Neptune Aerocapture Systems Analysis

Abstract

A Neptune Aerocapture Systems Analysis is completed to determine the feasibility, benefit and risk of an aeroshell aerocapture system for Neptune and to identify technology gaps and technology performance goals. The high fidelity systems analysis is completed by a five center NASA team and includes the following disciplines and analyses: science; mission design; aeroshell configuration screening and definition; interplanetary navigation analyses; atmosphere modeling; computational fluid dynamics for aerodynamic performance and database definition; initial stability analyses; guidance development; atmospheric flight simulation; computational fluid dynamics and radiation analyses for aeroheating environment definition; thermal protection system design, concepts and sizing; mass properties; structures; spacecraft design and packaging; and mass sensitivities.Results show that aerocapture can deliver 1.4 times more mass to Neptune orbit than an all-propulsive system for the same launch vehicle. In addition aerocapture results in a 3-4 year reduction in trip time compared to all-propulsive systems. Aerocapture is feasible and performance is adequate for the Neptune aerocapture mission. Monte Carlo simulation results show 100% successful capture for all cases including conservative assumptions on atmosphere and navigation. Enabling technologies for this mission include TPS manufacturing; and aerothermodynamic methods and validation for determining coupled 3-D convection, radiation and ablation aeroheating rates and loads, and the effects on surface recession. Symbols/Nomenclature

Prediction of the Aerothermodynamic Environment of the Huygens Probe

“…Mars Pathfinder 8 , Mars Exploration Rover 9 , Genesis 10 ) as well as numerous system studies (e.g. aerocapture at Neptune 11 and Titan 12 ). The POST2 simulation method was used in a Monte Carlo analysis of the Huygens probe entry, descent, and impact at Titan.…”

Titan Explorer: The Next Step in the Exploration of a Mysterious World

“…A fall back to the units planned for delivery in 2009 could be accepted, however, there would be a significant performance penalty. 4 Demonstration of aerocapture The first use of aerocapture should not be on a flagship class mission. If aerocapture has not been demonstrated by about 2013, then either the launch date should be delayed, or the Titan Explorer will have to shift to an all propulsive system, or Titan Explorer will have to bear the technology demonstration flight.…”

“…An overview of the results from previous studies is provided to illustrate the essential attributes of aerocapture (ref. 4). Aerocapture analysis for this study was limited to assessing minor system impacts (TPS and propellant mass) due to an increase in the system mass.…”

Preliminary Convective-Radiative Heating Environments for a Neptune Aerocapture Mission

“…Aerocap-β m C D A ( ) ⁄ = ture can result in large mass savings in comparison to propulsive deceleration. For this study a reference mission concept 1 was developed for a 2017 launch with a 10 year transit to Neptune of an orbiter designed for a scientific investigation of Neptune and its moon Triton. For the reference mission guidelines, it was determined that the mass savings resulting from an aerocapture maneuver would be necessary to deliver the required payload.…”

“…Computational analyses of the convective and radiative aeroheating environments which the vehicle would experience are detailed herein, and results from other disciplines are presented in several companion papers [1][2][3][4][5] .…”