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European Space Thermal Engineering Workshop 2024
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Europe/Amsterdam
Einstein and Newton (ESA/ESTEC)
Einstein and Newton
ESA/ESTEC
Keplerlaan 1
2201 AZ Noordwijk
The Netherlands
Description
🚀Please note that the ESA Open Days 2024 will take place on 5-6 October at ESTEC, just prior to the European Space Thermal Engineering Workshop. This is a great opportunity to explore ESA’s activities and meet our experts before the workshop begins on 8 October 2024.
For more information check the following link: ESA Open Days
INTRODUCTION
The European Space Thermal Engineering Workshop, organised by the ESA Thermal Division, will be held on:
Tuesday 8 to Thursday 10 October 2024
at ESA/ESTEC, Noordwijk, the Netherlands.
The event is held live at ESTEC only, not hybrid or on-line!
Aim and scope
The aim of the workshop is:
- to provide a forum for the exchange of views, experiences, best practices and lessons learned from thermal engineers involved in space missions
- to promote and facilitate contact between thermal engineers and thermal technologies and tool developers
- to present recent developments on all aspects related to the thermal engineering domain and to solicit feedback
- to present new approaches and methodologies (e.g. for thermal design, analysis and verification)
Topics covered include in particular
- thermal design (for platforms, instruments etc.)
- thermal analysis and software tools
- thermal testing
- thermal control technologies
- heat transport technology
- thermal technologies and methodologies related to small satellites and CubeSats
- mapping of thermal results to mechanical models and guidelines for thermo-elastic (for thermal part)
- Thermal for surface missions
Organisation
The workshop will consist of presentations only. The working language will be English.
SMILE in LSS model
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Registration Einstein and Newton
Einstein and Newton
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Welcome Newton
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Convener: Dr Harrie Rooijackers (ATG-Europe)- 1
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General introductionSpeaker: Olivier Pin
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ESA Missions and Thermal Technology Development UpdateSpeaker: Stephane Lapensee (ESA)
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11:00
Coffee Break Einstein and Newton
Einstein and Newton
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Small Satellites and CubeSats Einstein
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Convener: Malgorzata Solyga-
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Thermal design, test and performance characterization of a smallsat for an Earth Observation constellation
Earth observation spacecrafts have seen a great interest and development in the past years and, still nowadays, it is one of the most prominent space markets thanks also to the miniaturization of the satellite platforms that allows to rapidly build constellations. In this presentation, the full development of a smallsats for Earth Observation is shown with a major focus on the thermal aspects. The case study is the HEO (Hawk for Earth Observation) spacecraft built for the first Argotec Earth Observation constellation, which will operate within the IRIDE constellation. IRIDE is an Earth observation satellite constellation developed on the initiative of the Italian government, with the support of the resources of the Italian National Recovery and Resilience Plan (PNRR). The work shown will start from the description of the first preliminary ESATAN thermal model (TMM and GMM) to the detailed ones, with insights on the numerical statistics and considerations on the differences in computational effort and modelling strategies. What has been noted is that an increase in TMM and GMM details does not always gives a justifiable results resolution increase wrt the increase in computational time and heaviness of the model. Considerations and results on modelling approaches to have the best trade-off between details and results worthiness are given. Then a description on how the TVC has been prepared and conducted to better replicate the worst cases orbital thermal maps of the spacecraft are shown, explaining how we were able to overcome test setup limitations. The satellite thermal map is mainly driven by the sun-pointing attitude of the satellite during most of its lifetime; hence the principal thermal gradient goes from spacecraft’s sun-side to anti-sun side. To replicate this behaviour without UV lamps or simulation chambers, a differential temperature control between thermal plate and shroud on the TVC has been used to heat up the sun-side and then, with the shroud, simulate the heatsink of the space environment. Limitations of this test setup relies in the impossibility to verify, for example, the solar absorptivity of the external surfaces. Eventually, the thermal model correlation results are shown with statistics evaluation of the results, considering checks also for the thermal inertia of the system, a major aspect for a satellite that works constantly in a transient thermal scenario. The last topic will be the description of the thermal control strategy foreseen to gain the focus on the optical payload. The capability to well observe the Earth surface strictly depends on the performance of this element and its capability to maintain optical focus during spacecraft’s nominal operations avoiding the use of a mechanical focuser. The use of the latter represents a single point of failure for the mission, hence the use of a proper TCS to keep the optical focus permits to relies on a more robust control system. Usually, optical payloads are designed to correctly perform in a narrow temperature range around 20°C, hence having the ability to maintain the payload within these temperature limits allows to guarantee the correct mechanical alignment of all the element in the optical path and then gain the focus. Finally, considerations on the effects of the thermal environment (solar flux, albedo and IR) are done and a final thermal control strategy for the optical payload focusing is described. A final short appendix will be added to show preliminary thermo-elastic results with the objective to study their effects on the relative positions between start trackers and optical payload during the orbit. These thermo-elastic displacement errors will be implemented on the ADCS to gain the best possible attitude control and then reduce also the pointing error on the Earth ground during the acquisition. The ESATAN output satellite thermal map is given as input on a FEM software to run static structural analysis that have temperature as load.
Speaker: Francesco Latella (ARGOTEC S.R.L.) -
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FENNEC: A Deployable Radiator for The Next Generation of High-Power SmallSats
FENNEC (FoldablE Newspace NextgEneration radiator for CubeSats) is a deployable radiator designed to meet the increasing demand for advanced thermal management systems in CubeSats and other SmallSats.
In the past, despite the typically higher power density of SmallSats compared to larger spacecraft, the external structural surfaces of such platforms have usually been sufficient for thermal management. Nowadays, as the role of such platforms is transforming from mere test beds for in-orbit demonstration of new technologies towards regular commercial use, the demand for longer payload duty cycles and electrical power is growing steadily, with main applications in inter-satellite and space-to-ground communications and on-board data processing, as well as in electric propulsion. This calls for more advanced thermal management solutions, capable of dissipating large amounts of heat.
The FENNEC project aims to create a reliable, easy-to-use, modular COTS system that enhances the radiator surface area on a SmallSat with deployable radiator panels. The current baseline design is intended to replace a 3U panel on a 3U or 6U CubeSat to reject up to 50 Watts with two deployable radiator wings. Other sizes are planned once the design is fully verified. After deployment, FENNEC is a fully passive system that requires no control or electrical power to perform its task.
FENNEC is being developed by a consortium of German NewSpace companies led by Dcubed and is co-funded by the European Space Agency under the ESA ARTES C&G program. The project is currently preparing to undergo Preliminary Design Review by the end of 2024.
Figure 1: The FENNEC deployable radiator (artistic rendering).Speakers: Mr Benedikt Bauer (Dcubed GmbH), Mr Chirag Singh Mukherjee (German Orbital Systems) -
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Thermal Analysis of the CHESS Pathfinder 1 CubeSat Mission
The CHESS (Constellation of High-Performance Exospheric Science Satellites) mission aims to enhance our understanding of the Earth’s upper atmosphere through direct measurements (species number density, altitude profiles, total electron content, ion population, and dynamics) using two twin 3U CubeSats: Pathfinder 1 & 2. The mission is managed by the student association EPFL Spacecraft Team, which is also responsible for building the entire satellite platform. The scientific payloads are provided by the University of Bern, developing the CubeSatTOF mass spectrometer, and ETH Zurich, developing the GNSS receiver. Pathfinder 1 is scheduled for launch into a circular Sun-synchronous orbit at an altitude of 550 km by the end of 2027, with an operational lifespan of two years, while Pathfinder 2 will follow two years later in an elliptical orbit.
Such satellites in low Earth orbit face challenging thermal conditions due to fluctuating irradiation from alternating light and eclipse phases, combined with varying internal heat dissipation. For the CHESS CubeSat, where most subsystems are designed in-house, tailored thermal management is therefore essential. A robust thermal control system must be designed and simulated to keep all components within safe temperature limits, ensuring reliable satellite operation throughout its mission.
Hence, this study embarks on a comprehensive thermal analysis of the CHESS Pathfinder 1 satellite during orbiting operations using Systema-Thermica. Structured in three parts, it first details the model's geometry, materials, internal heat dissipations, and thermal couplings of the satellites instruments and platform subsystems. Next, it identifies worst-case scenarios and presents the corresponding results for the hot and cold cases. Finally, design modifications and mitigation strategies to ensure all components operate within safe temperature ranges under the various system modes are suggested. These findings not only enhance the CHESS mission's success but also offer valuable insights that can be applied to the thermal design for future CubeSat missions.
Speakers: Lina Kuhlmann (EPFL Spacecraft Team), Valentin Moret (EPFL Spacecraft Team)
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Thermal Analysis Newton
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Convener: Arthur Dunlop (ESA (ESTEC))-
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ANTENNA THERMAL ANALYSIS OF AEROBRAKING PHASE – A TASI APPROACH
Through space exploration, we gain a new perspective to study Earth and the solar system. The number of missions based on the study of the surface and interior of the planets are increasing every year, and the aerobraking phenomena are inevitable when we are very close to a planet atmosphere. On the other hand, several missions to other planets have already exploited aerobraking, in order to save the amount of propellant carried and therefore optimize vehicle design mass.
Since the Antenna is located on the external part of the spacecraft, it is greatly affected by the heat generated during the aerobraking maneuvers and dedicated analyses are needed in order to predict the antenna thermal performance throughout the entire time.
From an industry point of view, phase A and B analyses must be performed rapidly and reliably taking into account the tight project schedule. The purpose is to successfully design all the antenna items to withstand the aerodynamic forces and heating associated with the entry velocities, as well as to develop dedicated technologies to optimize the overall antenna performances.
The most important analysis is to predict the nominal temperatures for the next orbit drag pass, but also to identify those antenna orientations or spacecraft attitudes that define the technological limits of the antenna. This allows the spacecraft GNC (guidance & navigation control) team to effectively plan the correct maneuvers and drag pass without an excessive heating of the antenna.
The proposed approach is to use a commercial software, without the need to develop dedicated subroutines or interleave multiple packages. The data presented will show how to have a comprehensive Antenna temperature prediction, based on the spacecraft position, as well as the density and velocity at different trajectory points. #Speaker: DIANA SCIULLI (THALES ALENIA SPACE ITALIA) -
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THERMAL MODELLING OF LARGE DEPLOYABLE REFLECTOR MESH SURFACE
Thales Alenia Space Italy is developing a Large Deployable Reflector (LDR) based on modular and scalable cells.
The reflective surface of LDR is a warp knitted metallic fabric, made of thin wires, able to assure a high electric conductivity.
