Very Low Earth Orbit (VLEO) has recently emerged as a promising operational regime, offering benefits such as reduced communication latency and improved imaging resolution. However, the elevated atmospheric density at these altitudes generates substantial aerodynamic drag, severe
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Very Low Earth Orbit (VLEO) has recently emerged as a promising operational regime, offering benefits such as reduced communication latency and improved imaging resolution. However, the elevated atmospheric density at these altitudes generates substantial aerodynamic drag, severely limiting satellite lifetime without active propulsion or drag-reduction measures. In parallel, there is growing cross-sector interest in recovering small satellites or their payloads to enable hardware reuse, reduce mission costs, and expand the scope of in-orbit experimentation.
This thesis addresses the coupled challenge of extending nano-satellite lifetime in VLEO while enabling controlled end-of-life re-entry and intact recovery. Specifically, it focuses on the aerodynamic optimization of satellite geometry for drag reduction during the orbital phase, coupled with the design of a deployable or inflatable re-entry system to ensure both thermal protection and post-reentry retrieval capability.
The heatshield design phase employed a full-factorial grid search over key geometric parameters, applied to both inflatable and deployable concepts. This stage integrated two dedicated models: an entry trajectory analysis to evaluate thermal survivability and stability, and a heatshield mass estimation model to estimate mass and center-of-gravity values. The resulting feasible design space provided the basis for subsequent aerodynamic optimization. For each surviving configuration, a custom Python-based free-molecular panel method using a Cercignani-Lampis-Lord (CLL) gas-surface interaction model was coupled with a multi-objective optimizer to minimize drag while also minimizing satellite length. The optimized designs were then evaluated using an orbital lifetime estimation model under different solar activity levels to quantify performance gains. Verification and validation were performed through cross-tool agreement with ADBSat and DSMC/DS2V for selected cases, and benchmarking against published LOFTID and ADEPT data where applicable.
From the 880 satellite-heatshield configurations evaluated, only 10 (4 inflatable, 6 deployable) met all mass, geometry, thermal, and stability constraints under uncertainty. Lifetime analysis revealed that optimized nosecones could extend orbital lifetime by up to 20%, while variations in solar activity could alter lifetime by up to a factor of three, highlighting the dominant influence of environmental conditions. Although the deployable concept was aerothermally viable, its packed configuration restricted solar array area to the point where even the most favorable geometry produced only 8W of power-an infeasible level for most nano-satellite missions. The final design therefore adopted an inflatable heatshield with the lowest achieved drag, paired with a shuttle-type solar panel layout to improve stability and further reduce drag compared to a feather configuration, at the expense of a small power reduction. Additionally, the need for aerodynamic control during re-entry was identified to reduce the landing footprint to a feasible size.
These results demonstrate the feasibility of integrating aerodynamic optimization with re-entry system design to meet both lifetime extension and safe recovery objectives for nano-satellites in VLEO. While the optimized inflatable configuration achieved significant lifetime gains and robust thermal protection, further work is required to implement aerodynamic control for footprint reduction and to experimentally validate the choice of GSI parameters.
Overall, the work demonstrates a coherent design pathway to reconcile drag minimization in orbit with high-drag requirements at re-entry, and provides a validated, computationally efficient framework for early-phase VLEO mission design with recovery capability.
