Airdate: Mar 10, 1999
Scientist: Chris McKay
Here on Earth, water is the elixir of life.
"It flows between us, over us and with us. And it is time, strength, tone, light life and love." So wrote the poet Robert Frost about water- that essential substance which is a hallmark of life on Earth. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.
"When we look at life on Earth we see that every single organism on this planet requires liquid water to reproduce and grow. There's no organism that can do without it.
Chris McKay is a scientist in the Space Science Division at NASA's Ames Research Center.
"Liquid water provides the medium in which life processes occur. In which reactions in ourselves, the proteins fold and unfold, the DNA comes apart and reproduces, all occurs within the medium of liquid water and water plays a key role in providing not just the medium but a context for guiding those molecules in what they do. It must be some fundamental biochemical requirement and it could be that no life form's been able to figure out another way to do it."
So when we look at places on Earth where liquid water is abundant-- the tropical rainforests, for example-- we'll see a richness of life quite unlike anything you'll find in Earth's deserts and polar ice caps.
"There are places on Earth where there's no life. And particularly those are places where water isn't liquid. For example, Greenland. The vast ice sheet on Greenland isn't green because no organism on Earth can live with water as ice. The water has to be liquid before organisms can live there. It seems like the limits of life's ability on Earth are defined by the availability of liquid water. Ice doesn't do it."
In its continuing search for life on other planets, NASA is paying close attention to places where they've found evidence of liquid water.
Pulse of the Planet is presented by the American Museum of Natural History. Additional funding for this series has been provided by the National Science Foundation.