Toward Accurate Physics‐Based Specifications of Neutral Density Using GNSS‐Enabled Small Satellites

Satellite‐atmosphere interactions cause large uncertainties in low‐Earth orbit determination and prediction. Thus, knowledge of and the ability to predict the space environment, most notably thermospheric mass density, are essential for operating satellites in this domain. Recent progress has been made toward supplanting the existing empirical, operational methods with physics‐based data‐assimilative models by accounting for the complex relationship between external drivers such as solar irradiance, Joule, and particle heating, and their response in the upper atmosphere. Simultaneously, a new era of CubeSat constellations is set to provide data with which to calibrate our upper‐atmosphere models at higher spatial resolution and temporal cadence. With this in mind, we provide an initial method for converting precision orbit determination solutions from global navigation satellite system enabled CubeSats into timeseries of thermospheric mass density. This information is then fused with a physics‐based, data‐assimilative technique to provide calibrated model densities. Plain Language Summary Satellites with heights below 1,000 km (or about 600 miles) travel through the upper atmosphere, which influences the path of their orbits. This influence has been monitored in, some capacity, since the first man‐made orbiting satellites were launched into space, but predicting the effects is still quite difficult. Now commercial satellite “mega constellations” are being launched into the region at a fast pace, which means that all satellite paths must be known and projected into the future with great accuracy in order to avoid high‐speed collisions. Using Global Positioning System signals, this work blends information from tracking the position of the mega‐constellation satellites themselves with a high‐fidelity model of the upper atmosphere, in an attempt to improve our knowledge of where satellites are and where they are going to be. Key Points Global navigation satellite system‐enabled satellites are capable of monitoring the state of the thermosphere at much higher cadences than current operational datasets We present an initial technique to infer neutral densities from orbit determination products of the Spire CubeSat constellation Densities are used to drive a data‐assimilative, physics‐based model of the thermosphere and ionosphere during September 23–December 9, 2018