Analysis of communication blackout mitigation in Martian atmospheric entry with active MHD flow control systems
Creators: name:  V. GIANGASPERO 
name:   V. SHARMA 
name:   L. JOHANNES 
name:   J. THOEMEL 
name:   A. LANI 
name:   S. POEDTS 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: FUTURE SPACE OPERATIONS

description: Atmospheric entry represents one of the most critical phases of a space mission. The safety of the expensive payload strongly depends on the spacecraft survival to the harsh conditions experienced during the hypersonic descent into the target planetary atmosphere, characterised by high thermal loads on the vehicle surface. In addition, flight at hypersonic speed generates a plasma layer around the vehicle, leading to a disruption of the communication system during the crucial terminal phase of a space mission. The formation of entry plasma prevents radio signals to be received and transmitted from spacecraft, leading to a communication blackout, which can last several minutes, endangering the whole mission and deeply affecting crew or payload safety. The current aerospace technology requires further investigations and investments to overcome these two problems, especially considering the recent renewed interest in future human missions to colonise the space system. As of today, the reduction of thermal loads on spacecraft is based on physical expensive, heavy, and non-reusable thermal protection systems (TPS). For human exploration missions, such as Mars exploration, the use of such physical TPS greatly increases the design effort and cost of the spacecraft and reduces the cost efficiency of the mission by sacrificing payload mass for such systems.Regarding communication blackout, on the other hand, spacecraft solely rely on satellite constellations to communicate through the plasma wake, partially reducing the telecommunication blackout period, but with no active system dedicated to this issue. As previously demonstrated with theoretical, experimental and numerical studies, Magnetohydrodynamics (MHD) provides a framework for tackling both issues affecting atmospheric entry: in principle, high enough electromagnetic (EM) fields can be used to reduce heat fluxes (as a consequence of modifying bow shock standoff distance and shock layer structure) and create a magnetic windowing able to mitigate the blackout. This work presents a numerical tool to analyse the effect of the application of MHD flow control systems for atmospheric entry flights. Numerical Computational Fluid Dynamics (CFD) simulations will be performed at different trajectory points for an hypersonic entry in Martian atmosphere. Different simulation of flow/electromagnetic coupling will be performed with the COOLFLuiD solver which is based on a three dimensional, finite volume, unstructured grid framework. The study will be useful for evaluating potential benefits for communication blackout in hypersonic flight with electromagnetic field imposed from an onboard device. The interaction between the electromagnetic waves and the ionised plasma around the vehicle will be analysed by the application of an optical ray tracing method. The use of an advanced blackout analysis method capable of reproducing more complex waves phenomena, such as reflection, refraction and phase modulation, has the advantage of improving the overall understanding of the complex physical phenomena involved in the blackout problem. A comparison between different configurations of MHD control at different entry conditions will be performed to asses the benefits of magnetic windowing on the communication systems. The final goal is to present a numerical methodology capable to investigate the impact of electromagnetic fields for reducing surface thermal heat loads and communication blackout, opening up promising perspectives for the future generation of spacecraft.