Satellite Drag Physical Model Module for a Near Real Time Operation Test Bed

ABSTRACT: The Air Force seeks to improve the accuracy of orbit specification and of 72-h orbit predictions beyond present capabilities. Thermospheric neutral density and satellite ballistic coefficient strongly impact satellite drag estimation, which is a leading source of error in orbit predictions in LEO. The goal of this Phase II project is to develop a satellite drag specification capability that will outperform the current JB08 and HASDM models. To address the proposal objectives, we propose to: a) Use full-physics models (TIMEGCM, CTIPe, and TIEGCM) to improve thermospheric density and wind forecasting to better capture storms and other anomalous conditions affecting satellite drag predictions. b) Use ensemble assimilation and dynamic tuning of model boundary conditions to produce best solutions of satellite drag and improved forecasting capability. c) Use state-of-the art forecast models, measurements, and indices for specifying solar, geomagnetic, and lower boundary conditions 72 hours in the future. d) Utilize multiple state of the art full-physics, independently assimilated, models in a super-ensemble framework to provide skill scores of drag and density predictions. Phase II deliverables include: (a) Comprehensive nowcast and forecast system for the thermosphere and satellite drag (Atmospheric Density Assimilation Model, or ADAM); (b) Model Evaluation and Validation Estimate (EVE). BENEFIT: At the end of the proposed Phase-II work, we will have a number of important accomplishments. In particular, we will have developed and validated a state-of-the-art atmospheric density and aerodynamic drag nowcast and forecast system based on three first-principles full-physics models and data assimilation techniques. The proposed ADAM framework will improve neutral density nowcast accuracy by 13-18% RMS over the Jacchia Bowman 2008 (JB08) model and 8%-12% over the High Accuracy Satellite Drag Model (HADSM) and will provide neutral density forecasts within 5% over a 72 hour period, a requirement not currently met with the present prediction models. The Phase II effort will bring together subject matter experts in atmospheric modeling, data assimilation, and satellite drag to develop an operational full-physics assimilative code for neutral density and satellite drag nowcast and forecast. The ADAM system will benefit commercial satellite operators for their own risk-mitigation exercises, including the reduction of the prediction errors of satellite positions. Primary areas for applications include satellite orbit determination, space hazard avoidance, SSA, and post-flight space-based science data analysis.