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2 ISSUE : 02 Page : 2/30 CHANGE RECORDS ISSUE DATE CHANGE RECORDS AUTHOR Nov-08 1st ISSUE V. PEROTTO 02 Issue dedicated to 2016 mission only V. PEROTTO General update to take into account new 2016 missions items, as Science P/L. The Rover and all what related to 2018 mission have been removed. CRSM replaced by an Orbiter DM replaced by EDM (EDL Demonstrator Module) used for 2016 mission General update to take into account presence of Instrument Payloads on Orbiter Added requirements for Reduced models (chapter 10)

3 ISSUE : 02 Page : 3/30 TABLE OF CONTENTS 1. INTRODUCTION DOCUMENTS ESA Documents Thales Alenia Space Italia Documents Other documents ACRONYMS AND ABBREVIATIONS DEFINITIONS OF SUBASSEMBLIES, INTERFACES AND NODAL BREAKDOWN NODE NUMBERS AND NODE IDENTIFICATION Maximum number of nodes in GMM and TMM TMM node numbers TMM node labels MODELLING RULES GMM and TMM Submodelling Model hierarchy Units Reference frames Orbiter Module Coordinate Frame Composite Coordinate Frame EDM Coordinate Frame Unit Reference Frame Time origin on Mars Number of positions for solar fluxes calculation on Mars Power dissipations terminology Modelling of absorbed solar direct power on Mars Modelling of absorbed scattered solar power on Mars Dust modelling and optical properties change...16

4 ISSUE : 02 Page : 4/ Air properties on Mars Modelling of convection with external air Modelling of conduction and convection with internal air Sky radiative temperature Ground model Simulation type Energy balance output Temperature output Models description Models delivery format Models files contained information SOFTWARE TOOLS MODELS DELIVERY SUMMARY OF DATA NEEDED FOR MODELLIZATION CORRELATION RULES FOR REDUCED MODELS APPENDIX A - IDENTIFICATION OF TRUE ANOMALIES AND TIME SHIFT APPENDIX B - CO2 PROPERTIES AND CONVECTION SIMULATION APPENDIX C - MARS GROUND MODEL APPENDIX D - CALCULATION OF ENERGY BALANCE AND OUTPUT...29

5 ISSUE : 02 Page : 5/30 LIST OF FIGURES FIGURE 1-1 : COMPOSITE CONFIGURATION... 6 FIGURE 6-1 : MODEL TREE FIGURE 6-2 : SCHEME OF CONDUCTORS FOR AIR INSIDE CAVITIES LIST OF TABLES TABLE 9-1 : SUMMARY OF DATA NEEDED FOR MODELIZATION... 23

6 ISSUE : 02 Page : 6/30 1. INTRODUCTION The ExoMars Spacecraft Composite, including the EDM will be launched in January 2016; the Rover module will be separately launched in 2018 and has been deleted from this document. Components for 2016 mission: ESA provides S/C composite made up of: Entry Descent & Landing Demonstrator Module (EDM) Orbiter Bus Main Separation Assembly (MSA) Figure 1-1 : Composite configuration The Orbiter Module (OM) is the element that carries the EDM from Earth to its entry interface point to Mars. The EDM is the element that performs the Entry Descent and Landing (EDL) onto the Martian surface. From the thermal point of view the 2016 mission presents the following main phases: 1. The flight from Earth orbit to Mars orbit, with an increase of the distance from sun and reduction of the solar constant, and small internal dissipations except during check-outs. The thermal design must cope with generally cold conditions, allowing for temporary heating during check-outs and manouvres.

7 ISSUE : 02 Page : 7/30 2. The EDM entrance and deceleration in Mars athmosphere with aerothermal heating, followed by descent in cold athmosphere, and finally soft landing of the SSP. The thermal design must protect from aerothermal fluxes and the subsequent cold transient. 3. The 8 days on Mars surface of the EDM, without any solar arrays or RHU 4. The about 2 years of Science mission of the OM at about 400 Km 5. The Data Relay phase in Low Mars Orbit of the OM The thermal design of Exomars modules and their components will be achieved by extensive use of simulations with geometrical and thermal mathematical models (GMM and TMM). They will range from small models of experiments, whose environment is the internal of a module and/or the Mars environment, to models of a complete module as the EDM whose design driver is Mars environment. In other terms several levels of models are needed, from low level component to high level module and overall spacecraft composite. The players of TMMs are: Contractors responsible for the design of parts of the EXOMARS modules, for example the scientific experiments, they will deliver their TMM to module responsibles for checks and simulations at module level. TAS-F as responsible of the thermal design of the OM, it will also integrate models of contractors and it will deliver its TMM to system responsible. TAS-I as EXOMARS system responsible. It will make TMM of EDM and MSA and will generate and maintain the Overall Exomars TMM. Several needs arise: 1. To provide proper environmental conditions to the responsibles of low level experiments and components TMM, using also the specific ESA tool (LMD tool) to derive Mars environment as a function of season, landing site, day etc. 2. To guarantee coherence of the modelling techniques and assumptions to simulate the heat transfer and Mars environment. 3. To standardize outputs of thermal parameters (temperatures and energy balances are the most important) for easy interpretation and transfer of results. 4. To ensure a smooth integration of TMM into higher level TMM. Scope of this document is: 1. to present the requirements to be followed by all TMM responsibles for the thermal modelling and simulations, in particular: Hierarchy of models and requirements for their easy integration. Techniques for modelling of specific heat transfer modes and environmental conditions. Rules for output generation and verification of results. Examples of models. 2. To provide all the data and the models required by TMM responsibles for their analysis. Note: All requirements presented in this document refer to both Detailed and Reduced models that the TMM responsible may need.. The use of the LMD tool is not trivial, and will be maintained by TAS-I. They will generate the Mars environment conditions for all other TMM responsibles.

