Wednesday, September 30, 2009

Messenger spacecraft OK after brief shutdown

NASA's Messenger spacecraft is healthy after a brief shutdown during Tuesday's flyby of Mercury.

Four minutes before the closest approach at 5:55 p.m., while the spacecraft was flying on battery power in Mercury's shadow, signals were lost and on-board systems went into "safe" mode.

Mission managers said that apparently was a reaction to an "unexpected configuration of the power system" while in shadow, or eclipse. Systems returned to normal operations at 12:30 a.m. today.

"Although the events did not transpire as planned, the primary purpose of the flyby, the gravity assist, appears to be completely successful," said Eric Finnegan, mission systems engineer at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

The shutdown meant that Messenger could not conduct all the imaging and science observations planned during the flyby.

But the maneuver still did return images adding about 5 percent of the previously unseen area of the planet's surface. That brings to 95 percent the total area of the planet that Messenger has imaged.

And the flyby's primary goal, as Finnegan mentioned - to adjust Messenger's trajectory ahead of a planned entry into orbit in 2011 - was successful.

Click here to see more pictures and information from the flyby.

The flyby was the third and final one before Messenger plans to enter Mercury's orbit in 2011. The spacecraft launched from Cape Canaveral in 2004.

IMAGE NOTE: On Tuesday, Messenger imaged Mercury's partially sunlit surface on its approach to the planet yesterday. This Wide Angle Camera image reveals approximately an additional 5 percent of the surface (outlined in red) that had been previously unseen by spacecraft. Among the many newly imaged surface features are impact craters, smooth plains, and an intriguing double-ring basin approximately 260 kilometers (125 miles) in diameter. Rembrandt basin straddles Mercury's terminator (along the right side of the image). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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