The thermal characterization of the mesh presents challenges due to the inapplicability of standard methodologies. To address this, an equivalent 2D thermal mathematical model of the mesh was developed, enabling accurate predictions and yielding time and cost savings
Additionally, a detailed 3D thermal mathematical model of a representative unit cell of the mesh was built, using a dedicated algorithm based on a geometrical representation-
The 3D model was used to estimate the thermo-optical properties to apply to the 2D model, including an equivalent transmissivity and a corrective factor sun angle-related absorptivity / emissivity, accounting for contributions from infrared and ultraviolet wavelengths.
Furthermore, sensitivity analyses were performed to assess the impact of wire diameter and the number of nodal networks in the 3D model.Speaker: GIOVANNI DI LELLA (Thales Alenia Space Italia) -
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Thermal modelling of an optical instrument using ANSYS FEA
The Central Institute of Engineering, Electronics and Analytics, Engineering and Technology (ZEA-1) of the Forschungszentrum Jülich GmbH (FZJ) develops and manufactures scientific-technical devices, systems and processes, that are not available on the market, with and for our scientific partners. The SHIPAS measuring device, an optical instrument for observing the mesosphere, is currently developed at the institute as a first project that has to fulfil the requirements for space missions.
In this presentation we depict our approach for thermal modelling using the finite element software ANSYS as simulation tool so the model might also be used in subsequent thermo-structural and STOP-analyses. Details of the finite element model and of the handling of the heat and radiation boundary conditions are introduced with a special emphasises to the consideration of orbit dependent data. We present how the model is used to derive a representative lumped model and we will discuss advantages and disadvantages of the methods used. Moreover, we give ideas in which way our approach might be beneficially altered for future projects.
Speaker: Marian Partzsch (Forschungszentrum Jülich GmbH)
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13:00
Lunch ESTEC Restaurant
ESTEC Restaurant
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Heat Transport Einstein
Einstein
Convener: Paula Prado Montes-
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Recent advances in EHD-based pumped loops and thermal switches
Based on the electrohydrodynamic (EHD) technology mastered by APR Technologies, a Swedish SME, the core of APR's space products is a small-sized patented liquid EHD pump. This pump enables very deterministic and fast regulation of fluid flow, thereby controlling thermal conductance between thermal interfaces in active thermal control systems. Its main advantage is its operation across a wide temperature and thermal flux range with power consumption below 2 W, in OFF mode, power consumption is 0 W. Since the pump has no moving parts, it experiences no mechanical wear or vibrations.
During 2023 and 2024, APR's space product portfolio of thermal switches and pumped loops has grown, with three branches for each product family.
EHD pumped loops are built similarly to mechanically pumped loops, with tubing connecting the heat exchangers (cold plates), pump, and volume compensation. The mechanical pump is replaced with an EHD pump, which has the advantage of no moving parts. The pumped loop family consists of a cryogenic low-OFF single-phase loop at TRL 4 and a single-phase loop at TRL 5 (3 kg) targeting telecom with a 100 W load. Additionally, an EHD pumped two-phase loop targeting high-power applications has been demonstrated in a national activity and is currently at TRL 4.
EHD pumped thermal switches are compact devices where the thermal conductance between two interfaces can be modulated by controlling the fluid pumping between the interfaces within the device volume. In zero gravity, the stationary fluid has a high thermal resistance, leading to low thermal conductance between the interfaces in OFF mode. Conversely, in ON mode a large amount of heat can be transported by the pumped liquid. The thermal switch developed within the Neosat program targets 150 W loads, has a mass of 1400 g, and a turndown ratio of about 25. Two smaller thermal switches, developed to TRL 5 in a GSTP activity for lunar surface exploration batteries (150 g) and smallsats (260 g), have anticipated turndown ratios of over 50 and 11, respectively.
Speaker: Mr Robert Thorslund (APR Technologies) -
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Fluid selection in a two-phase mechanically pumped loop testbench for aerospace applications
In modern times, the rapid growth in the volume of data and the needs for global connectivity are major technological challenges. At this point, satellite technology attempts to respond to various demands, ranging from guaranteeing internet access in remote regions to national security missions. The growing demand for satellite devices and the expectation regarding the tasks assigned to this technological infrastructure are associated with greater processing capacities, increase of number of hot sources, higher electrical power consumption and therefore new challenges in the design of thermal control systems. In this regard, the limitations of passive systems such as heat pipes (HP) and loop heat pipes (LHP) have led to the emergence of two-phase mechanically pumped loop as a solution to variable heat capture and rejection conditions. This cooling technologies based on flow boiling have shown their thermal management capacity in space applications in recent years, where ammonia (NH3) and carbon dioxide (CO2) have been substances successfully used in thermal control systems with a technology readiness level TRL 9 (system proven in operational environment). However, there are knowledge gaps about the parameters influencing flow boiling dynamics in evaporation and condensation components. The objective of this work is to present a fluid selection methodology under environmental and operational safety considerations, while figures of merit (FoM) proposed by the literature are used to estimate thermohydraulic advantages. Finally, the selection of two fluids suitable for experimentation in a testbench for aerospace applications is presented. The overall purpose of the criteria applied to this selection will be to promote the understanding of flow dynamics in a two-phase mechanically pumped loop (2pMPL), allowing future exploration of improvements in heat transport and adaptation to changing environmental conditions for satellite applications.
Speaker: Mauricio Pedroza-Torres (Research engineer / ULiège) -
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On-ground testability of complex thermal bus for accurate temperature regulation with Constant Conductance Heat Pipes (CCHP) and Variable Conductance Heat Pipe (VCHP)
The accurate temperature regulation of system or sub-system is a key enabler for space scientific missions, especially when observation instruments are considered. The thermal management of optical technologies are critical and may require a fine temperature control with accurate stability, and a homogeneous temperature field. Thermal buses composed by CCHPs and VCHPs propose high reliability and performances in micro-gravity, but on-ground testability induces the management of the gravity aspects, amplified with possible out-of-plane geometries and spacecraft orientations limitations. The gravity effects of planetary missions or induced by spacecraft movement can also be considered.
The proposed paper exposes the gravity impacts observed during the testing of a spacecraft designed for observation mission, which relies on the cold operating temperature regulation (around -30°C) in a complex geometrical configuration (not planar). The on-ground tests sequence shall be secured using additional heater to mitigate the gravity induced temperature instabilities on CCHPs. Also, a specific focus is done on Variable Conductance Heat Pipes (VCHP) to expose how their behavior is affected by gravity. A specific thermal test campaign has been realized to better understand these phenomena.Speakers: Dr Mikael Mohaupt (Lead Design Engineer at EHP), Yann Cervantes -
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Development of Multievaporator Heat Loops
Single evaporator heat loops (HL: LHP, CPL, etc.) are well-studied two-phase heat transfer devices, both theoretically and through many applications in spacecraft thermal management. Classical HL are well suited for operation with concentrated heat sources. However, collection of heat from a wide flat area by HL evaporator comes at a cost of using additional interfaces (saddles, embedded heat pipes, vapor chamber etc.) or using multiple LHPs. These solutions bring unwanted thermal resistance at interfaces or complicate assembly and integration.
Another way to solve the task is through the use of multievaporator LHP, which is currently going through engineering model development stage. Multievaporator, comprising a grid of interconnected capillary pumps and compensation chambers, is at the core of technology that may adapt classical LHP to unconcentrated heat sources, often present in spacecraft modules. With 250x250 mm heat collection interface, overall LHP conductance with 6 m long transport lines can reach 100W/K value.
Multievaporator has demonstrated operation with different working fluids, such as ammonia, butane, R1233zd(E) and R134a, with different length of transport lines (up to 16m with ammonia), as well as various heat rejection modes and their combinations: radiation as in space environment, but also forced and natural convection, helpful for characterization. Throughout the characterization tests, the test setup was developed from measurement of steady state heat transfer capability to going through shock transient regimes, including variation of loop hydraulic resistance, heat sink temperature and heat transfer coefficient.
Overall, multievaporator LHP is a versatile device. Its modularity make it possible to adapt for different use scenarios regarding choice of working fluids, length of transport lines and heat source power and dimensions.Speaker: Luka Ivanovskis (Allatherm SIA)
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Thermal Analysis Newton
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Convener: Matthew Vaughan (ESA)-
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Thermal Control System: a design data model to facilitate digital continuity
The use case presented in this presentation is the Model Based Thermal Control Design (MBTCD). This activity is initiated in parallel to the DOTEP (Digitalization Of the space Thermal Engineering Process). DOTEP focuses on developing a prototype of a data model for thermal engineering processes from conceptual, to logical and physical data. However, MBTCD is focusing on the first layer (conceptual layer). The final output of this activity can be integrated with SSO and DOTEP to ensure the digital continuity. Moreover, it can create a framework for interface management between different space engineering domains. This will facilitate for instance CDF studies where domain engineers need to work concurrently with each other. The main objectives of MBTCS are then:
• Manual work reduction by digital continuity in data from design phase to analysis phase.
• Design knowledge reuse.
• Review processes optimization.
• Design performance estimation improvement.
This has the capability to enhance industry databases, thereby fostering digital continuity.Speakers: Alexandre Darrau (ESA), Mrs Elaheh Maleki (ESA) -
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Digitalization of Thermal Engineering Processes
The digital transformation of engineering processes for space system development is crucial for technological advancement and efficiency in the European Space sector. Our presentation explores Starion, DEKonsult, and OHB's approach to implementing innovative technologies as piloted by the European Space Agency with their Space System Ontology, with a focus on thermal engineering.
Initially, we identified the core processes within the thermal engineering domain across all lifecycle phases, targeting areas most likely to benefit from digitalization. This strategic focus ensures that digitalization efforts address significant pain points and lead to substantial workflow improvements. We developed a Conceptual Data Model (CDM) using NORMA Pro, iterating with stakeholders to capture essential thermal engineering process concepts for both design and analysis, fitting within the broader Space System Ontology developments.
We then translated the CDM into a Logical Data Model (LDM) using SysML version 2 (SysML2), representing complex relationships within thermal engineering in a logical structure. This marks the first use of SysML2 in this context, bridging abstract concepts and practical implementations and enabling specification of example LDM populations for validation use cases.
Finally, we transformed the CDM and LDM into a tangible pilot demonstration by creating a C# class library and implementing a graph database store using dGraph technology. This combination forms the Physical Data Model (PDM), packaged as a plugin module for Starion’s prototype Model Based Engineering Hub. During the activity we also developed tailored UIs for the two selected use cases, as well as a small plugin for ESATAN-TMS to help with automated transfer of relevant information.
