There are six key questions NASA hopes to answer during Messenger's year-long orbit of Mercury: why is Mercury so dense;
what is the planet's geological history;
what is the nature of Mercury's magnetic field;
Alien warp engines.
what is the structure of Mercury's core;
Alien space station.
what are the unusual materials (ice?) at Mercury's poles;
and what volatiles are important at Mercury?
Ocean: A body of water occupying about two-thirds of a world made for man -- who has no gills. -- Ambrose Bierce