magazine previews the latest flyby in Seeing a new side of Mercury
At 12:31 A.M.
EDT October 6, NASA's MESSENGER spacecraft will skim within 125 miles (200 kilometers) of Mercury's surface. MESSENGER — short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging — has flown past Mercury once already this year. On January 14, the craft came equally close to the innermost planet, imaging Mercury's cratered surface and studying its puzzling magnetic field and thin atmosphere.
Yet on October 6, the Sun will be illuminating the hemisphere that lay in darkness back in January. "MESSENGER will view parts of Mercury no one has ever seen up-close before," says Astronomy
magazine Senior Editor Richard Talcott. Not only will the probe observe the opposite half from what it did last time, but it also will reveal some 30 percent of the planet's surface missed by the Mariner 10 spacecraft in the mid-1970s. This represents the largest area of terra incognita remaining in the solar system.
"MESSENGER's January flyby revealed unexpected features in the new areas it observed," Talcott adds. "Now, expectations are running high that more bizarre terrain may show up."
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