Speaker: Mr Hans Peter de Koning (DEKonsult) -
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Development of a CPU- and GPU-based Ray Tracer for Space Applications
This work presents the development of a software tool for view factor (VF) and radiative exchange factor (REF) calculations on ESATAN-TMS geometry files using Monte Carlo ray tracing (MCRT). VFs and REFs describe the radiation heat transfer between two surfaces. The software can use both the central processor unit (CPU) and the graphics processing unit (GPU) to perform the computations. It is verified against ESATAN-TMS, which shows that the same accuracy levels can be achieved. Since a large number of rays need to be traced to achieve accurate results, calculating VFs and REFs through MCRT is computationally expensive. Several methods to reduce the computation time are presented, together with the capabilities and limitations of the software.
The CPU implementation uses vectorized MATLAB code to partially parallelize the most demanding calculations on a single CPU core. Furthermore, bounding volumes are used to accelerate the ray traversal. Since the rays do not affect each other, the tracing process can easily be parallelized. This is accomplished by using multiple CPU cores to trace multiple rays simultaneously. While these methods decrease the computation time on the CPU by a factor of up to 200, the CPU implementation is still around 100 times slower than ESATAN-TMS.
To further reduce computation times, the parallel architecture of GPUs is utilized. The GPU code is written using the NVIDIA OptiX API to access dedicated ray tracing cores on GPUs. These cores are specifically designed to handle ray tracing tasks such as ray-triangle intersection testing. By distributing the workload across thousands of parallel threads, up to 400 times faster calculation times than ESATAN-TMS are achieved.
Speaker: David Thermann (FH Aachen University of Applied Sciences) -
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Creation of two thermal models of the 4N / 10kNs-class propulsion system using step-TAS and ESA’s TD TAS converter
A thermal model of Dawn Aerospace’s 4N / 10kNs-class propulsion system was created in Systema Thermica. The model includes the main components of the system and represents conductive and radiative couplings. Additionally, a thermal model in thermal desktop was requested.
The Thermal Desktop Model was derived from the original Thermica model by utilizing ESA’s TD TASverter. To accomplish this, the thermica model was exported into the generic STEP-TAS file format (Thermal Applications for Space) using the native export functionality of the software. Afterwards, the STEP-TAS model was converted into a thermal desktop model using an ESA created software code. Final adjustments were made manually to apply material properties and interfaces.
The experiences, challenges and lessons learned derived during this process will be presented. A special focus will be given to the tasks which were performed manually
Speakers: Mr Alexander Walker (Lunar Outpost US), Tobias Flecht (LunarOutpost EU)
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16:00
Coffee Break Einstein and Newton
Einstein and Newton
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Thermal Control Newton
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Convener: Dr Philipp Hager (ESA)-
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Phase Change Material Heat Capacitor: performance reached for an hypersonic glider and industrialisation
The use of a Phase Change Material Heat accumulator is becoming a first choice for thermal engineers. After a successful flight on-board Ariane 6 maiden flight, implementations in a future low-cost private European launcher and an hypersonic glider, the use of this passive heat absorber has become the final choice of trade-off with other thermal systems. In particular, the performance, reached in a DLR facility, of an hybrid heat storage device will be presented. Industrialisation is also a must for further usage in applications such as constellations and generic LEO platforms. A family of "off the shelves" devices has been defined. But, the choice of additive manufacturing also allows easy adaptation of the design, especially the thermal and mechanical interfaces.
Speaker: JP Collette (Walopt) -
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Phase Change Material in Space Electronic Systems for ADHA and Space VPX standards: simulations and TVAC testing
Advanced Data Handling Architecture (ADHA) standard [1] (under development by ESA with industrial partners) is a standard for the on-board computers and data handling systems to assure interoperability and cost efficiency. It utilizes standardized plug-in electronic modules interconnected in larger enclosures called electronic boxes. A similar philosophy was adopted to an older standard called SpaceVPX (Vita 78). However, with rising power demands for on-board spacecraft processing of data, comes increased thermal dissipation which limits the possible performance of the ADHA and SpaceVPX based modules. Simulations and experiments performed by KP Labs showed the importance of proper thermal design of such modules. In some scenarios, temperatures of electronics can rise above 75°C, which is undesirable for a reliability of electronic components [2]. Additionally, the periodic operation of the module’s electronics creates thermal cycles that significantly reduce the component’s lifetime [3]. To address these issues, the authors proposed the utilization of a novel 3D printed mechanical enclosure with embedded Phase Change Material (PCM), applied on a module level. The goal of this solution is to store energy in the form of latent heat during high power dissipation phases and release it during non-operational phases. This in turn would reduce temperature fluctuations and prevent overheating of electronics, thus enhancing their reliability.
The core novelty of the authors’ approach lies in the design and development of a PCM based Data Processing Unit (DPU) module to the ADHA and SpaceVPX standards, marking the first known integration of a PCM system with these standards. This extends the authors' previous work, which tested only the module enclosure with embedded PCM. In current work, for the first time, electronics are used with PCM enclosure in the form of the Engineering Model of Lion DPU developed by KP Labs for SpaceVPX standard.
The authors conducted numerical simulations of the new DPU with a PCM-based enclosure. The detailed numerical FEA model was used to analyze the processes within the DPU module in detail. It allowed for an in-depth study of the entire concept, including the influence of gravity vector on the heat transfer. However, to speed up the future development, the complex FEA model was simplified to a nodal model in ESATAN TMS. Such simplification will also allow for easier exchange of thermal models with Large System Integrators (LSI). In ESATAN, the DPU’s geometry was represented as a network of 1D nodes with representative heat capacitances and power dissipations, connected by one-dimensional conductive links. The PCM was modeled as a node with temperature-dependent heat capacity. This approach reduced computational power and shortened calculation times, a significant benefit for the engineering community designing space electronics.
A physical DPU prototype was manufactured and tested inside a Thermal Vacuum Chamber (TVAC). Paraffin n-eicosane, with a melting temperature of 37°C and a latent heat of 247 kJ/g [3], was used as the PCM. To address the challenge of low thermal conductivity of the selected paraffin, the aluminum PCM container was created with additive manufacturing technology. This approach allowed for the creation of a hollow mechanical enclosure with 3D printed fins, while keeping the mechanical requirements of SpaceVPX standard.
The experimental procedure consisted of a Thermal Balance Test (TBT) and a Thermal Cycling Test (TCT). During the TBT, phase change occurred, slowing the temperature rise of the Lion’s electronics, which experimentally confirmed the PCM's positive impact on the DPU's thermal design. Following these real-life results, the simulations (both the detailed and simplified) were validated and compared. During the TCT, the PCM stabilized the temperature variation of the electronic components. The obtained results and correlation between numerical simulations and TVAC tests will be presented in detail during the author’s presentation.
The simulations and subsequent TVAC tests of Lion DPU EM proved the concept of the PCM-based module for SpaceVPX in real operational scenarios. By utilizing a phase change, temperature spans can be significantly reduced with relatively low additional mass added to the DPU. This solution offers benefits in terms of extending the operational lifetime of the electronic components. The authors are currently working on the possible extension of this approach to the ADHA standard, to meet future demand of the growing on-board data handling solutions market.
References:
[1] Advanced data handling architecture - adha, accessed: 2024-03-24. URL https://technology.esa.int/page/advanced-data-handling-architecture-adha
[2] S.M. Sohel Murshed, C.A. Nieto de Castro, “A critical review of traditional and emerging techniques and fluids for electronics cooling”, 2017
[3] Sharon, Gil & Caswell, Greg. . Temperature cycling and fatigue in electronics. Advancing Microelectronics. 42. 18-24. (2015)
[4] Serale et al. Potentialities of a Low Temperature Solar Heating System Based on Slurry Phase Change Materials (PCS). Energy Procedia. 10.1016/j.egypro.2014.12.397. (2014).Speakers: Artur Jurkowski, Radosław Paluch -
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Development of efficient concepts for mounting of thermal MLI blankets
Passive thermal control of a satellite is typically performed using multilayer insulation (MLI) blankets. The current state-of-the-art method for MLI fixation makes use of stand-offs, which are glued to the spacecraft structure, and clip-washers, which fix the blankets on these stand-offs. This method is highly reliable and has a wide heritage, however it is time-consuming for several reasons: For a typical satellite more than 1000 stand-offs with variable geometries are involved. It is common that positioning clashes with adjacent hardware such as harness occur during installation, which requires lengthy clarification between AIT teams. Since the state-of-the-art stand-offs are rigid items, the stand-off holes can only be punched in the blankets after an on-site integration fit-check of the blankets is performed. All these circumstances lead to a long throughput time of blanket installation.
The goal of the ESA GSTP project “MLI Efficient Mounting” is to overcome these drawbacks by developing alternative MLI mounting systems, which considerably reduce the time effort and overall cost for MLI integration. Apart from the commercial aspects, the characteristic technical requirements were verified, such as electrical grounding, thermal performance, cleanliness, outgassing, removability, overlapping and interfaces, environmental conditions (thermal conditions, vibrations).
Based on the given specifications that both local and global mounting techniques shall be developed, different solutions were investigated over the course of the project, and a trade-off performed, ranking the options regarding their viability. In the end, two different types of local fixation elements and one global solution were selected. The local techniques focused on an improvement of the flexibility and on standardization. An alternative stand-off type has been investigated, which consists of a standardized base and a standardized shaft in the form of a ball rod, which has rotational flexibility inside the base and can be cut to length as needed. The second local solution focused on a novel type of self-adhering, reclosable fastener. The global solution makes use of standardized, lightweight secondary structure frames with pre-mounted MLI blankets. This concept also facilitates the standardization of the MLI blanket design and attachment to the structure.
A qualification campaign has been performed to aim for TRL 5. Several breadboards were manufactured representing typical spacecraft geometries. The breadboards were subjected to thermal-performance, -cycling and mechanical vibration testing. Additional sample tests, confirming temperature capability and outgassing, supported the proof of concepts. The integration feasibility of the novel concepts was demonstrated on a 2m x 2m mock-up, which represented a full-scale satellite panel including typical items, e.g. brackets, harness, radiators and pipes.
The selected attachment designs and finally qualified concepts will be subject of this talk.Speaker: Klaus Reitterer (Beyond Gravity Austria GmbH)
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Thermal Testing Einstein
Einstein
Convener: Victor Cleren (ESA)-
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THERMAL TESTING & CORRELATION IN THE FREQUENCY DOMAIN
Nowadays, testing remains a key milestone in the verification of the thermal control subsystem of any space project. TVAC tests have two main goals: the verification of the correct operation and survival of the system under thermal environmental conditions representative of the orbital scenario, and the reduction of the thermal model uncertainties by means of thermal balance tests and later correlation.
Correlation based on thermal balance tests requires reaching thermal equilibrium under a series of boundary and operational conditions. As a result, tests become very long and expensive, and one risks overloading locally some regions of the system.
