Impact of Dissociation on Modeling for Plasma Aerocapture

Abstract

Interplanetary missions require changes in velocity to travel along planned trajectories, make course corrections, and for planetary capture. When performed using traditional propulsive methods, the mass and monetary costs increase exponentially as the total sum of the necessary velocity change increases. Magnetoshell Aerocapture (MAC) is an experimental technology that has mission-enabling potential, especially for the outer edges of the solar system, mainly because it reduces the costs associated with creating the changes in velocity needed for orbital insertion, through reductions in mass. It works by entraining the neutral population from the atmosphere within a plasma dipole. Through this transfer of mass and energy, the momentum of the neutrals is transferred to the spacecraft, effectively creating a drag force. Previous models for MAC have explored the plasma chemistry reactions within this process, and the resulting power transfer for ionization and charge exchange, where four populations (ions, electrons, stream neutrals, and secondary neutrals) were considered. Here an expanded model is presented where dissociation is additionally considered and the resulting seven populations are included. Results show that the inclusion of dissociation expands the amount of power being captured from the neutral atmospheric stream by the dipole. Additionally, at lower temperatures, there is a secondary peak power transfer within the system. Together, these findings imply that previously determined regions of operation within a planet's atmosphere for a spacecraft using MAC could be more extensive than expected.