Researchers refine tether technologies for commercial use
By Sven Bilén|December 2024
The Space Tethers Technical Committee focuses on the development and use of tether-based technology for space systems.
The space tethers community made strides toward space debris removal, more efficient orbital propulsion and deeper exoplanetary exploration.
In April, researchers at the University of Colorado at Colorado Springs designed the first mission in which a tethered spacecraft would image an exoplanet. Working with NASA’s Jet Propulsion Laboratory in California, they combined a solar gravitational lens technique with tether dynamics, allowing a spacecraft to sample the image plane of a distant planet in the optical spectrum without the need for onboard propellant for the relative motion station-keeping. Their work on tether deployment and vibration control could enhance long-duration missions for exoplanetary exploration.
In the area of debris removal, researchers at the University of Buffalo in New York, funded by the U.S. National Science Foundation, reported in January on their model of a net-based tether, with promising results in terms of safe target capture and system efficiency. In May, they overviewed their advanced control systems for robotic tether nets, using learning-aided techniques to improve target capture even under difficult conditions. Researchers at Tokyo Metropolitan University also made strides in tether- net capture technology. In February, they reported their simulations and experiments on optimal collision points for tether-net entanglement with debris. Their work, which involved modeling the net as a spring-mass-damper system, offered new strategies for debris mitigation.
Researchers at the Beijing Institute of Technology, funded by China’s National Natural Science Foundation, have developed detumbling strategies for underactuated tethered satellites. In January, they proposed a robust detumbling method based on hierarchical sliding mode control. In July, they developed a tension regulation method that’s capable of detumbling a target as well as suppressing the tether libration for active debris removal missions.
As of October, the testing campaign of the engineering qualification model of a deorbit device was nearing completion under the Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit-Fly project. Funded by the European Innovation Council, the E.T.PACK-F consortium is coordinated by the Universidad Carlos III de Madrid in collaboration with the University of Padova in Italy, the Technical University of Dresden in Germany, Spanish company SENER Aeroespacial and German startup Rocket Factory Augsburg. The team plans to fly its 12-unit, 24-kilogram deorbit device in 2025 or 2026.
In October, the Compact and Propellant-less Electrodynamic Tether System Based on In-Space Solar Energy project began, with funding from the European Innovation Council. Coordinated by Universidad Carlos III de Madrid — in collaboration with the University of Padova, the Technical University of Dresden, the Spanish company DEIMOS Engineering and Systems, Italy-based Halocell Europe and the Austrian company Sunplugged — the E.T.COMPACT project is to study thin-film two-terminal tandem Perovskite-CIGS solar cells for installation on an ultra-compact propulsion system based on bare-photovoltaic tether technology.
At the University of Strathclyde in Scotland, researchers were active on three fronts. They advanced symbolic computation programs for analyzing motorized tethers with varying mass asymmetries, building a library of code variants that can assess on-orbit performance. Work concluding in June explored miniaturizing motorized momentum-exchange tethers for raising the orbits of nanosatellites. Researchers discovered that while the technology shows promise, energy density constraints remain a limiting factor. In August, they completed an analysis of the cost savings of using a motorized tether to propel a 50-kilogram payload from low-Earth orbit.