An alternative to traditional thermal balance tests to generate data for correlations would then become an attractive solution. Thermal characterization by means of transient tests based on oscillatory heatloads and the use of phase shift between the different locations of interest is a common practice outside of the space sector. This methodology allows the thermal engineer to perform thermal correlations of models based on periodic responses with low amplitude, and therefore avoiding over stressing, without the need to reach thermal balance, shortening the total test duration. In addition, by not relying on the amplitude of the response these tests are insensitive or have greatly reduced sensitivity to heat leakages allowing for e.g. out of vacuum testing. Furthermore, by running multiple oscillatory profiles at the same time at different frequencies and by subsequent decomposition of the response (i.e. frequency decomposition) multiple characterization tests may be performed at once.
While this approach will definitely not replace traditional TVAC tests, for some applications it may offer distinct advantages over more traditional approaches and can reduce the time needed in TVAC. This presentation displays the first numerical and experimental steps performed to consolidate a correlation methodology for space systems based on phase shift responses under oscillatory headloads.
Speaker: Mr Alexander van Oostrum (ATG Engineering) -
22
Debugging a STM test for the SXI instrument on SMILE
The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a collaborative effort between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). The primary objective is to better understand the interaction between the solar wind and the Earth’s Magnetosphere. The primary payload is the Soft-Xray Imager (SXI) instrument, which is an x-ray telescope build by the University of Leicester, UK and funded primarily by the UKSA. The telescope will image the motion of x-rays with the Earth’s magnetic boundaries including the bow shock, magnetopause, and cusps.
The telescope features two CCD detectors which are passively cooled to 155K by three staged radiators: a telescope radiator at 180K, a baffle radiator at 170K and, a detector radiator at 145K.
During the instrument STM in 2021, significant temperature discrepancies up to 40K were seen between the test data and the thermal model predictions in the balance phases. Due to limited time before the next level STM test, a systematic root cause analysis was performed to ‘debug’ the main issues. This was carried out via ad-hoc test phases, thermal sensitivity analysis and test article inspection. Estimates of each root cause were quantified using heat balances and equivalent parasitic heat loads. Finally, the main root causes producing > 10% of the total parasitic were corrected with design solutions and modifications to the test setup.
The main root causes were identified as test harness, detector flexi radiation, decreased MLI efficiencies and facility / test-setup. These were subsequently corrected at the PLM level STM and the SXI PFM and detector temperatures of 145K were achieved. The presentation will focus on the lessons learned from the root-cause analysis and is particularly relevant for thermal designs with 'very cold' zones that might not get the same level of attention as cryogenic thermal designs.
Speaker: Matthew Vaughan (ESA) -
23
LISA Phasemeter: Thermal Design and Phase Readout Performance
On 25 January 2024, the LISA project was formally adopted by ESA as the next L-Class Mission in the Cosmic Visio Programme. The LISA mission´s primary objective is to measure gravitational waves in the 0.1 mHz to 1 Hz frequency band using heterodyne laser interferometry. The Phase Measurement Subsystem (PMS) is a core payload instrument responsible for the phase extraction of the interferometric signals with microradian precision. Achieving the necessary precision in thermal vacuum posed a significant technological challenge. Thermal noise in the sub-system interface with the platform couples into the phase and timing noise performance, potentially compromising the instrument’s performance. Therefore, the PMS thermomechanical design must effectively reducing thermal noise while complying with a flight instrument’s structural and reliability requirements. A flight-like PMS has been modelled, analysed, manufactured, and tested at the AEI in Hannover. The PMS performance was verified across different set points within its operating temperature range. Transfer function measurements were also conducted to determine the coupling coefficients between temperature and phase fidelity within the LISA observation band. This talk presents the latest results and upcoming activities.
Speakers: Ms Alicia López Jaén (AEI-Hannover), José Ogalde (AEI Hannover), Pablo Martínez Cano (AEI), Mr Sergio Lozano Althammer (AEI-Hannover)
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18:00
Cocktail Wintergarden
Wintergarden
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Thermal Analysis Einstein
Einstein
Convener: Alexandre Darrau (ESA)-
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Rationalization of Thermal Simulators for Operations
The proposed activity is focused on the rationalization of thermal simulators (here for operations) purpose based on existing thermal analysis model and tools. The idea is the re use of the thermal mathematical model all along the lifetime of the satellite, i.e. from the early design, the thermal analysis and control, the thermal tests on vacuum testing and the operations.
The idea is to share a common thermal model between thermal analysis and operations to allow a Spacecraft main constructor such as Thales Alenia Space to reduce the cost of the simulator implementation and increased its accuracy. The global scope is to rationalize all the thermal simulators during all the spacecraft lifetime. Today, the TAS spacecraft simulators for the functional validation (FV), software (SVF) and avionics, AIT benches have the same basis than the operations one but will not be addressed during this activity.
For this study Thales Alenia Space and DOREA choose Sentinel 3 as a study case because this satellite is already in flight and also because TAS is the manufacturer of Sentinel 3 especially the platform is well known.
A statement of work associated with a use cases study showed that having a reliable thermal simulator, allows the spacecraft constructor to validate the thermal control behaviour and the thermal margins, to correlate the thermal model with captured telemetry when testing the satellite in vacuum chamber, to correlate the thermal model in flight and many others interesting cases.
In 2022, with the financial and technical support of CNES, ESA asked to DOREA as Prime contractor and Thales Alenia Space as prime spacecraft manufacturer to implement a real time spacecraft thermal simulator demonstrator based on Sentinel 3B existing TVAC correlated thermal mathematical model in order to study the feasibility during operation use case in order to address after sales problematics during in flight missions such as energetic anomalies detection and in particular recovery testing by simulating new active thermal control characteristics.
This ESA/CNES study started with an ESATAN model including a STEP-TAS geometry provided by TAS Cannes. The presentation will show the technical locks such as the recovery of the telemetry, the initialization of the TMM temperatures based on this telemetry, but also the performances of such a simulator. This simulator has to provide a dynamic orbit propagator, a dynamic thermal regulator (PI regulation) and a dissipator especially for the platform (payload as boundary). The thermal simulator in parallel has to solve the radiative and thermal equation on the fly from a non-predictable scenario. Comparative results from a replay (7x faster than real time) will be demonstrated for the hot case and the associated telemetry.
After these results, the presentation will end with a roadmap of possible future activities in particular how to better estimate the dissipation of equipment units from telemetry and also possible future use cases demonstration.Speakers: Alexandre Darrau (ESA), Maxime ANDRE, Dr Thierry Basset (Thales Alenia Space), François Brunetti -
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Methodology and simulation of thermal noise in the frame of LISA IDS instrument performance test
The Laser Interferometer Space Antenna (LISA) mission is the first scientific space mission to detect and study gravitational waves from sources such as supermassive black hole binaries and intermediate mass black holes. Through a constellation of three spacecrafts orbiting the Sun and forming an accurate equilateral triangle in space of 2.5 million km long, these LISA spacecrafts exchange laser beams and measure their distance fluctuations (about 10-11 m) with their instruments MOSA (Moving Optical Sub Assembly) to detect gravitational waves. The launch is planned for 2035, on an Ariane 6 rocket.
Led by ESA, LISA is a collaborative effort involving ESA, its Member State space agencies, NASA, and an international consortium of scientists. CNES leads a community of French laboratories to jointly undertake major responsibilities in the mission and especially the performance test at CNES Toulouse of the MOSA instrument's metrological core named IDS (Interferometric Detection System). This test setup requires a dedicated development of thermal vacuum chamber and specific thermal test setup to minimize thermal noises impact from various ground and test sources: AIT room ambient temperature fluctuations, electronic temperature fluctuations, chamber active regulation, IDS thermal auto perturbations, harnesses, etc…
The main thermal objective and challenge of this IDS performance test are to achieve a very stable thermal environment with temperature fluctuations lower than 50 µK/√Hz at 30mHz and 20°C (no frequency domain analysis required). To anticipate the test setup design, CNES performs a methodological study to understand and evaluate the main drivers of thermal noise attenuation both by conduction and radiation using analytical studies. The numerical simulation of these thermal noise attenuations with high-precision calculations and associated interfaces for thermo-mechanical stability studies is also addressed. This involves software selection and recommendations in terms of modeling and approach (meshing and temporal convergence, noise wave propagation, reduced model integration, digit precision on output files etc…). This papers gives an overview of this methodology and simulation of the thermal noise attenuation to support the test setup thermal architecture of LISA IDS performance test.
Speaker: Maxime ANDRE -
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Leveraging Standardized Satellite Architecture For Thermal Analysis
Unlike traditional satellite companies, which often develop custom-build single purpose or very low volume satellites thermal control systems tailored to each mission, our approach at Loft Orbital involves the use of standardized platforms with generic thermal control systems. This approach is key for Loft value proposition which is driven by speed to orbit, cost and risk reductions.
By standardizing the Bus and Payload Accommodation Module (PAM) across numerous satellites, we were able to create a comprehensive dataset that facilitated the development of a surrogate model.
Our methodology begins by identifying key parameters affecting the thermal performance of the Payload Accommodation Module (PAM), such as power dissipation, component aging, seasonal variations, and altitude. We conducted a large set of simulations, systematically varying these parameters to assess their individual and combined effects on the thermal behavior of the system. This process enabled us to identify trends and quantify the influence of each parameter by isolating their effects on the thermal response. Using this data, we constructed a simplified thermal model that calculates temperature variations from a predefined baseline scenario.
This surrogate model was integrated into a user-friendly Python tool featuring an intuitive interface, enabling engineers across disciplines to input relevant parameters or extract them from power analysis data to perform initial thermal assessments without the need for specialized software.
This development enhances accessibility, increases efficiency, and leverages our approach to standardization to speed up the design process. By this approach we aim to reduce the time and resources required for comprehensive thermal assessments, aligning with our company’s goal of making space simple. This also empowers every system, mechanical, electrical or even business development engineers to quickly perform early phase thermal analysis suited to their needs.
Speakers: Adrien Feve (Loft Orbital Technologies), Ms Imane Karmoudi (Loft Orbital Technologies) -
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Trade-off of Optimization Algorithms for Space Thermal Engineering
Optimization algorithms for space thermal engineering play a crucial role in enhancing the performance and reliability of spacecraft thermal systems. A student from the University of Nice is exploring this topic in collaboration with Dorea Technology by utilizing optimization software tools such as Genetik+, developed by CNES, and GEMSEO, developed by IRT Saint Exupéry. The research involves testing various algorithms already integrated into these tools (genetic algorithms, gradient descent NELDER-MEAD, differential evolution...), focusing on their efficiency, accuracy, and computational demands. The goal is to identify the most suitable algorithms depending on the considered use case.
