Simulating Ionospheric Perturbations from Rocket Launches

Rocket launches cause observable perturbations in the Earth’s ionosphere. Exhaust gasses diffuse and react with ions to significantly deplete the ionosphere over large regions. Moreover, expansion of exhaust gasses can generate gravity and acoustic waves which drive travelling ionospheric disturbances. Together, these phenomena offer novel ways of detecting and characterising rocket launches. Moreover, they may cause large changes in the ionosphere with potential to adversely affect satellite communications and some radar systems.

This project will simulate effects of these disturbances on the ionosphere. This will include development of numerical methods for simulating transport of exhaust gasses and/or generation of waves in the upper atmosphere. Simulation output will be coupled to a general circulation model of the coupled ionosphere-thermosphere system.

Contact:

Dr George Bowden g.bowden@adfa.edu.au

Supervisor(s):
Dr George Bowden g.bowden@adfa.edu.au
Dr Melrose Brown melrose.brown@adfa.edu.au

Notes:

This project would extend work that has been done on modelling ionospheric effects of rocket launches. We used the Global Ionosphere Thermosphere Model (GITM), a general circulation model (GCM) of the upper atmosphere to simulate ionospheric depletion due to chemical reactions with rocket exhaust. New chemical species, reactions, and source terms were introduced to enable this modelling. We also used GITM to simulate acoustic wave propagation through addition of source terms and perturbation of boundary conditions.

While GCMs can model rocket exhaust effects on larger length and time scales (hundreds/thousands of kilometres, minutes/hours), particle-based methods are needed to capture behaviour on smaller scales (seconds, tens of kilometres). Preliminary work has been done in this area, with direct simulation Monte Carlo (DSMC) modelling of rocket plume expansion run on the NCI Gadi Cluster. Further work would consider transport of exhaust gasses in a stratified atmosphere with chemical reactions. The goal of these simulations is to provide realistic source terms for GCM simulations of ionospheric depletions and wave propagation.

A possible PhD project would develop a chain of simulations from the rocket engine to the regional scale ionosphere-thermosphere system. Computational fluid dynamics (CFD) would be used to model expansion in the rocket nozzle and in the collisional free expansion regime. This would then provide boundary conditions for an axisymmetric DSMC simulation of the exhaust plume. Subsequently, this would provide input conditions for a vertically stratified DSMC simulation of exhaust gas advection and thermalisation. Finally, a GCM simulation would be used to model the longer-term diffusion and chemical reactions of the gasses in the upper atmosphere. Simulation results would be compared with ionospheric observations from navigation satellite signals and ionosondes.

Supervisor