As the MESSENGER space probe approaches Mercury for its first flyby and close-up view of that planet, project principal investigator Sean C. Solomon, of the Carnegie Institution for Science, explains the significance of the mission. Topics include Mercury itself, the MESSENGER spacecraft design, the thermal challenges of a mission so close to the sun, the purpose and nature of the orbital flybys as MESSENGER matches orbits with Mercury, and the six big scientific questions that inform the mission.
