Ganymede (moon) be launched in 2024, though this schedule might be revised and aligned with JUICE. A Ganymede orbiter based on the Juno probe was proposed in 2010 for the Planetary Science Decadal Survey. Possible instruments include Medium Resolution Camera, Flux Gate Magnetometer, Visible/NIR Imaging Spectrometer, Laser Altimeter, Low and High Energy Plasma Packages, Ion and Neutral Mass Spectrometer, UV Imaging Spectrometer, Radio and Plasma Wave sensor, Narrow Angle Camera, and a Sub-Surface Radar. Another canceled proposal to orbit Ganymede was the Jupiter Icy Moons Orbiter. It was designed to use nuclear fission for power, ion engine propulsion, and would have studied
Orbit or within that planet. Owing to mutual gravitational perturbations, the eccentricities of the planetary orbits vary over time. Mercury, the smallest planet in the Solar System, has the most eccentric orbit. At the present epoch, Mars has the next largest eccentricity while the smallest orbital eccentricities are seen with Venus and Neptune. As two objects orbit each other, the periapsis is that point at which the two objects are closest to each other and the apoapsis is that point at which they are the farthest. (More specific terms are used for specific bodies. For example, "perigee" and "apogee" are the