The µPET Propulsion System:
Propellantless Electrodynamic Tether Propulsion for Microsatellites

TUI is currently developing a propulsion system called the "Microsatellite Propellantless Electrodynamic Tether (µPET™) Propulsion System" that will provide propulsive capabilities to microsatellites and other small spacecraft without consuming propellant.

Fig. 1. The microPET Propulsion System concept of operations.

Fig. 2. Deployment test of the microPET tether.

How It Works:
Electrodynamic tethers can provide long-term propellantless propulsion capability for orbital maneuvering and stationkeeping of small satellites in low-Earth-orbit. The µPET™ Propulsion System is a small, low-power electrodynamic tether system designed to provide long-duration boost, deboost, inclination change, and stationkeeping propulsion for small satellites. Because the system uses electrodynamic interactions with the Earth's magnetic field to propel the spacecraft, it does not require consumption of propellant, and thus can provide long-duration operation and large total delta-V capability with low mass requirements. Furthermore, because the µPET™ system does not require propellant, it can easily meet stringent safety requirements such as are imposed upon Shuttle payloads. In addition, the tether system can also serve as a gravity-gradient attitude control element, reducing the ACS requirements of the spacecraft.

The mass, size, and power requirements of the µPET™ Propulsion System depends upon the size of the satellite and the propulsive mission. TUI has developed a prototpye of a µPET™ sized for a 125 kg microsatellite which could raise the orbit of this satellite from a 350 km drop-off orbit to a 700 km operational orbit within 50 days.

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