Soil Holds Key to Past Life of Mars

For some UC Berkeley scientists, looking at soil from Mars is like looking at a key to the planet's climate history. By analyzing soil samples from Mars, scientists have determined that water on the planet came from the its atmosphere, rather than from deep within the ground, as was previously believed. The discovery, led by Ronald Amundson, a UC Berkeley professor of soil science in the department of environmental science and policy management, gives new insight into the planet's climate that may reveal more about whether life ever existed on Mars. Amundson said analysis of the salt distribution in the soil suggests water on the planet came from the atmosphere by rain or dew. Scientists who previously interpreted the soil content believed the water moved up from sources deep in the ground. The salt distribution of the planet's soil shows that the water on Mars came from the atmosphere first and traveled down through the soil, Amundson said. Since chloride salt, which is more soluble, is found in larger concentrations beneath sulfate, the less soluble salt, Amundson said scientists could tell water reached the surface of the planet first, dissolving most of the chloride while leaving behind most of the sulfate as the water moved into the ground. In other research, NASA sent a spacecraft to the planet in May that uncovered icy soil last week, stirring excitement in the science community. Data released from NASA showed that the planet could support life, as evidenced by soil analyses.