Dispatch from Mars, Sol 4

Lander's touchdown may have exposed underlying ice

It was a good news/bad news day on Mars Thursday, with a tentative sighting of ice by the Mars Phoenix Lander, but also a newly discovered glitch in the oven system that will analyze soil samples.

ROCK OR ICE? Tabular features at top center of this image, taken by a camera on Mars Phoenix Lander, may be either ice or rock. The features run parallel to one of the lander’s legs. Scientists suspect the material was exposed when the craft’s descent thruster blew away topsoil. JPL/NASA, Univ. of Arizona

Scientists reported the findings during a May 30 briefing about the lander’s fourth day (or Sol, for Mars time) on Mars. Phoenix has been parked on the planet’s chilly northern plains since its successful landing May 25.

Flexing its muscles for the first time, the robotic arm on Phoenix took an image of exposed material beneath the lander that is either rock or ice. The material was probably brought to the surface when exhaust from the craft’s descent thruster blew away topsoil.

“We don’t know what it is,” says Phoenix scientist Ray Arvidson of WashingtonUniversity in St. Louis, but his team is hoping it’s ice. That would indicate that ice lies just below the surface throughout the landing region and could be easily scooped up by the arm. Analyzing polar Martian ice to determine if it had ever melted and offered a habitat for life is one of the main goals of the Phoenix mission.

Over the next few days, scientists will command the robot’s camera to get closer to the exposed material and take pictures through different color filters in an effort to identify its composition. But the area isn’t close enough to the arm for it to reach out and scoop up the stuff.

Scientists are now debating the first place to dig and when to begin a practice exercise, in which the arm would make initial contact with the soil, scoop a small sample and then dump it. Once the arm begins regular operation, it will deliver samples to miniature ovens and a spectrometer.

However, researchers have discovered that one of the two filaments that heats and ionizes samples delivered to the ovens has a short circuit. Scientists are now investigating the problem and determining if the other filament, which is operating normally, can be used exclusively if needed, Bill Boynton of the University of Arizona in Tucson told reporters during the press briefing, which was at the university. Boynton said he was optimistic that a “workaround solution” would be found.

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