Magnetohydrodynamic power generation for planetary entry vehicles

A new concept under development at NASA, called Regenerative Aerobraking, attempts to harvest a portion of the power lost during planetary entry. One approach under investigation is magnetohydrodynamic (MHD) power generation that may possibly capitalize on the ionization created during atmospheric entry. To better study the potential of that approach, a new analysis capability was developed that combines the computational capabilities of hypersonic aerodynamics and MHD physics to model the processes in the ionized shock and boundary layers in magnetic field. This paper highlights the new analysis capability by presenting some results for a ballute geometry during hypersonic entry into the Martian atmosphere. The results show that with 1% potassium seed injected into the shock layer, MHD power generation at a level of at least several hundred kilowatts per meter of ballute circumference can be extended to flight velocities as low as 3.5 km/s (or even lower). If the total time of deceleration to 3.5 km/s is 30-40 seconds, then at least several gigajoules of energy can be generated during the ballute descent. The total amount of potassium seed required is about 50-100 kg. These findings are very encouraging for the Regenerative Aerobraking concept.