Juno to Show Jupiter's Magnetic Field in High-Def

When it comes to magnetic fields, Jupiter is the ultimate muscle car. It's endowed with the biggest, brawniest field of any planet in the solar system, powered by a monster engine under the hood.

Figuring out how this mighty engine, or dynamo, works is one goal of NASA's Juno mission, which is scheduled to begin its five-year, 400-million-mile voyage to Jupiter in August 2011. Juno will orbit the planet for about a year, investigating its origin and evolution with eight instruments to probe its internal structure and gravity field, measure water and ammonia in its atmosphere, map its powerful magnetic field and observe its intense auroras.

The magnetic field studies will be the job of Juno's twin magnetometers, designed and built at NASA's Goddard Space Flight Center in Greenbelt, Md. They will measure the field's magnitude and direction with greater accuracy than any previous instrument, revealing it for the first time in high-def.

"Valuable information about Jupiter’s magnetic field was gathered by the Pioneer 10 and 11 missions in the early 1970s and Voyagers 1 and 2 in the late '70s," says NASA Goddard's Jack Connerney, Juno's deputy principal investigator and head of the magnetometer team. Connerney is collaborating with the mission's principal investigator, Scott Bolton, at the Southwest Research Institute in San Antonio, Texas. "But previous spacecraft orbited among Jupiter's moons; Juno, a polar orbiter, will be the first magnetic mapping mission to Jupiter."

"Mapping Jupiter's magnetic field is one of the very few ways available to learn about Jupiter's deep internal structure," says Juno's project scientist, Steven Levin of NASA's Jet Propulsion Laboratory in Pasadena, Calif., which manages the Juno mission. That's because Jupiter's atmosphere is compressed so much by its powerful gravity field that it becomes impenetrable to most sensing techniques.