In this study the considered use case is the optimization of volumes for a satellite thermal gauging process, the results obtained through the duration of the internship are encouraging : several optimization algorithms used yield the correct remaining volume of propellant in an acceptable amount of time. Conclusions and future work will be discussed.Speaker: Mr Baptiste Pierron (University of Nice)
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Thermal Control Newton
Newton
Convener: Giulio Tonellotto (ESA)-
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Evolution of thermo-optical properties of solar panels or thermal control materials with lunar dust simulants contamination
The solar absorptance () and emissivity () are important engineering parameters to evaluate the performance of thermal control sub-systems or power generation at solar panels. In the context of future lunar missions, it is important to investigate the effect Lunar Dust Simulants (LDS) contamination on thermo-optical properties and thus performance of thermal and power functional surfaces.
In 2023, results from test campaigns performed on solar cell CoVerGlasses (CVG), Optical Solar Reflectors (OSR) and Second Surface Mirrors (SSM) after deposit of LDS have been presented.
This paper provides complementary data on paintings, coatings and MLI outer layers with the same LDS types (LHS-1 and LHS1-25A from Exolith Lab) and for larger range of Percentage Area Coverage (PAC or %cov) of LDS sub-monolayers (from 5 to 80 %).
The large available set of data allows for highlighting the main trends in response of emissivity and solar absorptance as a function of dust coverage. A metric is proposed to link dust coverage to degradation of solar absorptance and emissivity for all tested material. Finally the approach to account for LDS contamination with the thermal design will be discussed.Speaker: Dr Philipp Hager (ESA) -
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Adjustable Support Structure for Optical Sensors, ASSOSS - Thermal System
Adjustable Support Structure for Optical Sensors, ASSOSS - Thermal System
ASSOSS is a novel structure designed to provide structural support and efficient thermal management for optical space sensors, developed in a joint venture between Space Structures GmbH, BTU Cottbus-Senftenberg, and Fraunhofer IAP. This innovative project focuses on integrating ultra-lightweight materials, modularity in terms of height adjustment, number of sensors, and thermal strap design, along with high dimensional stability. The primary mechanical structure, research on efficient CFRP to CFRP joining technologies, and the development of a new lightweight thermal strap to transport heat from the optical sensor to the radiator were key development points. An outline of the design, manufacture, and testing of thermal strap and the system level thermal tests of ASSOSS will be presented in ESTEW 2024.
The thermal system of the ASSOSS focuses mainly on the thermal strap – radiator combination for effective heat transfer. The thermal strap was developed as a lightweight alternative to traditional copper-based systems to enhance thermal conductance while reducing mass in space applications. The development was done at BTU, Cottbus as a part of research activities. The developmental process included four key stages: material selection, thermal design, manufacturing, and testing. Graphite was selected for its excellent thermal conductivity and lightweight properties. During the design phase, the strap's configuration was optimized using hand calculations and finite element analysis to meet the ASSOSS project's geometric constraints and thermal requirements. Manufacturing faced challenges in bonding the delicate graphite foils, which were overcome by developing specialized techniques. A custom test rig measured the strap's thermal conductance in a vacuum chamber, confirming its effectiveness in managing thermal loads and validating the design phase results.
At the system level, the ASSOSS assembly is subjected to thermal simulations for radiator sizing and to analyze the performance of the system in orbit at different phases of the project. The initial analyses were done based on assumptions and later the data from the heat strap was included to simulate the unit more accurately. After successful tests of the thermal strap, it is then integrated into the ASSOSS system at Space Structures GmbH, Berlin. The complete system is subjected to thermal ambient cycling, thermal balance test and thermal vacuum cycling tests.
Speakers: Mr Carlos Saunders (Brandenburgische Technische Universität Cottbus – Senftenberg), Ms Shehna Sagaria (Space Structures GmbH) -
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Development of a Deployable Radiator Equipped with Loop Heat Pipes for high throughput communication satellites.
High heat-rejecting technology becomes increasingly necessary as communication capacity grows for the next generation of geostationary communication satellites. Engineering Test Satellite 9 (ETS-9) is being developed by JAXA to demonstrate bus technology for new high-throughput communication satellites and is scheduled to be launched in fiscal 2025.
The main technologies to be newly developed for the ETS-9 are high electrical power supplies, electric propulsion, and high heat rejecting technology. We have developed a deployable radiator (DPR) equipped with loop heat pipes (LHPs) and have completed qualification testing (QT). Since the DPR is equipped with a flexible heat transport device using LHP, it will unfold 180º after launch, efficiently dissipating heat from the satellite into space.The qualification testing included a deployment test and performance evaluation of heat-rejecting capacity. In addition to the qualification tests, we conducted long-term operation tests using a breadboard model (BBM) and tests in the microgravity environment of the International Space Station (ISS) and confirmed the design’s high reliability. A long-term operation test using the LHP-BBM determined that no non-condensable gas (NCG) was generated after high-temperature operation for six years and four months, from the end of May 2017 to the end of May 2024.
In this workshop, we will discuss the results of the DPR qualification test, and provide an overview of the long-term operation testing using BBM.
Speaker: Takeshi Miyakita -
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Multicase topology optimization for the thermal design of space systems
The thermal design of equipment and space platforms is a difficult task due to the large variability of the thermal conditions during the orbit and the strict constraints imposed by other subsystems. In the past years, several strategies have been studied to meet these constraints while reducing the signature of the thermal control subsystem. These techniques encompass different algorithms that give the optimal placements of the components in the platform. When this relocation is not possible, another alternative is to modify the thermal couplings between the components, obtaining a more efficient heat distribution. To achieve this, topology optimization, originally linked to lightweight structure optimization, has been extended to heat transfer problems. Nevertheless, the influence of thermal radiation has been rarely taken into account in this context. In addition, most formulations are based on a finite element discretization, whereas most commercial software for heat transfer problems use the Lumped Parameter Method. This paper aims to extend the topology optimization framework to overcome the aforementioned issues. An optimization algorithm based on the Heaviside Projection Method is developed to optimize the conductive paths of two-dimensional space structures. The performance of the algorithm has been studied by optimizing a multi-case objective using a Printed Circuit Board. The method is used to generate the optimal shape of an additional copper layer so that the components on the board satisfy specific thermal requirements simultaneously for a hot and cold case. Results show a significant improvement in the thermal compliance of all the components with the addition of the high conductive layer. Moreover, a reduction method is introduced to transfer the material distribution from the optimization to a coarser mesh of any size, which is useful to facilitate its implementation in existing software, where a large number of degrees of freedom can be a limitation.
Speaker: Carlos Arroyo Ruiz (Universidad Politécnica de Madrid)
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11:00
Coffee Break Einstein and Newton
Einstein and Newton
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Heat Transport Einstein
Einstein
Convener: Dr Paolo Ruzza (ESA)-
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Guidelines for the use of Aluminum Grooved Heat Pipes (AGHP) with non negligible gravity effects
Extruded Aluminum grooved heat pipes are the most widely used components for the thermal management of spacecrafts, including high performance, high reliability level with large space flight heritage and market availability. This technology is designed and optimized to operate in micro-gravity and the gravity effects on Earth and during lunar or planetary missions significantly affect the performance of the grooved capillary wicks. With the aim of supporting the sub-systems or satellites acceptance testing on Earth as well as providing useful guidelines to design grooved-heat-pipe-based thermal buses for planetary missions, the proposed presentation intends to explain how to take benefits of the gravity to secure the aluminum grooved heat pipes operation. This analysis leads to discussions and operational guidelines to design efficient thermal buses based on Aluminum Grooved Heat Pipes (AGHP) in such environment. A technical solution is proposed and dedicated thermal test campaign has been realized to validate the proposed approach.
Speaker: Dr Mikael Mohaupt (Lead Design Engineer at EHP) -
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A review of variable conductance heat pipes for planetary surface vehicles and deep space missions
Heat pipes are conventionally used for spacecraft thermal control. A well-designed heat pipe provides a reliable thermal link that transports large quantities of heat at nearly isothermal conditions, varying its working temperature and pressure within its design range to adapt to the conditions of the heat source and sink. However, heaters are often used in the cold non-operational phase to compensate for this efficient thermal link and ensure the survival of sensitive hardware in the extreme cold, which consumes part of the spacecraft power budget.
Planetary rovers and deep space missions experience large fluctuations in environmental conditions, including long periods of extreme cold (e.g., lunar and Martian nights, or long cruise phases) with limited available spacecraft power. Thus, it becomes beneficial to implement variable thermal links that can passively adapt to maintain stable spacecraft equipment temperatures. This includes passive thermal switching, where the link is terminated during long cold phases, maintaining acceptable equipment temperatures with minimal heating power.
The variable conductance heat pipe (VCHP) presents a potential solution. Variable conductance can be achieved in several ways. Most commonly, the active area in the heat pipe condenser is partially blocked by flooding with a non-condensable gas. Other control schemes include condenser blocking with excess working fluid, or the control of vapour flow to the condenser, or liquid back to the evaporator.
In this presentation, the various design schemes for VCHPs are discussed. Emphasis is placed on the hot reservoir VCHP, which builds upon flight heritage from the cold reservoir VCHP previously flown as part of the European SIGMA instrument. The improved hot reservoir design eliminates the need for heating during cold phases, making it particularly suitable for planetary rovers and deep space missions. The current TRL for this technology, along with its strengths, limitations, and design challenges, are examined. Additionally, a potential thermal modelling approach using ESATAN TMS is suggested, focusing on capturing the physics of variable conductance within the TMM.
Speaker: Ashraf Al-Bahlawan -
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MICROGRAVITY FLOW BOILING HEAT TRANSFER ENHANCEMENT VIA FEMTOSECOND LASER TEXTURED MICROFEATURES
Designing efficient cooling devices is crucial in a multitude of applications. Although advanced cooling technologies have existed for decades, there is still a lack of more efficient heat dissipation methods, especially for space applications where thermal management devices must dissipate heat in reduced gravity. Flow boiling presents here a first significant improvement over traditional single phase cooling systems, as it makes use of the significantly larger latent heat of a fluid. The performance of flow boiling can even be further improved by functionalizing boiling surfaces, which is currently a key area of research. These functionalized surfaces can lead to more controlled and more dense nucleation as well as controlled rewetting of the surface, resulting in higher heat transfer coefficients, reduced flow instabilities and increased critical heat fluxes.
