Localized In-Situ Density Measurement in Low Earth Orbit via Drag Torque Estimation

Fitzgerald, Riley; Cahoy, Kerri

doi:10.2514/1.a34338

Cited by 5 publications

References 10 publications

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Numerical analysis of inlet flows at different altitudes in the upper atmosphere

Jin,

Cheng,

Huang

et al. 2023

Physics of Fluids

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A comprehensive numerical study is performed to investigate gas flows inside the inlet of an atmosphere-breathing electric propulsion (ABEP) system operating in the upper atmosphere ranging from 120 to 300 km using the direct simulation Monte Carlo method. Gas pressure, mass flux, and aerodynamic drag are analyzed in depth in order to gain a deep understanding of the effects of operation altitude and the assumption of free molecular flow (FMF) on gas flows within the inlet. Computational results show that both the gas pressure and mass flux in the compression and ionization sections decrease with increasing altitude, indicating weaker compression and collection performances at higher altitudes. Therefore, careful attention should be paid to compression and collection performances of the inlet when it operates at higher altitudes. At altitudes smaller than 180 km, gas flows within the inlet are fully or partly characterized by transitional flows, so the FMF assumption tends to overestimate the gas pressure and underestimate the mass flux within the inlet resulting from the neglect of the collisions between the oncoming and reflected molecules. However, FMFs predominate within the inlet and even fill the entire inlet at altitudes larger than 180 km, so it is fairly reasonable to assume an FMF in the aerodynamic design of the inlet of an ABEP system.

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Numerical analysis of inlet flows at different altitudes in the upper atmosphere

Jin,

Cheng,

Huang

et al. 2023

Physics of Fluids

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Differential Drag Maneuvers for 6U CubeSat Separation: Enabling Space Based Radio Interferometry Observation from Small Satellite Platforms

Skelton

Weatherwax

Knapp

et al. 2022

2022 IEEE Aerospace Conference (AERO)

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Impact Angle Guidance Using Computationally Enhanced State-Dependent Differential Riccati-Equation Scheme

Lin

Yeh

et al. 2023

Journal of Spacecraft and Rockets

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This study considers the latest three-dimensional impact angle guidance based on the state-dependent differential Riccati-equation (SDDRE) scheme, and it presents novel theories that efficiently guarantee the SDDRE’s applicability and largely reduce the computational burden. The unified applicability analysis completely categorizes the state space in terms of a simple equivalent condition, where all the inapplicable cases (leading to implementation breakdowns) are newly discovered and efficiently resolved. The condition almost removes the tedious online checking routine, which accounts for the dominant effort as endorsed by complexity analysis and practical validations. Moving forward to a general scope, we analyze the computational complexity of such an SDDRE controller: first subject to the MATLAB® framework and then the state-of-the-art enhancements, where the latter come from the best performance among extensive trials. Finally, numerical and hardware experiments (notably, microcontroller and field-programmable gate array) strengthen the confidence in the analytical findings, and they enrich the value in robustness and generality that benefit more guidance or control systems.

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Localized In-Situ Density Measurement in Low Earth Orbit via Drag Torque Estimation

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Cited by 5 publications

References 10 publications

Numerical analysis of inlet flows at different altitudes in the upper atmosphere

Numerical analysis of inlet flows at different altitudes in the upper atmosphere

Differential Drag Maneuvers for 6U CubeSat Separation: Enabling Space Based Radio Interferometry Observation from Small Satellite Platforms

Impact Angle Guidance Using Computationally Enhanced State-Dependent Differential Riccati-Equation Scheme

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