Life on Mars?

In this video excerpt from NOVA, learn about the discovery of water ice on Mars. Satellites analyzing radar waves bouncing back from Mars's polar caps reveal that if it all melted, there is enough water ice to cover the entire planet in an ocean more than 80 feet deep. However, just like a piece of dry ice on Earth goes directly from solid ice to vapor without forming a liquid, water ice on Mars behaves the same way because the pressure is so low. In activity six from the Education Collection that accompanies this video, students identify the top candidates for life in the solar system.