Cramér–Rao Lower-Bound Optimization of Flush Atmospheric Data System Sensor Placement

Abstract

Flush atmospheric data systems take measurements of the pressure distribution on the forebodies of vehicles and improve the estimate of freestream parameters during reconstruction. These systems have been present on many past entry vehicles, but design of the pressure transducer suites and the placement of the sensors on the vehicle forebody have largely relied on engineering judgment and heuristic techniques. This paper develops a flush atmospheric data system design methodology using Cramér–Rao lower-bound optimization to define the smallest theoretical variance possible from the estimation process. Application of this methodology yields Pareto frontiers of possible optimal configurations and identifies the number of ports that serve as the point of diminishing returns. The methodology is tested with a simulated Mars entry, descent, and landing trajectory.