In this study, we evaluate the change in bubble dynamics and heat transfer performance for three different types of surface textures produced on 200 μm thick 316L SS foils using a femtosecond (fs) laser. The investigated textures include microscale grooves and conical holes with a tilted (= 45◦) geometry. In addition, we also evaluate the effect of laser-induced periodic surface structures (LIPSS), which are sub-micron scale features fabricated by fs laser processing. Results are compared between terrestrial and microgravity conditions to compare heat transfer enhancement degrees of each textured surface with respect to a plain reference surface in the same operating conditions. The fluid used is PP1, a replacement of 3M™ FC-72 in heat transfer applications. Microgravity data was gathered on the 83rd ESA Parabolic Flight Campaign. It was found that the enhancement degrees were reduced in microgravity with respect to terrestrial conditions, but overall trends remained the same for each surface, showing op to 20% improvement in HTC over a plain surface in microgravity. So, the performed experiments showed clear potential for the application and further investigation of textured boiling surfaces to be employed in microgravity flow boiling cooling systems.
Speaker: Frederik Mertens (KU Leuven)
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Thermal Design Newton
Newton
Convener: Paula Prado Montes-
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Development of a Compact Lightweight Micro-Channel Heat Exchanger (MCHX) for Reusable Launch Systems
Microchannel heat exchangers (MCHXs) have been the focus of intense study in the academic sector for around 20 years, with an escalation in recent times due to the severe heat management issues associated with current and emerging applications in technology areas such as energy production and space. The space sector, in particular, is implementing thermodynamic cycles in what can be considered very high temperature and high pressure environments. One such example is the thermodynamic cycle of the Synergistic Air Breathing Rocket Engine (SABRE), a hypersonic precooled aero-engine developed by Reaction Engines Ltd. SABRE is unique among rockets since it can operate both as a turbojet engine (air breathing) and a conventional rocket, and in such applications, extreme pressures and temperature differentials are present.
In a project supported and funded by the European Space Agency (ESA), work was carried out where the overarching technical objective was to develop and validate a compact, light-weight and high performance helium-hydrogen heat exchanger model, based on computational fluid dynamics (CFD) and analytic theoretical models. The validated model was then used to provide the basis for an HX concept used in the power management system of a reusable launch system. The main technical objective was to increase the thermal performance of the MCHX to achieve a Nusselt number of over 10 (Nu>10). This is primarily achieved through the addition/modification of geometrical features and channel arrangement, and through adoption of a cross-flow H2-He design as part of a wider Brayton heat cycle concept.
A practical design case scenario is considered, whereby 35K Hydrogen at 20MPa is used as the coolant in a MCHX that must transfer close to 90MW of heat whist ensuring a 42K outlet temperature for the initially 700K Helium. The model results indicate that substantial size and weight reduction will be achieved provided that specifically engineered microchannels can be manufactured at the sub-micron scale. The resulting MCHX was designed such that it could be manufactured using photochemical etching to form the micron-scale channels on individual shims, which are then stacked and diffusion bonded to produce 316L stainless steel MCHX breadboards for the on-going validation programme itself. This method of manufacture produced what are commonly known as a printed circuit heat exchangers (PCHEs). With high strength, leak-tight bonds, good chemical compatibility whilst being compact and lightweight nature, lends themselves well to the extreme service conditions as outlined, whilst achieving the desired heat transfer goals.
Speaker: Mr Kandarp Amin -
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Thermal design and analysis of FLEX spacecraft
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.
Speaker: Adeeb Nazeeruddin -
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Advanced Thermal Control for Space Payloads: A Multi-Processor Approach
Optical instruments in space payload systems face challenges in maintaining minimal temperature gradients to prevent optical bench deformation, which can impair optical paths due to component sensitivity. The heat generated by payload components and processor units adds to the overall thermal load. To address this, a multi-processor system can distribute generated power, or heat, by shifting tasks among processor units. Further, other subsystems, e.g. thermoelectric coolers, are controlled by the processor units. Despite introducing heat points, the control of redundant subsystems offers design freedom for optimizing the thermal distribution on a payload platform.
By utilizing the flexibility in subsystem control, a multi-processor system can minimize temperature gradients. Model predictive control, informed by orbit temperature patterns, can enhance thermal management. The Processor Layout Utilization for Thermal Optimization (PLUTO) project is a co-funded project by the Bavarian Ministry, led by Engineering Minds Munich. It aims to develop thermally optimized layouts for payload subsystems and processor units, using intelligent control based on orbit temperature data. A demonstrator payload with three interconnected processor modules will verify the thermal model, with testing scheduled for end of 2024.
This collaborative project between the space industry and universities seeks to improve thermal management in space payload systems, enhancing the performance of optical instruments.Speaker: Jintin Frank
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13:00
Lunch ESTEC Restaurant
ESTEC Restaurant
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Thermal Analysis Newton
Newton
Convener: Matthew Vaughan (ESA)-
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Predictive Modeling of Thermal Interfaces for Space Applications
Developing an understanding of thermal interface conductance is critical to managing an accurate spacecraft thermal balance. However, the real performance of assembled interfaces is often not well understood until the systems have been built and tested in vacuum. To facilitate more predictive design for space applications, Carbice Corporation has developed a suite of modeling tools that quickly provide accurate assessments of interface performance by solving the mechanical structural problem at the interface to determine the deflection of the components under load. When applied to an interface that adopts an elastic interface filler like the carbon nanotube based Space Pad line of products, an accurate assessment of contact pressure distribution within an interface can be determined, along with the resulting thermal map. This presentation will walk through several examples of real thermal interfaces that have been modeled using the Carbice SIM toolset along with experimental data validating model predictions. The presentation will then show model prediction for an actual Thales Alenia Space (TAS) traveling wave tube (TWT) application, showing the SIM tool’s performance predictions validated by actual TAS test data measurements.
Speaker: Mr Erik Anderson (Carbice) -
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Development and Implementation of a Python GUI for Efficient Management of ESATAN-TMS Thermal Models
A Python-based Graphical User Interface (GUI) has been developed to enhance the system management of ESATAN-TMS thermal models through a hierarchical structure. This innovative tool enables users to create and modify model structures seamlessly, perform various tasks at both system and unit levels, and efficiently import/export tasks. Additionally, it facilitates the establishment of a collaborative repository with version control, ensuring smooth and coordinated teamwork. The tool offers automatic configuration of execution and post-processing tasks through preconfigured functions, significantly streamlining the workflow. This approach, combined with the methodology proposed, results in substantial savings in resources and engineering time. The proposed structure has been successfully implemented in several high-profile projects, including SUNRISE III, the Ariel telescope assembly, COMET-I Probe B2, Vigil PMI E-Unit, and UPMSat-3. These implementations have demonstrated the tool's effectiveness in managing complex thermal models and improving overall project efficiency.
Speaker: Javier Piqueras Carreño -
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Linearization of the Radiative Component of the Heat Transfer Equation for Space Thermal Analysis
When dealing with thermal simulation, the time constraint represents a significant challenge, particularly with the rise of thermal digital twins. To address this, an approach relying on the linearization of the radiative component of the heat transfer equation is being investigated as a potential replacement for the Runge-Kutta scheme. A student from the University of Nice, in collaboration with Dorea Technology, has undertaken this task to simplify the non-linear nature of radiative heat transfer. By approximating the radiative heat exchange between surfaces in space as linear, the study aims to enhance the computational speed of solving the heat transfer equation. This advancement would allow for more precise control and prediction of thermal behaviors in spacecraft, ensuring better performance and reliability in the harsh conditions of space.
Speaker: Mr Charles Fabre (University of Nice) -
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Comprehensive Thermal Management Analysis for NUSES and WINK Space Missions Using COMSOL Multiphysics
The NUSES (Neutrino and Seismic Electromagnetic Signals) is a mission to explore new scientific and technological pathways for future space-based detectors which aims to advance the study of high and low-energy cosmic radiations using two primary payloads: Zire, which detects gamma rays and charged particles, and Terzina, a telescope designed to test new observation techniques for studying ultra-high-energy cosmic rays and neutrino astronomy by detecting atmospheric Cherenkov radiation. Yet another, the WINK is a pioneering project for gamma ray detection in space which is being developed for a pathfinder mission onboard the ESA Space Rider vehicle. This study investigates the thermal management strategies and thermal expansion effects in these multiple space missions, focusing on the Zirè payload, Low-Energy Module (LEM), and the overall NUSES satellite, along with preliminary thermal analysis for the WINK Space Rider project. Using COMSOL Multiphysics, comprehensive thermal simulations were conducted to ensure the thermal stability and reliability of satellite components under varying conditions. For the Zirè payload, simulations for the electronic box and detector system demonstrated stable thermal performance and effective heat dissipation. The LEM's analysis emphasized the importance of material selection, power consumption, and surface emissivity in maintaining optimal temperatures. A holistic thermal model for the NUSES satellite ensured safe operational temperatures for integrated payloads, simulated in orbit. Preliminary results for the WINK project highlighted the impact of thermal decoupling and contact resistance on temperature regulation. Additionally, the potential effects of thermal expansion were assessed, showing that displacements were within acceptable tolerances for the materials used, ensuring structural integrity. These findings validate the effectiveness of the implemented thermal management strategies, crucial for the reliable performance of satellite missions in space.
Speaker: Uygar Atalay
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38
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Thermal for surface missions Einstein
Einstein
Convener: Dr Philipp Hager (ESA)-
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Design of an Actively Shuttered Dust-Resilient Radiator for Lunar Applications
The Moon presents an extremely harsh environment for robotic and human exploration, with diurnal temperature cycles spanning nearly 300°C (-150 to 120°C). Active thermal control is widely regarded as a key technology to enable surface assets to survive the lunar night. We report on progress in the development of a compact and scalable, actively shuttered radiator, designed to be resilient to the dusty environment that will be encountered by many upcoming lunar missions, such as Argonaut/EL3. The radiator's function is influenced by extreme temperature variations, where thermal cases must consider solar input and IR heating from the surface during the lunar day as well as heat losses during the lunar night. An actively shuttered approach enables closure of the radiator to minimize heat losses at night and/or to protect the radiator from contamination during events with high expected dust deposition, such as landing, astronaut, rover, or robotic activities, or the passing of the day/night terminator.
To maximize functionality across a wide range of lunar scenarios, with an emphasis on polar regions including lunar landers, payloads, and rover applications, our approach has adapted a heritage shutter concept previously flown on Rosetta and Giotto missions. Over the two past years, we have validated new dust-resilient elements via component-level breadboard activities and conducted thermal vacuum tests on Engineering Model to correlate with our thermal model. An overview of the Engineering Model design is provided, highlighting thermal design choices as well as the thermal verification approach. This includes detailed results from the thermal vacuum tests, comparison with simulated load cases demonstrating the reliability and effectiveness of the radiator system under simulated lunar conditions.Speaker: Angel Iglesias (Almatech SA) -
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Thermal challenges in the deployment of an Environmental Network on the Mars Surface through miniature probes.
