The New Horizons Jupiter encounter is under way! The spacecraft began collecting data on the Jovian system this week, starting with black-and-white images of the giant planet and an infrared look at the icy moon Callisto on Jan. 8.

These were the first of about 700 observations of Jupiter and its four largest moons planned from now until June. They include detailed scans of Jupiter's turbulent, stormy atmosphere and dynamic magnetic field, a peek into its faint ring system, maps of the composition and topography of the moons Io, Europa, Ganymede and Callisto, and a look at Io's volcanic activity. Also in the flight plan: the first-ever trip down the long "tail" of Jupiter's magnetic field, which extends tens of millions of miles beyond the planet.

The New Horizons mission operations team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Md., works closely with science operations team, based at Southwest Research Institute (SwRI) in Boulder, Colo., and mission scientists to plan, test and eventually send the observation commands to the spacecraft, which runs the sequences from memory in its onboard computers. Data are stored on the spacecraft's recorders and sent back to Earth through NASA's Deep Space Network antennas. The newest images will be available on the New Horizons Web site next week.

"Our ground team has worked very hard to get to this point," says New Horizons Principal Investigator Alan Stern, of SwRI. "Now the curtain is rising on the next stage of Jupiter-system exploration. It's exciting!"

Closest approach to Jupiter comes Feb. 28, when the spacecraft zooms within 2.3 million kilometers (1.4 million miles). New Horizons uses Jupiter's gravity to speed toward its ultimate destination, Pluto.