Session
Session V: Orbital Debris, SSA & STM
Location
Utah State University, Logan, UT
Abstract
The increasing utilization of small satellites in Low Earth Orbit (LEO) facilitates ground-breaking opportunities including telecommunication, Earth observation, gravimetry, Space Situation Awareness (SSA) and atmospheric science. However, it also creates a challenge for space debris mitigation and space traffic management. Current numerical tools predicting satellite demisability during uncontrolled atmospheric entry lack accurate models, hindering the estimation of component survivability which is needed for a sustainable growth in orbital commercialization. The University of Stuttgart’s Institute of Space Systems, together with the small satellite student society KSat e.V., addresses this issue with an interdisciplinary satellite re-entry analysis. This includes in-situ measurements in the early phase of re-entry with the Stuttgart Operated University CubeSat of Evaluation and Education (SOURCE), a 3+ Unit CubeSat scheduled for launch in 2025. The payload contains sensors for pressure, temperature, heat flux and atomic oxygen measurements during the early phase of re-entry at altitudes above 130 km. Iridium communication ensures a ground station-independent data downlink. Furthermore, numerical simulations with SCARAB (Hyperschall Technologie Göttingen, HTG) and PICLas (University of Stuttgart, IRS) including analysis for free molecular and continuous flow regimes identify critical components and points of interest in the trajectory. The demisability analysis is completed with plasma wind tunnel experiments. The plasma wind tunnel used for the tests at the University of Stuttgart is PWK1, which utilizes the self-field magnetoplasmadynamic plasma generator RD5 to create high-enthalpy air flows relevant for re-entry emulation. Three distinct trajectory points at different altitudes have been identified as test environments for the component tests, where relevant demise processes take place according to the numerical simulation results. An 80 mm diameter heat flux-pitot pressure probe was used to characterize the high-enthalpy flow, which emulates stagnation point conditions of the discrete trajectory points with focus on mass specific enthalpy and total pressure. The following components were selected as potential hard-to-demise components of SOURCE: The S-Band antenna, magnetorquers, printed circuit boards, a Carbon Fibre Reinforced Polymer (CFRP) sandwich structure, titanium rods, a camera, and batteries. Moreover, an experiment was conducted with a mock-up of SOURCE including functioning sensor arrays in a very low enthalpy environment to verify and investigate the reaction time of the in-situ measurements. All experiments are monitored with a linear pyrometer, an infrared camera, thermocouples, a spectrometer and recorded with a 4k video camera. The measurement results are in good agreement with the numerical simulations for the S-Band antenna, camera and titanium rods but differ for the magnetorquers, CFRP sandwich structure and PCBs. In particular, PCBs are candidates for hard-to-demise components in satellites that require an improved model for numerical simulations. The sensor validation test is showing the expected results in sensor performance, according to preliminary analysis.
Demisability Investigation With the CubeSat SOURCE: Plasma Wind Tunnel Experiment Results
Utah State University, Logan, UT
The increasing utilization of small satellites in Low Earth Orbit (LEO) facilitates ground-breaking opportunities including telecommunication, Earth observation, gravimetry, Space Situation Awareness (SSA) and atmospheric science. However, it also creates a challenge for space debris mitigation and space traffic management. Current numerical tools predicting satellite demisability during uncontrolled atmospheric entry lack accurate models, hindering the estimation of component survivability which is needed for a sustainable growth in orbital commercialization. The University of Stuttgart’s Institute of Space Systems, together with the small satellite student society KSat e.V., addresses this issue with an interdisciplinary satellite re-entry analysis. This includes in-situ measurements in the early phase of re-entry with the Stuttgart Operated University CubeSat of Evaluation and Education (SOURCE), a 3+ Unit CubeSat scheduled for launch in 2025. The payload contains sensors for pressure, temperature, heat flux and atomic oxygen measurements during the early phase of re-entry at altitudes above 130 km. Iridium communication ensures a ground station-independent data downlink. Furthermore, numerical simulations with SCARAB (Hyperschall Technologie Göttingen, HTG) and PICLas (University of Stuttgart, IRS) including analysis for free molecular and continuous flow regimes identify critical components and points of interest in the trajectory. The demisability analysis is completed with plasma wind tunnel experiments. The plasma wind tunnel used for the tests at the University of Stuttgart is PWK1, which utilizes the self-field magnetoplasmadynamic plasma generator RD5 to create high-enthalpy air flows relevant for re-entry emulation. Three distinct trajectory points at different altitudes have been identified as test environments for the component tests, where relevant demise processes take place according to the numerical simulation results. An 80 mm diameter heat flux-pitot pressure probe was used to characterize the high-enthalpy flow, which emulates stagnation point conditions of the discrete trajectory points with focus on mass specific enthalpy and total pressure. The following components were selected as potential hard-to-demise components of SOURCE: The S-Band antenna, magnetorquers, printed circuit boards, a Carbon Fibre Reinforced Polymer (CFRP) sandwich structure, titanium rods, a camera, and batteries. Moreover, an experiment was conducted with a mock-up of SOURCE including functioning sensor arrays in a very low enthalpy environment to verify and investigate the reaction time of the in-situ measurements. All experiments are monitored with a linear pyrometer, an infrared camera, thermocouples, a spectrometer and recorded with a 4k video camera. The measurement results are in good agreement with the numerical simulations for the S-Band antenna, camera and titanium rods but differ for the magnetorquers, CFRP sandwich structure and PCBs. In particular, PCBs are candidates for hard-to-demise components in satellites that require an improved model for numerical simulations. The sensor validation test is showing the expected results in sensor performance, according to preliminary analysis.
