Mercury spacecraft offers new data

NASA's MESSENGER spacecraft has completed its one-year primary mission to study Mercury, revealing new insights into the planet, researchers say. The spacecraft captured nearly 100,000 images while orbiting Mercury and recorded data that reveal new information about the planet's core, its topography and the mysterious radar-bright material in the permanently shadowed areas near the poles, the researchers said. "Mercury is the last unexplored planet," said UC Santa Barbara physicist Stanton Peale, who devised the procedure used for detecting whether Mercury had a liquid core. The way Mercury was formed, he said, may provide hints about the formation of the solar system. Mercury's core is larger than expected, almost 85 percent of the planetary radius, whereas Earth's core is just over half of the planet's radius, researchers said. Other findings include a topographic model of the planet's northern hemisphere that shows a smaller variation in elevations compared to those of Mars or the moon, a UC Santa Barbara release reported. Radar-bright features at the poles located in areas of permanent shadow have been found to be consistent with a water-ice hypothesis, researchers said, but further tests will be required, using instruments aboard MESSENGER.