New Horizons used the strong gravity of the massive planet Jupiter (320 times the mass of Earth) to boost it on its way to Pluto — but the flyby of Jupiter was also an opportunity to test the New Horizons instruments and do science at the same time.

Observations of the Jupiter system began about 60 days before the closest approach (on February 28, 2007) and ran for about 120 days after. Naturally, since the primary objective of the mission is to study Pluto and Charon, calibration and testing activities took precedence over the science activities in the Jupiter period. Indeed, since getting to Pluto is the number-one concern, making sure that the gravity assist went as planned took precedence over any other activities at Jupiter.

With the primary mission in mind, Jupiter encounter observations fall into three major categories:

• Calibration and testing observations
• Optical navigation observations
• Science observations

Calibration, testing and optical navigation observations were scheduled and provided with resources at a higher priority than science observations. Science observations were further prioritized by the New Horizons science team members. As many science observations as possible were scheduled within the constraints of the resource budgets allocated to Jupiter activities.

Science Priorities

The team divided Jupiter period science observations into four major categories:

1) Studies of Jupiter's atmospheric structure and storm behavior.    2) Observations to gather additional information on the major known moons/satellites of Jupiter including atmosphere, eclipse, global composition and/or feature maps for each major satellite.   3) Investigation of ring composition and a search for additional Jupiter satellites within the ring structures. 4) Studies of Jovian magnetosphere via local measurements of charged particle fluxes and by remote sensing of auroral emissions.

The next NASA mission to Jupiter is the second New Frontiers mission, Juno, set to launch in 2011.