8 ISSUE : 02 Page : 8/30 2. DOCUMENTS 2.1 ESA Documents [NR01] Mission and System Requirements Document, EXM-MS-RS-ESA-0001, Issue 6, rev.0, 15 Feb [NR037] ECSS-E-ST-31C Space Engineering - Thermal control general requirements, 15 November Thales Alenia Space Italia Documents [NR0100] Exomars Spacecraft Composite Requirements Specification, EXM-MS-SYS-AI-0001, Issue 8, 29 June [NR0121] [NR0167] List of NR/IR documents, acronyms and abbreviations, EXM-MS-LIS-AI-0001, Issue 6, 26 Nov Thermal Environment and Test Requirements Specification, EXM-MS-SSR-AI-0013 Issue 2, 20 Nov Other documents N/A

9 ISSUE : 02 Page : 9/30 3. ACRONYMS AND ABBREVIATIONS See document EXM-MS-LIS-AI-0001 [NR0121]

10 ISSUE : 02 Page : 10/30 4. DEFINITIONS OF SUBASSEMBLIES, INTERFACES AND NODAL BREAKDOWN Mathematical models shall be generated for the following subassemblies: OM EDM ESP MSA Mars ground P/L on board ESP : Sensor Temperature sensors Pressure sensor Humidity sensors Laser Anemometer and Dust Analyzer Optical Depth Sensor Mars Oxidant Instrument UV Photometer Camera System Optical Retro reflector Brief Description Atmospheric temperature Atmospheric pressure Atmospheric humidity Wind velocity, dust deposition and charging Atmospheric opacity Oxidizing effects of atmosphere, sunlight and dust UV transmission of the atmosphere Wide Angle Cameras Corner Cubes in mounting assembly 6 P/L on board OM: o SFTIR= Solar Fourier Transform IR Spectrometer; Broad survey of trace gases with high precision o SLNIR= Solar-Nadir IR Mapper; Detection and mapping of specific trace gases o Sub-mm = Sub-mm Spectrometer profiler/mapper; Atmospheric temperature & winds plus H2O and specific trace gases o TIR = Thermal IR profiler/mapper spectrometer or radiometer for atmospheric temperature and dust, plus H2O and some trace gases o WAC = Wide Angle Camera imaging; atmospheric phenomena for discriminating between surface, dust clouds & ice clouds o HRCSC = High Resolution Colour Stereo Camera; Surface imaging

11 ISSUE : 02 Page : 11/30 5. NODE NUMBERS AND NODE IDENTIFICATION 5.1 Maximum number of nodes in GMM and TMM Maximum number of TMM nodes and GMM shells in any model of an EXOMARS Module including its sub models shall be: OM : 1000 (without P/L) OM P/L : 200 each P/L MSA : 100 EDM : 1000 (without P/L) EDM P/L : 30 each P/L Mars ground : 1000 In case the detailed models would exceed the max acceptable quantity of nodes above listed (this could for example be applicable to the Orbiter), a reduced model shall be provided. The reduced model shall be correlated to the detailed one according to the rules reported in para TMM node numbers All node number shall have at least 6 digits WXYZZZ. W shall indicate the module or main part of module. Digits shall be: Space CO2 on Mars Inactive node (if any) OM : 1XYZZZ to o OM experiments : 191ZZZ to SFTIR : 192ZZZ to SLNIT : 193ZZZ to TIR : 194ZZZ to WAC : 195ZZZ to HRCSC : 196ZZZ to EDM : o 2 XYZZZ Back Shield BSH to o 3 XYZZZ Front Shield FS to o 4 XYZZZ Lander to , in particular Lander experiments 49YZZZ to MSA : from 5XYZZZ t Mars Ground : from 900NMMPP (where N in depth from surface, M along radius, P along circumference)

12 ISSUE : 02 Page : 12/ TMM node labels 1. Node labels shall not exceed 24 characters. 2. Node labels shall not include blank spaces (Hint: use _ instead of blank space).