Over the last decades, several missions have successfully landed on the Mars Surface, placing scientific instrumentation onboard landers and rovers in different individual landing sites. However, a qualitative leap in “in-situ” climate science on the red planet could happen via larger-scale observations. MarsConnect is an INTA project that aims to develop microprobes with scientific instruments that, thanks to their reduced mass and volume, could be deployed on the Martian surface in a large number to set up planetary atmospheric networks.
The 10-12 kg probe consists of a rigid aero-shell that provides both stability and heat shielding during the descent, avoiding the complexity of supersonically deployed parachutes, propulsion systems or inflatable technologies. Aerothermal loads during the re-entry phase drive the sizing of the Thermal Protection System (TPS), that guarantees the probe’s structural integrity and proper internal temperatures. Preliminary conservative estimations for a range of trajectories and atmospheric conditions yield figures at the stagnation point of 210 W/cm² for peak thermal flux and of 10.000 J/cm² for integral thermal load.
The aeroshell encloses a ~6 kg, 3-section, hard impact penetrator (terminal velocity < 140 m/s), that can accommodate up to 1 kg of payload. Once on the Mars surface, most of the equipment relies on its wide allowable temperature range, heritage of the miniaturized instrumentation already qualified for past missions to Mars. The penetrator also includes a highly insulated “warm compartment” for components required to be maintained within more stringent limits. The landing site latitude will determine the illumination profile along the Martian year, and hence the maximum available power that can be obtained by the lander solar cells and the necessary storage capacity of the batteries to survive the Martian night.
The current talk will describe the different thermal environments throughout the mission that are critical for the dimensioning of the Mars Connect probes as well as provide a glimpse into the preliminary design concepts proposed in the frame of the project feasibility study.
Speaker: Alejandro Gonzalo (INTA) -
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Design Improvements on the Active Thermal Switch
With the growing interest in lunar missions during the last few years, the demand for technologies which allow hardware to survive the extreme conditions of the lunar night has increased. One promising approach is to enable high performance bi-directional thermal control in space applications.
Lunar Outpost EU has continued the development of the active thermal switch (ATS). The compact device allows to actively change the thermal conductance on-demand between a heat source and sink from a low to a high value and vice-versa.
A new version of the active thermal switch was tested in summer 2024. Based on the design changes carried out it was possible to improve the main performance characteristics. Additionally, further technical improvements were identified.
To describe the system performance more accurately, the novel method of calculating the Turn Down Ratio (TDR), which was presented during the ESTEW2023 is being used.
Speaker: Tobias Flecht (LunarOutpost EU)
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42
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16:00
Coffee Break Einstein and Newton
Einstein and Newton
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Thermal Analysis Newton
Newton
Convener: Duncan Gibson (Telespazio BE for ESA)-
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Update on thermal analysis and data exchange activities in ESA Newton
Newton
Speaker: James Etchells -
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Optimization of detailed Cubsat thermal model coupled with system power budget analysis Newton
Newton
This presentation will go through a cubsat design workflow, from the system level power system design and coupling it with our detailed thermal model directly using the FMI standard. We will show how the orbit/mission planning can be imported from GMAT. And finally we will optimize the whole system with a multi objective design study focusing on reducing mass, but making sure our power generation, storage and temperature control are maintained.
We will be using Simcenter Amesim for the power system modeling, Simcenter 3D Space Systems Thermal (TMG) for the detailed thermal model and Simcenter HEEDS for the optimization and automation workflow.
Speaker: Jean-Frederic Ruel (Maya HTT) -
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Efficient Integration of Space Thermal Analysis Model Newton
Newton
The spacecraft design activity usually involves the collaboration of many different teams with various process, methods and tools. Despite the universality of thermal data (temperatures, fluxes, …), every thermal analysis software have their own specificities, which makes the exchange of thermal data often challenging.
Besides data format standardization initiatives (ECSS, STEP-TAS, …), other approaches can be investigated to facilitate the exchanges between thermal engineers. The “Efficient Integration of Space Thermal Analysis Model” project, conducted by ESA along with Airbus DS, Epsyl and Ariane Group, aimed to identify and test innovative solutions to tackle this type of situation.
A survey was sent to 38 space actors, including spacecraft, subs-systems and launcher manufacturers from 15 different countries, to identify user requirements. The analysis of these requirements has led to the selection of the FMI co-simulation solution. The Functional Mock-up Interface (FMI) is a free standard that defines a container and an interface to exchange dynamic simulation models as FMU (Functional Mockup Units). This standard is commonly used across several industries to perform co-simulation, regardless of discrepancies in software and physics at stake.
A preliminary implementation of Systema FMU wrapping combined with a co-simulation solution developed by Epsyl enabled the demonstration of the feasibility (TRL3) of performing thermal to thermal co-simulation through FMI. The numerical accuracy of the co-simulation was assessed by basic theoretical cases while the interest of the solution was evaluated through a set of industrial cases including satellite-launcher coupling and satellite sub-systems integration.
This presentation comprises a summary of the achievements, challenges and lessons learned of FMI-based thermal data exchanges as well as discussions on way forwards for future developments.
Speakers: Antoine Caugant, James Etchells
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Thermal Control Einstein
Einstein
Convener: Marc Broussely (ESA)-
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IMPROVEMENT OF ANTENNA THERMAL RADIATORS EFFICIENCY USING AN INNOVATIVE TAPE AS OPTICAL SOLAR REFLECTOR
Spacecraft antennas are always directly exposed to the space environment. Suitable choice of materials and processes is the basis of successful performance.
Active Antennas with very high dissipative units have to be thermally controlled in order to guarantee that the temperatures of all items will remain below the upper limits with appropriate margins. One option is to use suitable radiators. Once the radiator location and the thermal resistance between the dissipating components and the radiator are known, its size has to be determined to reject the foreseen heat dissipation. In order to maximize heat rejection of the radiator, thermal engineers choose coating materials with high emissivity. The heritage of the aerospace industry is the use of optical solar reflectors, which allow improving the heat rejection capability of the external radiators while reducing the absorption of external solar fluxes.
In the frame of an antenna thermal design of a 15-years mission in GEO environment, it was necessary to find mass-saving alternatives to OSRs, while obtaining a very efficient radiator thermal behavior. This alternative is represented by First-Flex by CREO, a new type of polyimide flexible tape developed in the frame of ARTES program, made of a multi-layer coating on the space-facing surface and characterized by low absorption (alpha) and high emissivity (epsilon).
This paper presents the comparison of the antenna thermal performance between First-Flex tape and other heritage optical solar reflectors for space applications, while also highlighting the improvement from the overall design point of view and in particular the mass reduction achieved. #Speaker: DIANA SCIULLI (THALES ALENIA SPACE ITALIA) -
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The development of First-Flex, a new flexible Optical Solar Reflector
Optical Solar Reflectors (OSRs) constitute the physical interface between radiator panels and outer space and allow for radiative cooling of the spacecraft. The performance of an OSR is defined mainly by two Thermo-Optical (T.O.) parameters: solar absorptance α (the lower the better) and IR emittance (the higher the better). The market of OSRs is dominated by OSR quartz tiles, and by flexible Second Surface Mirrors (SSMs). Quartz OSRs exhibit excellent T.O. properties and durability, but are expensive and tend to break during assembly, integration and testing. Conversely, SSMs are easy to handle and apply, but age rapidly in space, due to the effects of UV radiation, charged particles and atomic oxygen on the polymeric film.
First-Flex is a brand-new OSR technology that aims at combining the performance and durability of quartz OSRs with the flexibility and easy handling of SSMs, at fair costs. First-Flex consists of a fully inorganic coating sputter-deposited onto the first surface of polyimide tape. The coating provides the required T.O. properties, while the substrate remains protected from the environment and serves only as mechanical support for the coating. First-Flex stems from a study for the Bepi Colombo mission, that led to the development and qualification of an extremely durable white coating named ‘Interferential CERMET’ (IC), now flying to Mercury on the High Gain Antenna feed of the MPO. Subsequently, in the frame of the ESA ARTES AT and C&G programs, the IC coating was transferred from rigid metal substrates to polyimide tape, to be used as a flexible OSR. This paper reports on the final stages of development and industrialization of the technology and includes, in particular, the results of qualification tests for the application of Fiirst-Flex in various environments, including GEO.Speaker: Sandro Mengali (Consorzio CREO)
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18:00
Workshop Dinner ESTEC Restaurant
ESTEC Restaurant
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Heat Transport Newton
Newton
Convener: Dr Paolo Ruzza (ESA)-
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Oscillating Heat Pipe for Commercial Space Applications: Reliability and Flight Heritage
The oscillating heat pipe (OHP) is an emerging passive heat transport technology for satellite thermal management. The OHP is similar to other heat pipes in that it uses a saturated fluid to transport heat, however its operational mechanism relies on bubble nucleation in a capillary channel to pump liquid and vapor between the heat sources and heat sinks. This design enables the OHP to be constructed in thin, light weight, structural form factors that can transport high heat loads and fluxes. In the last decade, the OHP has undergone significant testing on ground and in orbit through a number of space agencies and companies. In addition, significant effort has gone into developing accurate models to predict OHP performance and operational limits. Due to these advances, OHPs have begun to be used in commercial satellite applications and have over 300,000 hours on-orbit. These OHPs are used in a variety of form-factors such as heat spreaders, transporters, and radiators. In addition, due to their design, they sometimes also serve as a structural member of the system. This presentation will focus on OHP applications for commercial satellites including operational characteristics, thermal and structural reliability, and space flight heritage.
Speaker: Corey Wilson (ThermAvant Technologies) -
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Testing of the chemical compatibility of two-phase devices composed by Aluminum and Stainless-Steel materials with Ammonia as working fluid operating at high temperatures
Two-phase cooling systems are relying on the high efficiency of the fluid phase change to store and transport the heat (latent heat). The operation of these systems needs to control the saturation conditions with very high accuracy and without discrepancy during the lifetime of the cooling system. This lifetime can be from 5 years up to 20 years or more, including storage and operation time. In that context, the chemical compatibility of two-phase cooling devices is of primary importance due to severe impact on the performance of the thermal transfer function. These devices are tight-closed systems, and no maintenance can be performed over the lifetime, requiring a high level of criticality for the validation of a stable chemical compatibility. Indeed, the closed internal environment needs to avoid the generation of non-condensible gases leading to a change in the saturation conditions and thus, in the final operating parameters and performance of the two-phase devices.
