Master's Thesis Defense

Brendan Mindiak

(Advisor: Prof. Ahuja and Prof. Whorton)

Improving the Efficiency and Accuracy of Landing Site Error Calculations for Re-Entry Vehicles

Monday, November 4 

3:00 p.m.

Engineering Science and Mechanics (ESM) 108

Abstract
Space missions that involve atmospheric re-entry require thorough landing site analysis for mission safety and success. Monte Carlo simulations are frequently utilized to analyze the uncertainty in the landing site caused by atmospheric conditions that may fluctuate during re-entry, but require time on the order of hours to complete the analysis. Thus, the need arises for a more efficient process that maintains a high computational accuracy. To meet this need, reference tables are generated that allow for a user to look up the landing site uncertainty given a set of re-entry conditions. These tables are generated by transforming a traditional re-entry state vector to a modified state vector that contains the magnitude of the re-entry velocity, three angles, and the vehicle’s ballistic coefficient. Then a Monte Carlo simulation is performed for each feasible set of re-entry conditions. A table is first generated for ballistic, non-ablative re-entry vehicles that have no flight control system. Then, a simple propulsive control system is implemented to observe how the control system impacts the resulting landing uncertainty. To improve the applicability of these tables, an inverse-distance weighting interpolation scheme is employed that utilizes the table entries to determine the landing error for any set of re-entry conditions that a user may provide. Comparing this interpolation to a standard Monte Carlo simulation, it is observed that both methods achieve similar results, but the interpolation method requires less than one second compared to the hour required for a standard Monte Carlo simulation. Thus, the work presented in this thesis represents the first intuitive and computationally inexpensive method to determine landing site error without sacrificing the fidelity of the results.

Committee

• Prof. Krish Ahuja – GTRI and School of Aerospace Engineering (advisor)
• Prof. Mark Whorton – GTRI and School of Aerospace Engineering (co-advisor)
• Prof. John Dec – School of Aerospace Engineering