Mercury has always fascinated me because we knew so little about the planet closest to the Sun. NASA's MESSENGER spacecraft has changed this as "
"During the extended mission we will spend more time close to the planet than during the primary mission, we'll have a broader range of scientific objectives, and we'll be able to make many more targeted observations with our imaging system and other instruments". "MESSENGER will also be able to view the innermost planet as solar activity continues to increase toward the next maximum in the solar cycle. Mercury's responses to the changes in its environment over that period promise to yield new surprises."
Sky Guy in VA