Periodic Reporting for period 1 - E.T.COMPACT (COMPACT AND PROPELLANT-LESS ELECTRODYNAMIC TETHER SYSTEM BASED ON IN-SPACE SOLAR ENERGY)
Reporting period: 2024-10-01 to 2025-09-30
E.T.COMPACT is aimed at reaching technology readiness level four for three in-space technologies on the domain of solar energy harvesting and green propulsion. The first technology, a thin film 2-terminal tandem CIGS/Perovskite module with efficiency larger
than 15% and a power-per-weight ratio larger than 50W/kg, is called to reduce the cost of in-space solar panels. The second technology is a miniaturized (target volume 3U) green-propulsion mobility module device based on an electrodynamic tether.
Designed to have tether reel-in/reel-out capability and equipped with a field emission cathode, the mobility module can use the harvested in-space solar energy to produce propulsion (both thrust and drag) without using propellant. For the mobility
module, and the satellite platform to host it, research on ultralight structures based on 3D printed compliant polymeric techniques is conducted. Besides mass reduction, the goal is to integrate compliance mechanisms for both tether deployment and thin-film solar
panel unfolding. The third technology, which combines the experience and knowledge of the consortium on photovoltaic and tether technologies, is a novel bare-photovoltaic tether that uses the metallic tape tether for both electron collection and as the back
contact of tandem CIGS/Perovskite modules. It integrates in a single device solar energy harvesting and propellant-less propulsion. Project impact is enhanced by activities on market analysis, unit mass production, and early commercialization, solidly supported by
simulation work to assess the use of these technologies in the field of post mission disposal, active debris removal, in-orbit servicing and space tugs.
than 15% and a power-per-weight ratio larger than 50W/kg, is called to reduce the cost of in-space solar panels. The second technology is a miniaturized (target volume 3U) green-propulsion mobility module device based on an electrodynamic tether.
Designed to have tether reel-in/reel-out capability and equipped with a field emission cathode, the mobility module can use the harvested in-space solar energy to produce propulsion (both thrust and drag) without using propellant. For the mobility
module, and the satellite platform to host it, research on ultralight structures based on 3D printed compliant polymeric techniques is conducted. Besides mass reduction, the goal is to integrate compliance mechanisms for both tether deployment and thin-film solar
panel unfolding. The third technology, which combines the experience and knowledge of the consortium on photovoltaic and tether technologies, is a novel bare-photovoltaic tether that uses the metallic tape tether for both electron collection and as the back
contact of tandem CIGS/Perovskite modules. It integrates in a single device solar energy harvesting and propellant-less propulsion. Project impact is enhanced by activities on market analysis, unit mass production, and early commercialization, solidly supported by
simulation work to assess the use of these technologies in the field of post mission disposal, active debris removal, in-orbit servicing and space tugs.
Trade-off analysis work was carried out to analyse different design options for the GMM. Different tether geometries were considered, solutions for the deployment mechanism and cathodes. A set of requirements was prepared for the GMM and all its elements. A GMM based on a tape-like ET, single reel deployment with reel-in/out capability, and an expellant-less cathode was chosen. A design of the GMM was prepared as well as a design of a fully autonomous 6U platform that could host the GMM in a future in-orbit demonstration.
The requirements and specifications were developed for a rollable BPT demonstrator. The core activities in attaining a tangible and fully functional BPT have been started and the focus at the current stage is the development of all the necessary sub-processes. A series of handling, additive and subtractive process steps are under development. Focus of the first year has been the back contacting of the PV-submodules, the development of cutting and stacking process for the PV-submodules and the precise web handling of the metallic substrate. These process steps are designed in such a way that concatenation of these processes is possible and hence a precise and robust fabrication of rollable BPTs can be attained.
Key progress was done in the development of a 15 cm² tandem PVK/CIGS two-terminal thin-film solar cells with a power conversion efficiency (PCE) exceeding 15% and a power-to-weight ratio above 50 W/kg. Wide-band-gap perovskites (1.63–1.64 eV) with efficiencies up to 17% on small-area devices were prepared. The fabrication of minimodule prototypes with reliable voltage generation through picosecond laser scribing confirms the feasibility of transferring laboratory-scale architectures to interconnected modules. A prototype minimodule (~10 cm²) was fabricated with a semi-transparent architecture, incorporating blade-coated PTAA and triple-cation perovskite absorbers. The initial two-terminal rigid tandem devices, combining perovskite and CIGS, were fabricated on a glass substrate.
The requirements and specifications were developed for a rollable BPT demonstrator. The core activities in attaining a tangible and fully functional BPT have been started and the focus at the current stage is the development of all the necessary sub-processes. A series of handling, additive and subtractive process steps are under development. Focus of the first year has been the back contacting of the PV-submodules, the development of cutting and stacking process for the PV-submodules and the precise web handling of the metallic substrate. These process steps are designed in such a way that concatenation of these processes is possible and hence a precise and robust fabrication of rollable BPTs can be attained.
