Tethered Satellite System for Cross-Track Formation Flying: Architecture and Performance Analysis

This paper presents a novel tethered satellite system for Earth observation, consisting of two small satellites connected by a cross-track tether and operating in Low or Very Low Earth Orbit. The tether hosts a distributed antenna array, enabling Multi-Input Multi-Output Synthetic Aperture Radar applications. Continuous propulsion at both satellite ends maintains tether orientation and counteracts atmospheric drag, ensuring orbital stability. This configuration offers precise relative positioning, efficient power and data transfer, and simplifies operations compared to conventional formation flying. A multibody simulation framework models the tether dynamics, incorporating lumped-mass representations and external perturbations such as drag and gravity gradient. Parametric analyses assess required propulsion as a function of altitude and tether length, enabling estimations of propellant needs and mission duration. The system’s unique architecture supports low-frequency radar sounding in HF/VHF bands, exploiting phased array beamforming and cross-track aperture to enhance resolution and enable subsurface imaging, such as ice structure analysis. Results indicate that the proposed configuration provides a cost-effective, high-performance platform for Earth observation missions, combining the benefits of distributed sensing with a mechanically constrained and dynamically stable architecture.