The Juno mission to Jupiter: Lessons from cruise and plans for orbital operations and science return

摘要

This paper describes the Juno mission, including its experience during 3+ years of cruise, and focuses on plans for its orbital mission and science return at Jupiter. Previous papers focused on the history of the mission, development, launch, and early cruise, or on spacecraft operations lessons learned. Juno is a NASA New Frontiers spacecraft currently enroute to Jupiter where it will enter a polar orbit in July 2016 with 9 instruments to study its atmospheric composition and structure, magnetic and gravity fields, and polar magnetosphere. Juno's prime science goal is to understand the origin and evolution of Jupiter, thereby shedding light on the formation of the Earth and other planets. Its science objectives are designed to be satisfied with 30 orbits, a spin-stabilized solar powered spacecraft with radiation shielding, and a unique payload including microwave receivers, Xand Ka-band gravity science hardware, magnetometers, low- and high-energy particle detectors, and UV and IR spectroscopic imagers. Observations are made in two primary orientations, one for gravity science (spacecraft spin axis and main antenna pointing to Earth), and the other for microwave atmospheric sounding (spin axis perpendicular to orbit plane to allow nadir pointing in spin plane). All other investigations work in either one or both orientations. Primary science data are collected within 3 hours of closest approach, although calibrations, occasional remote sensing, and magnetospheric observations are planned throughout the orbits. Since launch in August 2011, the Juno ops team has exercised the instruments with occasional checkouts, periodic maintenance, compatibility tests, and an Earth Flyby in October 2013 (Figure 1). This paper discusses lessons learned from using the instruments and from challenges faced as a result of anomalies, with an emphasis on applications to orbital operations. It also focuses on mission plan details for the science orbits as well as on key work and remai- ing decisions, including recent evaluation of trajectory alternatives for the initial large capture orbit and primary science orbits, and preliminary development of a tactical playbook to facilitate contingency response in the orbital mission.