The Truth About Water on Mars: 5 New Findings

• Mars
• Phoenix Mission
• NASA
• research
• ice

The mineral calcium carbonate shows up all over the Earth—it's the key ingredient in limestone and some chalk, and people take it as a calcium supplement. Researchers have confirmed that the Phoenix Lander's examination of Martian soil turned up lots of calcium carbonate. The mineral, which the researchers found by cooking the soil, is a promising sign that liquid water existed at some point, Smith says, because it almost always needs water to form.

Carbon dioxide in the atmosphere first reacts with the water in the soil, then the water leaches calcium out of the ground to form calcium carbonate. The only other way the mineral is naturally created is through low-temperature volcanoes, Smith says, but only one of the Earth's many volcanoes is known to do it, so that explanation is unlikely.

Calcium carbonate carries another bonus for life-seekers: It prevents the soil from becoming too acidic, keeping it at a pH close to that of seawater on Earth.

CLICK FOR MORE The Truth About Water On Mars
Lesson 1: Layers of Ice	Lesson 2: Calcium Carbonate	Lesson 3: Martian Clouds	Lesson 4: Perchlorate Controversy	Lesson 5: Life on Mars

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