The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of researching several of the Solar System bodies, including the dwarf planet Pluto. New Frontiers was built on the innovative approach used by the Discovery and Explorer Programs of principal investigator-led missions. It is designed for medium-class missions that cannot be accomplished within the cost and time constraints of Discovery, but are not as large as Flagship-class missions. Juno is the next step in realising this program.
Juno is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA's Jet Propulsion Laboratory. Juno was selected in 2005 as the next New Frontiers mission after New Horizons. The desire for Jupiter was strong in the years prior to this, but there had not been any approved missions. The spacecraft was launched from Cape Canaveral Air Force Station on August 5, 2011, as part of the New Frontiers program, and entered a polar orbit of Jupiter on July 5, 2016, to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter's atmosphere.
Juno's mission is to measure Jupiter's composition, gravity field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds of 618 kilometers per hour (384 mph). The spacecraft will study the lights around Jupiter's north and south poles (auroras), too. Juno is powered only by solar arrays, commonly used by satellites orbiting Earth and working in the inner Solar System, whereas radioisotope thermoelectric generators are commonly used for missions to the outer Solar System and beyond. For Juno, however, the three largest solar array wings ever deployed on a planetary probe play an integral role in stabilizing the spacecraft as well as generating power.