NASA's Phoenix Mars Lander found evidence of water-based ice on Mars, confirming some scientists' theories. Scientist Peter Smith of the University of Arizona discusses the discovery.
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As part of its mission to understand the history and properties of the Martian arctic, the Phoenix Lander took several pictures earlier this week of a trench near the spacecraft. Those photos, as highlighted here, showed eight small chunks of white material.
Four days later, the Lander took photos of the same spot again, but this time the material was gone. And as the researchers say, there's only one explanation: ice that evaporated.
To help us understand these findings, we turn to the lead scientist for the mission, Peter Smith of the University of Arizona.
And when did you get the first signs that you may have located ice so close to the Martian surface?
PETER SMITH, University of Arizona: The first chance we had to see the surface itself was looking underneath the Lander with our robotic arm and its camera.
And we saw that the thrusters had pushed away the local soil, the dry soil that we see around us, and exposed an underlying layer, which was both bright and hard. Some of us thought that was ice, but we couldn't prove it from just that picture.
How do you know it's frozen water, as opposed to another substance, like frozen carbon dioxide, what people call dry ice?
Frozen carbon dioxide is certainly a logical choice here, because in the winter it's probably 30 centimeters deep in frozen carbon dioxide. But as the temperatures warm up in the arctic summer, it gets way too warm for carbon dioxide ice. It would be like finding snow in the desert in the summer. So it's very unlikely, if not impossible.