Comparing Planets

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One of the goals of the missions to other planets is to learn more about our own. Studying the oven-like atmosphere of Venus, for example, may help us understand the changes that are taking place in Earth's atmosphere. And studying the frigid surface of Mars could help, too.

In fact, the Phoenix lander is scheduled to study the frozen Martian plains after it touches down this weekend. Its mission is to look for frozen water and the building blocks of life. But lead scientist Peter Smith says that comparing its findings to events on Earth could teach us about both worlds.

SMITH: I think it helps to think of Mars as being similar to the Earth. In the northern Arctic region of the Earth is a permanant polar cap. And surrounding the cap is what we call the permafrost region on the Earth. And this stretches down into northern Alaska and Canada and Siberia. And there is a substantial fraction of the subsurface that is composed of water ice and it's very similar, we think, on Mars. And we find the polar region on Earth is extremely sensitive to climate change. Our permafrost is starting to melt and the ice cap is shrinking. And we're wondering if the Arctic region on Mars shows indications of climate change on Mars. We think it's probably equally sensitive to climate change, and there may be signatures left in the soil above the ice.

So digging into the Martian tundra may help reveal how the planet's climate has changed in recent millennia -- and provide some insight into changes right here at home.

Script by Damond Benningfield, Copyright 2008

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