Enhancements to ADBSat: Implementation and verification of dynamic accommodation coefficient models

Abstract

This work was motivated by the need to have accurate accommodation coefficient models in the ADBSat (Aerodynamic Database for Satellites) software. The current state of ADBSat software relies on generating aerodynamic databases for objects using fixed accommodation coefficients as input from the user, which doesn't consider the change in accommodation coefficient with the environmental changes. In this work, two dynamic accommodation coefficient models were implemented in the ADBSat software. The added dynamic accommodation coefficient functions complement ADBSat software and work on the same input the software requires to compute the aerodynamic coefficients for objects. The newly implemented dynamic accommodation coefficient model functions were verified and compared against an existing tool, the Vehicle Environment Coupling and TrajectOry Response (VECTOR) tool. The accommodation coefficient values generated from ADBSat agreed with the results generated using the VECTOR tool with a maximum error of less than 0.7\%. Finally, the newly implemented SESAM function was used in the ADBSat software to generate drag coefficients and derived density estimates for three satellite missions: GOCE(Gravity field and steady-state Ocean Circulation Explorer), CHAMP(CHAllenging Minisatellite Payload) and GRACE(Gravity Recovery And Climate Experiment), these results were compared with the results from ADBSat with fixed accommodation coefficient. Finally, The derived density estimates from ADBSat were compared to the NRLMSISE-00 (Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Exosphere) atmospheric density model estimates. ADBSat results with the SESAM provided better agreement with the NRLMSISE-00 in the GOCE and the CHAMP datasets, while for the GRACE dataset, fixed accommodation results provided better agreement with the NRLMSISE-00. The newly added dynamic accommodation coefficient models give spacecraft designers and analysts more accurate tools to model spacecraft aerodynamics and make better-informed decisions in the early design stages.