A Non-NEP Implementation of NASA’s “Neptune Orbiter With Probes” Vision Mission

Abstract

The “Neptune Orbiter with Probes” (NOP) mission concept is one of the 17 Vision Mission cases for study in NASA’s 2003 Vision Missions Studies NRA (NRA‐03‐OSS‐01‐VM). Its primary science goals are to provide detailed information about the composition and internal structure of the “ice giant” planet Neptune, for comparison to the gas giant planets Jupiter and Saturn. NASA selected two teams to study the mission concept, one using a Nuclear Electric Power and Propulsion (NEPP) implementation for transfer to and orbit insertion at Neptune, one using Solar Electric Propulsion (SEP) and/or gravity assist (GA) for transfer to Neptune, aerocapture for orbit insertion, and a Radioisotope Power Source (RPS) for electric power. Prof. Andy Ingersoll of Caltech is the PI of the non‐NEPP team, which includes a nine‐member science team covering the major science objectives to be addressed in the Neptune system and an engineering team with experts from Caltech, JPL and its “Team X”, and three NASA centers. Various combinations of SEP and GA yield relatively short ∼12‐year transfers to Neptune, and high Neptune approach V∞ and orbit insertion delta‐V (∼7 km/s) that is better done using aerocapture than using chemical propulsion. After probe delivery and capture into orbit, Triton, perhaps a former Kuiper Belt object, is the “tour engine” that drives a three‐year (minimum) tour, much as Cassini uses Titan. In different phases over the science mission lifetime the evolving orbit optimizes investigation of Neptune’s magnetosphere, rings, and inner satellite system, as well as structure, composition, and dynamics of the planet itself. Team X and our team members, including aerocapture experts from NASA’s Aerocapture Systems Analysis Team and students, studied ground and flight systems designs and technology needs. This paper discusses the innovative process by which the NOP mission concept was studied, the team performing the studies, science objectives, and high‐level results.