Thermospheric Variations From GNSS and Accelerometer Measurements on Small Satellites

Monitoring and understanding geophysical processes in the thermosphere is primordial for space physics, low Earth orbiters, and ground-based technologies. In the last half century, thermospheric variations, anomalies, and climatology have been investigated and reported, but were limited due to lack of observations and large uncertainty in the models. Today, Global Navigation Satellite Systems (GNSS) and accelerometers on small satellites can sense neutral-density and wind variations with unprecedented accuracy, which contribute to understand thermospheric variations and improve the current empirical and physical models. In this paper, an overview of past and present developments and efforts in sensing and modeling thermospheric density and wind variations is presented, as well as the future challenges and perspectives for GNSS and accelerometers on small satellites.