Geomagnetic Storm Risks to Air-Breathing Electric Propulsion Missions

Geomagnetic storms can cause significant and rapid increases in atmospheric density at very low Earth orbit (VLEO) altitudes potentially putting a VLEO spacecraft into an un-recoverable orbit. Air-breathing electric propulsion (ABEP) spacecraft may be more susceptible to geomagnetic storms due to the low thrust-to-drag chosen for many proposed spacecraft. For ABEP missions to become viable, risks due to geomagnetic storms must be mitigated. This work explores geomagnetic storm risks to ABEP spacecraft using an orbit propagator. Spacecraft with low ballistic coefficient and low thrust-to-drag are identified as highly susceptible to geomagnetic storm risks. Two risk mitigation strategies are investigated for these space-craft: (1) preemptive orbit raising ahead of a storm, and (2) using onboard xenon propellant to increase thruster performance during a storm. An orbit propagator is used to investigate performance of these risk mitigation strategies during a G4 (severe) geomagnetic storm in November 2004. It is shown that preemptive orbit raising successfully mitigates geomagnetic storm risks for spacecraft with higher thrust-to-drag while adding a relatively small amount of xenon propellant mitigates geomagnetic storm risk for all spacecraft.