New views of Mercury arriving today

October 07, 2008|By Frank D. Roylance | Frank D. Roylance,frank.roylance@baltsun.com

Planetary scientists in Maryland should have a trove of never-before-seen views of the planet Mercury on their computer screens today.

NASA's Messenger spacecraft flew within 124 miles of the sun's nearest neighbor early yesterday, and scientists at the Johns Hopkins University's Applied Physics Laboratory near Laurel were expecting the first high-resolution photographs to arrive from the spacecraft today, beginning shortly before 2 a.m.

Already yesterday, long-range, low-resolution images snapped for navigation purposes and transmitted hours before the flyby had scientists enthralled, according to principal investigator Sean Solomon, of the Carnegie Institute of Washington.

"Everything in the view of those early images ... is territory not seen by any spacecraft before," he said. Geologists poring over the navigation photos said the newly viewed portion of the planet appears to have the same kinds of large impact craters and long fault lines seen during Messenger's first flyby last January. The long faults are believed to be cracks in the crust, formed as Mercury cooled after its formation 4.5 billion years ago.

Scientists are eager to compare terrain imaged in January with the 30 percent of the planet's surface photographed for the first time yesterday.

Mission managers at APL said the spacecraft appeared to be on course and in good health. At 4:21 a.m. yesterday, it flew within a few hundred yards of the mission's aim point, just 124 miles above the planet's surface.

The images and other data recorded yesterday were stored until the spacecraft could turn its high-gain antenna toward Earth this morning and begin transmitting them to Earth.

The highest priority pictures were expected to arrive today between 1:49 a.m. and 8:32 a.m.

The Messenger spacecraft, launched in 2004, was designed and built at APL. Its Mercury flyby in January was the first by any spacecraft since Mariner 10 flew past in 1975.

Messenger is scheduled to make another close pass next September as controllers use the planet's gravity to further cut its speed. In March 2011, they hope to maneuver the spacecraft into orbit around Mercury to begin at least a year of close-up scientific observations.

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