# A Survey of Current Operations-Ready Thermospheric Density Models for Drag Modeling in LEO Operations

## TL;DR

This paper compares publicly available thermospheric density models used for predicting satellite drag in Low Earth Orbit to help operators choose the best model for accurate trajectory predictions.

## Contribution

The paper evaluates four operations-ready thermospheric density models and compares them with US Government models for the first time publicly.

## Key findings

- DTM, JB2008, NRLMSIS 2.0, and TIE-GCM are viable alternatives to HASDM for satellite operators.
- Comparisons show differences in performance, computation time, and required inputs among the models.
- HASDM and WAM-IPE nowcast and forecast density comparisons are revealed for the first time publicly.

## Abstract

In Low Earth Orbit (LEO), atmospheric drag is the largest contributor to trajectory prediction error. The current thermospheric density model used by the Combined Space Operations Center (CSpOC) in operations is the High Accuracy Satellite Drag Model (HASDM). Since HASDM is not available for use outside of the US Government, satellite operators are left to determine what publicly available, open-source density model they should integrate into their internal operational software. Given the ever more challenging nature of operations in LEO, it is imperative for satellite operators to update legacy density models to a state-of-the-art density model to provide improved trajectory predictions for collision risk assessment and vital day-to-day operational decisions. This article outlines four operations-ready thermospheric density models, describing their performance, computation time, required space weather inputs, and notes for implementation. Operations-ready models include the Drag Temperature Model (DTM), the Jacchia-Bowman 2008 (JB2008) model, the US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter radar 2.0 (NRLMSIS 2.0) model, and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). US Government operational density models, HASDM and the Whole Atmosphere Model and Ionosphere Plasmasphere Electrodynamics (WAM-IPE) model, are included for comparison. Models are evaluated against global HASDM density and local GRACE-FO satellite accelerometer densities and Swarm mission densities. Additionally, comparisons between HASDM and WAM-IPE nowcast and forecast density are revealed for the first time publicly.

The online version contains supplementary material available at 10.1007/s40295-025-00558-8.