Juno is a mission to explore and understand the immense Jupiter system, comprised of the Sol system's largest planet and 63 moons. Jupiter is an interesting target for exploration because of the extremes it encompasses, both in size and atmospheric conditions. According to the NASA mission overview, Juno is such an interesting cause because:
"Juno will let us take a giant step forward in our understanding of how giant planets form and the role these titans played in putting together the rest of the solar system."Juno will answer questions about Jupiter's formation and composition, by investigating the possibility of a solid core, and by observing the theorized metallic hydrogen layers deep inside Jupiter. It will also map Jupiter's immense magnetic fields, and observe its magnificent auroras.
Juno is scheduled for launch in August 2011, with Jupiter orbital insertion in July 2016. The mission is scheduled for deorbit in 2017, but with the past successes of NASA's great robotic probes such as the Cassini/Huygens probe, an extended mission time wouldn't surprise me.
Juno is part of NASA's New Frontiers Program, which also includes the New Horizons probe, destined to reach Pluto in 2015.
It should be a very interesting mission, and I can't wait to see the pictures!
NASA's Juno Mission Overview
Image credit: NASA/JPL