Feasibility and Performance Analysis of Neptune Aerocapture Using Heritage Blunt-Body Aeroshells
Athul Pradeepkumar Girija, Sarag J. Saikia, James M. Longuski, Shyam Bhaskaran, Matthew Stephen Smith, J. A. Cutts
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.