Feasibility and Performance Analysis of Neptune Aerocapture Using Heritage Blunt-Body Aeroshells

Abstract

Large navigation and atmospheric uncertainties have historically driven the need for a mid-lift-to-drag-ratio vehicle with of 0.6–0.8 for aerocapture at Neptune. Most planetary entry vehicles flown to date are low- blunt-body aeroshells with less than 0.4. The lack of a heritage mid- aeroshell presents a major hurdle for Neptune aerocapture, as the development of a new entry vehicle incurs significant time and investment. Techniques that may allow Neptune aerocapture to be feasible using heritage low- blunt-body aeroshells are investigated that obviate the need for mid- aeroshells. A navigation study is performed to quantify the delivery errors, and a new guidance algorithm with onboard density estimation is developed to accommodate large atmospheric uncertainties. Monte Carlo simulation results indicate that the reduced navigation uncertainty and improved guidance scheme enable a blunt-body aeroshell with to perform aerocapture at Neptune. The expected heat rate is within the capabilities of existing thermal protection system materials.