The proposed presentation exposes the tests performed in the configuration with aluminum and stainless-steel using ammonia as working fluid. The test has been performed over a long time at an operating temperature over 80°C. The observed results are discussed.Speaker: Dr Mikael Mohaupt (Lead Design Engineer at EHP)
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50
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Thermal Analysis Einstein
Einstein
Convener: Arthur Dunlop (ESA (ESTEC))-
52
Pycanha: An Open-Source Tool for Thermal Analysis
Pycanha is a new open-source tool designed for thermal analysis, utilizing the lumped parameter method. Developed primarily in C++ and Python, Pycanha combines the strengths of both languages: critical components, such as data structures and solvers, are implemented in C++ for performance optimization, while the user interface is facilitated through Python for ease of use.
Pycanha has been made from the ground up for high performance and broad compatibility, leveraging modern features of both C++ and Python. The TMM solvers are executed on the CPU, using the latest versions of state-of-the-art high-performance algebra libraries. On the other hand, radiative calculations are handled on the GPU using the Vulkan library, making it compatible with different GPU vendors that support ray-tracing acceleration.
Despite its focus on high performance, Pycanha also emphasizes usability. It is operating system-independent and can be installed as a standard Python package, so it can be easily integrated within user applications. This flexibility allows for advanced analyses, including parameter influence studies, model correlation, and model reduction, making Pycanha a powerful tool for comprehensive thermal analysis.Speaker: Javier Piqueras Carreño -
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Accelerating Aerospace Development through Ansys Thermal Desktop
Ansys Thermal Desktop (TD) is software for heat transfer analysis, thermal radiation, environmental heating, and fluid flow design. One of the features that make it unique is its comprehensive two-phase capabilities, along with an Advanced Design Module. This module supports parametric studies, design optimization, and model correlation making Thermal Desktop a versatile tool for component and system design. These capabilities make Thermal Desktop a critical tool for any thermal/fluid engineer.
The latest release, TD 2024 R2, introduces several innovative features aimed at enhancing user productivity and streamlining workflows. Key improvements include performance enhancements that offer up to four times faster thermal solution analysis. This latest version includes axisymmetric modeling, which provides the corresponding tools to mesh and simulate axisymmetric geometries. Additionally, the updated interface delivers a more straightforward and direct user experience. Enhanced coupling capabilities with other simulation software allow for more complex fluid and thermal analyses. These and other new features included in this release enable users to achieve more efficient workflows and simulations, reinforcing TD position as a leading software for thermal analysis.Speaker: Monica Ramirez Lastra (Ansys) -
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ESATAN Thermal Modelling Suite - Product Developments
ESATAN-TMS provides an advanced thermal modelling environment for the thermal analysis of spacecraft and launch vehicles. The suite is continually being enhanced to meet current and future requirements of space projects, and to support the specific needs of thermal engineers. This presentation will focus on the latest development to be included in the coming ESATAN-TMS 2025.
Speaker: Henri Brouquet
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52
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11:00
Coffee Break Einstein and Newton
Einstein and Newton
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Thermal Analysis Einstein
Einstein
Convener: Alexandre Darrau (ESA)-
55
Benchmarking Radian: a cloud-based thermal analysis software
Radian is a thermal analysis software conceived to provide agility to engineers, both at modelling and computing processes. Our software is accessible through a regular web browser and counts on a scalable network of computing resources in the cloud. Thermal analyses are supported by the Databank, a catalogue of satellite components and other reusable entities. Thermal models are based on a wide range of geometrical primitives, which are selected within the tool or imported and simplified from a CAD file. The underlying simulation engine reproduces the orbital environment and the thermal solution.
Over the course of 2024, as part of the ESA BIC Madrid incubation program, our team has compared the results computed by our simulation engine with other tools of varying purpose. Intially, we have assessed the Radian routines that compute direct radiative heatfluxes in orbits around the Earth against ARTIFIS and TOPIC, two well-tested legacy tools provided by the European Space Agency. In the second stage, we assessed the outcome of complete thermal analyses provided by Orora Technologies and performed in ESATAN-TMS, a robust and widely adopted commercial solution. These activities have counted with the support and guidance from the Thermal Analysis and Vertification Section of the European Space Agency.
Furthermore, several new features have been included both in the user interface and the simulation engine (e.g. additional parameters and setting proxies for scenarios, wider configurability of geometries and cutouts).
Speaker: David Criado -
56
Thermal Correlation of Reduced Models Using an Adjoint-Based Solver
The current trend in the space industry is to create less expensive satellites in shorter periods of time. In such context, space systems thermal analyses require dealing with models with different levels of fidelity. Detailed thermal mathematical model (TMM) can imply high computational cost due to the complexity of the orbital environment of the missions, but also due to the many iterations that are required to be run in thermal design processes. Thus, low-fidelity or reduced-models are generally developed and used to shorten analysis time. The main challenge with building a reduced model is to have the right level of accuracy while having the smallest possible computational time compared to a detailed model. Indeed, when simplifying a thermal model, one needs to make assumptions and to ensure that the model gives the right predictions at critical locations. Thus, space thermal engineers must correlate reduced and detailed models before using a reduced model for the multiple operating conditions involved in a mission analysis.
In this presentation, we will introduce an automated and efficient method of correlating and calibrating a reduced-thermal model with a detailed model using an adjoint-based solver implemented in the TMG Correlation tool. It takes advantage of the adjoint-based formulation of the energy equation to get the variation of an objective function, which represents the temperature difference between the reduced and detailed models at specific locations, with respect to the design variables of the correlation/calibration problem using a single solve of the thermal problem. By combining this adjoint-based solver with an optimization algorithm, the correlation/calibration procedure can be automated and performed much faster than using a manual procedure.
The presentation will first describe the adjoint-based approach used for model correlation. Then, the detailed and reduced models of a spacecraft sub-system will be described. Using the adjoint-based approach, we will correlate and calibrate the reduced model with the detailed model results. Finally, we will discuss the results and give some perspective of work for calibrating thermal reduced models.Speaker: Jean-Frederic Ruel (Maya HTT)
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55
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Thermal Design Newton
Newton
Convener: Andreas Mussger (ESA)-
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High Temperature Power Supply For Solid State Power Amplifiers
This presentation addresses the main architecture and technological investigations performed in the frame of a new power supply for solid state power amplifiers compatible with baseplate reference temperature of 85°C. This power supply module has been studied by Thales Alena Space Belgium R&I department, supported by an ESA contract (ESA AO/1-10209/20/NL/CLP).
Main mechanical and thermal design difficulties and technological choices linked to high temperature aspects are presented as well as thermal vacuum tests and comparison with predicted temperatures.In a telecommunication satellite, this power supply unit (PSU) is functionally located between the antenna (containing the solid state power amplifiers, “SSPA”) and the electrical power system (EPS). Its main goal is to provide several adjustable power sources for the SSPA system as well as required auxiliary supplies. This unit is composed of several power modules, each one capable of providing 1kW. Depending on satellite architecture, this PSU could be located close to the antenna, possibly in a location regulated at higher temperature than usual for that kind of power supply unit.
Indeed, maximum reference temperature could reach 85°C at thermal reference point. This has a strong impact, especially on electronic components and materials (solder joints, PCBs…), and made this module a good candidate for investigating the different technologies linked to higher temperature.In order to limit the impact of this increase of reference temperature, the technology selection objectives are to minimize the thermal path between the dissipative components and the heatsink and to use “high temperature” compatible components and materials.
In that frame, components were selected based on their ability to work at high temperature with a minimum rating of 125°C. COTS components (compatible with automotive standards) were used for cost optimization as well as space grade components when required (need of radiation hardened for example).
For the power part of the modules, an Insulated Metal Substrate (IMS) technology combined with classical PCB was selected. The key advantage of this architecture is to combine thermal performance of the IMS substrate and the capability of the PCB for the use of components like Ball Grid Array (BGA) for GaN transistors control and driving.
A thermal gap filler has been used between the IMS and the structure allowing to have a good thermal path while dealing with the different mechanical tolerances.
Moreover, particular care has been taken to define assembly processes of the components on the IMS and PCB. Analysis and tests have been performed to assess reliability of solder joint connections submitted to high temperature and thermal cycling.A thermal model of the module has been build and analysis were made in order to assess the compliance of the architecture with the requirements.
Finally, an EM model of one module has been manufactured and tested in TVAC conditions. This allowed to compare predicted temperatures with measurements.
Tests performed on the EM model and on its technological constituents allowed to reach a TRL level of 4 at the end of this project confirming the possibility to use associated technological building blocks for future developments.Speaker: Jérôme Garnier (Thales Alenia Space Belgium) -
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JUICE PEP NU thermal analysis with flight telemetry
The Particle Environment Package onboard the JUICE mission is designed to measure neutral and charged particles in the Jupiter system. Being a particle spectrometer, its temperature should be higher than the JUICE spacecraft to minimize contamination by outgassing.
Therefore, several back-out periods with nominal and redundant instrument heater turned on are foreseen during the 8 year long transfer to Jupiter. The upcoming hot mission phase during Venus FlyBy in 2025 is of particular interest for reaching maximum temperatures.
To increase confidence in thermal analysis predictions, the bake out phases so far were recreated by importing telemetry data of heater status and instrument dissipation into the thermal model.
A brief overview of the PEP NU thermal design is given, followed by its thermal history in space so far. The challenges in obtaining the correct telemetry data and strategies to cope with missing current/ temperature reading calibrations are presented.
Speaker: Sebastian Wolf -
59
A STOP Analysis workflow. Application to a lunar satellite
The behavior of optical instruments on a satellite performing observation missions is critical, especially for scientific purposes where measurements stability is essential for data validity. However, accurately characterizing the impact of the environment on lenses is complex.
Conducting robust and accurate Structural Thermal and Optical Performance (STOP) analysis can be challenging and time-consuming, often requiring manual transfer and optical modeling through multiple software packages or in-house codes. We propose a solution that interconnects several programs, starting from the orbital mission model to optics and thermo-stress analyses, to better understand the impact of the environment on the system.
During a previous study the nominal optical train of a standard 3U Cube Sat was designed for a LEO. However, to obtain similar results when the satellite orbits the Moon, further development and additional components like heaters could be necessary for the successful completion of the mission.
To perform the analysis, first, a lunar orbit is chosen for the satellite based on the region of the moon to be monitored. That orbit is then imported to calculate the thermal behavior of the satellite, including the environmental heat loads. The resulting temperatures are mapped to a mechanical model, to obtain the thermal stresses in the structure and optics. Finally, the thermal and deformation results are imported back to the optical tool, where the impact on the optic train is studied.
The obtained temperatures are lower than those of a LEO, so to correctly design the optic train, it has been proven that further developments are needed, and the nominal state should be redesigned.Speaker: Daniel Navajas Ortega (Ansys)
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Welcome: Closure Newton
Newton
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ClosureSpeaker: Dr Harrie Rooijackers (ATG-Europe)
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