Engineers are readying a NASA spacecraft for a May 11 launch to one of the least-explored planets in the solar system. If all goes according to plan, the craft will begin orbiting Mercury, the sun's closest planet, in 2009 and take the first close-up images of the pockmarked body since 1975.
The craft, known as MESSENGER (for Mercury Surface, Space Environment, Geochemistry, and Ranging), will be the first to image the entire planet, a place of extremes (SN: 7/8/00, p. 24: Available to subscribers at Forgotten Planet). At any given moment, one side of Mercury is hot enough to melt zinc while the other is cold enough to freeze methane—a temperature range of 600°C.
During its mission, MESSENGER will search for signs of ice in permanen