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03-寻找火星生命

NARRATOR: To inform the search for life on other planets, scientists observe how life adapts to the harshest regions on Earth.

In frozen tundra. . . in the driest desert. . . one can still find tough little organisms called "extremophiles."

Astrobiologist Chris McKay is an expert on extremophiles. He's discovered them in Earth's most unforgiving places.

Some closely resemble the extreme conditions on Mars. He is co-investigator on Phoenix.

McKAY: As we move into the hills, we find scenes like this. . . rocks. . . red rocks, really Marslike.

Here, we find one of my favorite examples of desert extremophiles. . . organisms living under stones in deserts.

They're cyanobacteria. They're green. They photosynthesize. They need light, but they also need water.

Living under a stone is a way that they get a little wetter, more shielded environment.

But they have to grow under stones that allow light to come through.

And about 1% of it reaches where these organisms are living, and that's enough light for them to grow.

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