Feasibility of solar-enhanced thermoelectric generators on electrodynamic tethers for satellite deorbiting

In recent years, addressing the imperative of implementing a deorbit mechanism for satellite end-of-life scenarios has become a focal point in space studies. The E.T.Pack initiative actively contributes to this shared objective by proposing the use of an electrodynamic tether to generate a force for decelerating satellites. To achieve this, power is required to supply the electron emitter, enabling current flow through the tether. This thesis explores a method to contribute a portion of the required power by incorporating a solar thermoelectric generator (TEG) onto the tether. TEGs are solid state devices based on the Seebeck effect, generating an electric potential difference when a temperature difference is established between two plates. Various TEG configurations such as bulk, y-type and planar are evaluated. Given the orbital motion, the flexibility needed for the deployment mechanism, the low thickness, and the twisting of the tether, the planar configuration is identified as the most viable option. Two different planar TEG manufacturing methods were studied, screen printing and sputtering deposition, and different institutes were contacted to receive samples of both types. To achieve the temperature gradient in the planar configuration, strips of different optical properties are placed on the hot plate (a solar absorber with low emissivity) and on the cold plate (a solar reflector with high emissivity). This configuration ensures that the hot plate remains warmer than the cold plate, even without direct solar radiation, as it emits less heat than the cold plate. Simulations involving radiative heat transfer were conducted to assess the achievable temperature gradient, and experiments in a vacuum chamber with solar simulator were carried out to evaluate the feasibility of the concept.