Investigating miniaturized electrodynamic tethers for picosatellites and femtosatellites

The success of nanosatellites (1-10 kg) and the miniaturization of sophisticated low-power electronics has motivated interest in even smaller "smartphone"-sized spacecraft as either standalone spacecraft or elements in a maneuverable fleet. These spacecraft, known as picosatellites (100 g-1 kg) and femtosatellites (less than 100 g), have the potential to enable missions requiring a distributed fleet of sensor spacecraft (for example, distributed aperture, simultaneous spatial sampling, etc.). However, without some degree of propulsion capability, these spacecraft would behavemoreasanuncontrolledswarmthanasacoordinatedformation.Furthermore,lifetimeinlowEarthorbitcan belimitedforlow-massspacecraftwithhigharea-to-massratios.Thispapershowsthatarelativelyshort(fewmeters) electrodynamic tether is capable of providing picosatellites and femtosatellites with propellantless drag cancellation andeventheabilitytochangeorbitoveranaltituderangedeterminedbytheionosphericdensity,neutralatmosphere drag, and magnetic field strength and orientation. The ability of the electrodynamic tether system's anode to draw current from the Earth's ionosphere and generate thrust is estimated, and this performance is traded against the power needed to overcome atmospheric drag forces. The trade study includes the development of a system concept andmissionscenariotoevaluateelectrodynamic-tetherpropulsionsystemperformanceinlowEarthorbit,whichcan be adapted to other planets.