(Describer) Streams of light collide to create a globe filled with water. Title: Science Nation. Microscopic organisms are like thin spirals.

(male) Oh, this is so beautiful!

(male narrator) Check out these living corkscrews, exotic in more ways than one. This newly discovered bacteria is what's called an extremophile--a microbe that thrives where life would seem to be impossible. In this case, the salty alkaline mud at the bottom of dried-up Owens Lake in California. I have been to many of the most hostile and extreme environments on earth.

(narrator) NASA scientist Richard Hoover knows all about extremophiles. He and his colleagues cultivate a virtual zoo of them at the Marshall Space Flight Center in Huntsville, Alabama. This is a high-temperature brine.

(Describer) He holds up a bottle.

Actually, we do have microorganisms growing in there. You see--you see when we're swirling?

(Describer) He shakes the cloudy liquid.

(narrator) Extremophiles were unknown to scientists until just a few years ago.

(Describer) Steam rises from geysers.

But then researches started finding growing things in unlikely places: inside the geysers at Yellowstone National Park and within deep-sea hydrothermal vents called black smokers.

(Describer) A plane flies over tundra.

On the other hand, Hoover spends a lot of time studying extremophiles from cold regions.

(Describer) Someone kneels on a patch of snow.

He's gone to the ends of the earth to find them, such as this expedition to Antarctica's remote Lake Untersee in 2007, coordinated through the National Science Foundation.

(male) Wonderful find, wonderful find.

(Describer) Samples are taken from the snow and from under ice through a hole.

(narrator) Once Hoover finds the extremophiles, the race is on, back in Alabama, to grow them. First thing: find out what they eat. There are a whole array of bacteria that live entirely on chemicals. They don't utilize light or ordinary food.

(Describer) They're shown under a microscope again.

(narrator) So, what is NASA's interest in these extremophiles? Hoover says they may provide clues as to what life elsewhere in the solar system or beyond might look like. It's a field of study called astrobiology that considers that life on other worlds might be much like microbes living in similar harsh conditions here on earth.

(male) I think it is quite possible that when we go to collect samples from the icy moons of Jupiter or the polar ice caps of Mars, we may very well find microorganisms.

(narrator) He says it is possible, over billions of years, life has spread around the solar system, a sort of cosmic cross-pollination. Microbes can live in the ice deep within comets, frozen there for eons, until a collision with another planet or moon delivered it to a new home. Possibly, when we get a chance to bring back ice from the polar caps of Mars, we might find biology that looks like Earth life and it might have originated on Earth and was carried to Mars.

(Describer) He taps a nail to chip a rock.

[tapping]

(narrator) To test that theory, Hoover cracks open so-called carbonaceous meteorites, which are the remains of cometary debris or water-bearing asteroids that have hit the earth. This is part of the Murchison meteorite, which fell to earth in Australia in 1969.

(Describer) Hoover and another man examine a microscopic image.

Yeah, feathery crystals, it looks like.

(narrator) Being careful to avoid contamination, he examines their insides with an electron microscope.

(male) They're older than the planet earth, which is accepted as 4.5 billion years old. I like to say that these carbonaceous meteorites are actually older than dirt.

(Describer) He smiles.

[chuckles]

(narrator) Some structures imaged from these meteorites are intriguing, bearing striking similarities to bacteria here on earth. Could these be the fossilized remains of extraterrestrial life?

(male) I am convinced what I am finding in the carbonaceous meteorites are, in many cases, biological in nature.

(narrator) It is a highly-controversial interpretation. We have, for a long time, thought that all life, as we know it, originated on earth, and there isn't any life anywhere else. That's an idea, it's a hypothesis. It's a totally unproven hypothesis.

(Describer) An auger is drilled into ice.

(narrator) Hoover hopes his work will help get at the truth. And as interplanetary probes become more sophisticated, scientists may eventually turn up a biological sample. Then we'll know if life out there looks anything like it does here. For Science Nation, I'm Bruce Burkhardt.