The fastest spacecraft ever launched, New Horizons will make its closest pass to Jupiter on Feb. 28, threading its path through an "aim point" 1.4 million miles (2.3 million kilometers) from the center of Jupiter. Jupiter's gravity will accelerate New Horizons away from the Sun by an additional 9,000 miles per hour - half the speed of a space shuttle in orbit - pushing it past 52,000 mph and hurling it toward a pass through the Pluto system in July 2015.
At the same time, the New Horizons mission team is taking the spacecraft on the ultimate test drive - using the flyby to put the probe's systems and seven science instruments through the paces of a planetary encounter. More than 700 observations of Jupiter and its four largest moons are planned from January through June, including scans of Jupiter's turbulent, stormy atmosphere and dynamic magnetic cocoon (called a magnetosphere); the most detailed survey yet of its gossamer ring system; maps of the composition and topography of the large moons Io, Europa, Ganymede and Callisto; and an unprecedented look at volcanic activity on Io.
The flight plan also calls for the first-ever trip down the long "tail" of Jupiter's magnetosphere, a wide stream of charged particles that extends tens of millions of miles beyond the planet, and the first close-up look at the "Little Red Spot," a nascent storm south of Jupiter's famous Great Red Spot.
"Our highest priority is to get the spacecraft safely through the gravity assist and on its way to Pluto," says New Horizons Principal Investigator Dr. Alan Stern, of the Southwest Research Institute, Boulder, Colo. "But we also have an incredible opportunity to conduct a real-world-encounter stress test to wring out our procedures and techniques for Pluto, and to collect some valuable science data."
The Jupiter test matches or exceeds the mission's Pluto study in duration, data volume sent back to Earth, and operational intensity. Much of the data from the Jupiter flyby won't be sent back to Earth until after closest approach, because the spacecraft's main priority is to observe the planet and store data on its recorders before transmitting information home.
After such a long and thorough observation of the Jovian system by Galileo, it is really a great bonus to be able to scope out Jupiter with a suite of even more advanced instruments such a relatively short time later. It'll be particularly nice to get closer observations of the "Little Red Spot" as it grows, moves closer to, and interacts more with the famous Great Red Spot. Any observations of the Jovian satellites--in particular, Io and Europa--will be quite welcome as well.
When I was a kid, I would pore over the issues of National Geographic that featured extensive coverage of Viking at Mars and the Voyagers at Jupiter and Saturn. I'd goggle over the photos, and reread the articles until the pages were literally in tatters. That thrill's never really left me, and I'm sure I'm only one of millions eagerly awaiting our first closeup view of Pluto and Charon. I have to admit, though, that Jupiter's a pretty groovy opening act.
For more information on New Horizons, visit http://pluto.jhuapl.edu.