Key progress was done in the development of a 15 cm² tandem PVK/CIGS two-terminal thin-film solar cells with a power conversion efficiency (PCE) exceeding 15% and a power-to-weight ratio above 50 W/kg. Wide-band-gap perovskites (1.63–1.64 eV) with efficiencies up to 17% on small-area devices were prepared. The fabrication of minimodule prototypes with reliable voltage generation through picosecond laser scribing confirms the feasibility of transferring laboratory-scale architectures to interconnected modules. A prototype minimodule (~10 cm²) was fabricated with a semi-transparent architecture, incorporating blade-coated PTAA and triple-cation perovskite absorbers. The initial two-terminal rigid tandem devices, combining perovskite and CIGS, were fabricated on a glass substrate.
The theoretical studies conducted in the project on the performance of spinning electrodynamic tethers highlighted the disroptuve potential that this propellant-less technology has in the space propulsion arena and, consequently, in applications like postmission disposal, space tugs, active debris removal and in-orbit servicing. Regarding the bare-photovoltaic tether, it is a device that combines electrodynamic and photovoltaic technologies to provide propulsion and power in a single device. Key needs after E.T.COMPACT includes increasing the TRL up to a flight model and the implementation of an in-orbit demonstration of the technologies.
The lightweight, modular 3D-printed compliant structure will decrease structure weight and free up capacity for payload. This can lengthen mission duration, support larger scientific instruments, or facilitate access to more costly launch slots. This is particularly relevant because approximately 2380 cubesats in the 6-16U range will be launched over the next five years. The market demands innovation in small satellite structures as decreasing satellite size makes volume constraints more critical than mass constraints. Routing cables between boards, sensors, and deployable elements becomes challenging, error-prone, and time-consuming and a 3D-printed compliant structures can simplify supply chains while providing flexibility in design.
The cathode being developed by TUD Dresden is a key element or the GMM and and also relevant for small scale satellites, due to their limited power, mass, and volume budget. Spacecraft require means to control their electric potential in reference to the atmospheric plasma, for which the here-developed cathode could be implemented. With some adjustments, the use for electrostatic sails or miniature ion thrusters can be another relevant application. The detailed comparison of different electron emitter technologies along with other application-oriented results is of interest for the electron emitter research community.
The deployment of PVK-based tandem devices in a two-terminal monolithic configuration addresses several key limitations of the current state of the art. In contrast to the more mature four-terminal architectures, the two-terminal approach minimizes optical parasitic absorption and reduces the need for external interconnections. Achieving a high-efficiency, large-area (≥15 cm²) flexible tandem module with PCE exceeding 15% would constitute a significant advancement over existing proof-of-concept demonstrations, which remain confined to laboratory-scale devices (<2 cm²).
The R+D in respect to CIGS optimisation can be transferred/optimised for novel applications that need a good efficiency under NIR illumination, such us tandem devices, luminescent solar concentrators and for wireless power transmission. The knowledge gain and expertise for a fabrication process for a flexible and elongated PV array have an impact on several use cases: Terrestrial applications for the rollable Tether could be in specialised BIPV applications with a similar form factor like the tether (PV shading systems, luminescent solar concentrators integrated into windows).
The lightweight, modular 3D-printed compliant structure will decrease structure weight and free up capacity for payload. This can lengthen mission duration, support larger scientific instruments, or facilitate access to more costly launch slots. This is particularly relevant because approximately 2380 cubesats in the 6-16U range will be launched over the next five years. The market demands innovation in small satellite structures as decreasing satellite size makes volume constraints more critical than mass constraints. Routing cables between boards, sensors, and deployable elements becomes challenging, error-prone, and time-consuming and a 3D-printed compliant structures can simplify supply chains while providing flexibility in design.
The cathode being developed by TUD Dresden is a key element or the GMM and and also relevant for small scale satellites, due to their limited power, mass, and volume budget. Spacecraft require means to control their electric potential in reference to the atmospheric plasma, for which the here-developed cathode could be implemented. With some adjustments, the use for electrostatic sails or miniature ion thrusters can be another relevant application. The detailed comparison of different electron emitter technologies along with other application-oriented results is of interest for the electron emitter research community.
The deployment of PVK-based tandem devices in a two-terminal monolithic configuration addresses several key limitations of the current state of the art. In contrast to the more mature four-terminal architectures, the two-terminal approach minimizes optical parasitic absorption and reduces the need for external interconnections. Achieving a high-efficiency, large-area (≥15 cm²) flexible tandem module with PCE exceeding 15% would constitute a significant advancement over existing proof-of-concept demonstrations, which remain confined to laboratory-scale devices (<2 cm²).
The R+D in respect to CIGS optimisation can be transferred/optimised for novel applications that need a good efficiency under NIR illumination, such us tandem devices, luminescent solar concentrators and for wireless power transmission. The knowledge gain and expertise for a fabrication process for a flexible and elongated PV array have an impact on several use cases: Terrestrial applications for the rollable Tether could be in specialised BIPV applications with a similar form factor like the tether (PV shading systems, luminescent solar concentrators integrated into windows).