The Sun is Setting on Phoenix

Based on a NASA news release

As fall approaches Mars' northern plains, NASA's Phoenix Lander continues to dig into the red planet's soil and deliver samples to its onboard science instruments for analysis.

Over the past two weeks, Phoenix's nearly 2.4-meter-long (8 foot) arm moved a rock named "Headless" about 0.4 meters (16 inches) and snapped an image of the rock with its camera. Then the robotic arm scraped the soil underneath the rock and delivered a few teaspoonfuls of soil onto the lander's optical and atomic-force microscopes. These microscopes are part of Phoenix's Microscopy, Electrochemistry and Conductivity Analyzer.

Scientists are conducting preliminary analysis of this soil sample, nicknamed "Captain Hessian." The soil piqued their interest because it may contain a high concentration of salts, said Phoenix mission scientist Diana Blaney of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

As water evaporates in arctic and arid environments on Earth, it leaves behind salt, which can be found under or around rocks, Blaney said. "That's why we wanted to look under Headless, to see if there's a higher concentration of salts there." These salts could indicate that liquid water was once present on Mars, possibly providing a habitat for life.

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