk on March 19 provided the opportunity for astronaut Sandy Magnus to swab the spacesuit gloves of STS-119 mission specialists Steve Swanson and Richard Arnold, both before they exited the space station airlock and after they returned.

The spacewalkers installed a solar array truss segment (S6), which had been sampled and analyzed with LOCAD-PTS prior to launch with Discovery on March 15. NASA clean room procedures ensured that most surfaces of the hardware remained clean, but the lab device did detect small levels of fungi — especially in the fabric gap spanners, or safety elements that connect handrails and allow astronauts to move safely around the outside of the space station as they work.

Dead or live bacteria or fungi that remained on the S6 segment would have likely ended up on the spacewalker gloves. An analysis by LOCARD-PTS will likely turn up results after the space shuttle undocks for the journey home.

"These guys were the first guys to put their hands on it since it's been in space, so we were swabbing their gloves and so we'll know what's just out there in space versus when we go looking for life on other places," said Tony Antonelli, shuttle pilot for Discovery.

Any life that survives in space may also evolve in unexpected ways. Studies from two recent space shuttle missions showed that Salmonella bacteria, which cause food poisoning on Earth, became more virulent in the space station's microgravity environment. Tiny creatures called water bears have also demonstrated the ability to survive exposure in the harsh vacuum of space.

LOCAD-PTS should help develop procedures and tools to keep an eye on biological contaminants that might creep aboard expeditions to the moon or Mars, said Mike Effinger, a LOCAD project manager at NASA's Marshall Space Flight Center in Huntsville, Ala.

"Because spaceflight currently is limited to low Earth orbit, requirements don't exist yet in regard to biological contamination of other planetary surfaces by human missions," Effinger said. "This study seeks to begin development of test procedures that can be further developed on the moon in preparation for the human exploration of Mars."

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