Speaker
Description
European Space Thermal Engineering Workshop 2024
by Adeeb Nazeeruddin, Thermal System Engineer at Beyond Gravity Switzerland
Thermal design and analysis of FLEX spacecraft
The FLEX spacecraft is part of The Earth Explorer - Fluorescence Explorer (FLEX) ESA mission, which will map vegetation fluorescence to quantify photosynthetic activity. Its objectives are to:
- To assess the quality of fluorescence-derived photosynthesis data against classical optically based methods (i.e. from fraction of absorbed photosynthetically active radiation times Light Use Efficiency).
- To identify and characterize the effects of different types of stress on fluorescence and photosynthesis (especially drought and freezing air temperatures).
- To indicate potential applications of the novel fluorescence observations.
Information from FLEX will improve our understanding of the way carbon moves between plants and the atmosphere and how photosynthesis affects the carbon and water cycles.
Beyond Gravity Switzerland, acting as platform design authority for TASF and TASUK, designed, analyzed and manufactured FLEX platform structure. Among the set of analyses done, thermal analyses focused on the thermal loads encountered by its various orbital profiles and assessed the temperatures that the different units would be facing. TASF provided as inputs various mission environments to consider and various reduced thermal models of the units to be taken into account for thermal calculations.
The present work aims to address the design and architecture of the thermal control system and modelling and analysis approach taken by Beyond Gravity Switzerland in order to model the platform structure in reasonably accurate way.
Two thermal models were built using the software Esatan 2018, each representing a configuration of the Spacecraft.
The first model, which is a deployed configuration model, was built in order to assess orbital phase scenarios, with different orbits, attitudes and dissipation profiles, environmental and boundary conditions.
The second model, which is a stowed configuration model, was built in order to assess LEOP scenarios. This model was used in order to assess the impact of aerothermal fluxes, thruster plume loads impact and environmental loads.
Panels are made of Aluminum sandwich structure. Various units and antennas were modelled to represent as accurately as possible the Computer Aided Design model created by the design team and the suppliers’ datasheets. Following various orbital assessments, radiators and MLI and heating lines were sized and defined. One of the main challenges was to keep the interface with the instrument to its own limited thermal range to avoid any significant thermo-elastic distortion and heat exchange between the platform and the instrument.
The focus of the activities was on the right sizing of the MLI, radiators and heating lines in order that the temperatures reached by the various units and instrument interface remain within control. Predicted temperatures include a certain uncertainty calculated through sensitivity analyses following ECSS standards.
As part of the modelling is based on engineering assumptions that were purposefully conservative, it avoids risks but leaves room for improvement and validation with a thermal balance test. The thermal model built is expected to be correlated in 2025.