13 ISSUE : 02 Page : 13/30 6. MODELLING RULES 6.1 GMM and TMM Submodelling Any model with the exception of the Overall EXOMARS MODEL shall be prepared for incorporation in another higher level model. To achieve this, it is necessary to start from the GMM, by specifying for each shell side the submodel it belongs. Submodelling in GMM shall be implemented by specifying in each shell the arguments model1 and model2. If the values given to the arguments are different (i.e. the two faces belong to different submodels), which of them is used in calculations shall be defined using side1 or side2 as ACTIVE or INACTIVE. 6.2 Model hierarchy Figure 6-1 : Model tree

14 ISSUE : 02 Page : 14/30 This scheme shall be followed for GMM and TMM. Each company in the models architecture scheme shall be responsible for: Delivery of inputs, including this document, to responsibles of submodels Verification of submodels including compliance to this document Collection/verification/integration of submodels. Delivery of its model to higher level 6.3 Units All drawings, specification, measurement and engineering data including GMM and TMM shall only use the International System of Units (IS units). In particular all dimension used shall be in meters [m]. Linear conductive couplings in Watts per Kelvin [W/K]. Mass in Kilogram s [kg] Celsius temperatures in [ C] Heat inputs in Watts [W] Time in seconds [s] Thermal capacity in Joules per Kelvin [J/K] Radiative couplings in [m2] 6.4 Reference frames The following right hand orthogonal reference frames shall be used for the GMMs Orbiter Module Coordinate Frame The Carrier Module shall use the following reference system: X axis: central tube axis Z axis: rotation axis of Solar Arrays Y axis: to complete the reference system (-Y is Nadir pointing) Composite Coordinate Frame The composite Reference Frame shall be the Orbiter Reference Frame EDM Coordinate Frame The Descent Module Coordinate Frame (EDM) is a right-handed, orthogonal coordinate system defined as follows: The BSH cone vertex is the centre of the EDM reference frame. The +X axis emanates from this point towards the FS. The [YZ] plane is perpendicular to the X direction. The Y direction is sun pointing in Cruise.

15 ISSUE : 02 Page : 15/ Unit Reference Frame The Unit Coordinate Frame (UN) is a right-handed, orthogonal coordinate system, fixed to the unit geometry, and defined as follows: one of the attachment holes of the unit shall be chosen as the Reference Hole which shall be identified by an engraved letter "R" on the unit the O-UN origin shall be located at the centre of the Reference Hole at the level of the mounting interface plane the X-UN axis shall be perpendicular to the mounting interface plane, pointing positively towards the unit the Y-UN- and Z-UN axes shall be oriented such that the unit will be included inside the +Y/+Z quadrant of the mounting interface plane. Moreover, if the unit has a rectangular shape, the +Y and +Z axes shall be parallel to the sides of the unit Inertial Reference Frame. Note: UN is an acronym staying for the name of the unit itself (e.g. STR = Star Tracker) 6.5 Time origin on Mars Time origin shall be local midnight. 6.6 Number of positions for solar fluxes calculation on Mars Number of positions for GMM calculation of solar fluxes in one sol must be minimum 25, first and last correspond to time origin. Note: GMM requires as input the initial and final true anomalies. Appendix A describes a method (use is not mandatory) to identify them from required Ls, and how to calculate and apply a time shift to results in order to have the time origin as required at midnight. 6.7 Power dissipations terminology The following terminology shall be used for powers: QA = on orbit: albedo; on Mars: not used QE = on orbit: planetary infrared; on Mars: solar scattered QS = on orbit: solar direct; on Mars: solar direct with attenuation QI = equipment dissipation, including RHU QR = heater dissipation (including LHP control)

16 ISSUE : 02 Page : 16/ Modelling of absorbed solar direct power on Mars Solar direct power absorbed by external surfaces shall be calculated by GMM and corrected in TMM model to account for attenuation in atmosphere, as: QSnode = QSnode_from_GMM * Solar_attenuation [W]. Solar attenuation shall be calculated from LMD tool as: Solar_attenuation = solar direct power on Mars horizontal surface from LMD tool / solar direct power on Mars horizontal surface from GMM Solar direct power for LMD tool shall be calculated as difference between total incident power and scattered incident power. For calculation of attenuation factor all nodes of Mars ground shall be used. 6.9 Modelling of absorbed scattered solar power on Mars Modelling of solar scattered power absorbed by external surfaces shall be calculated in TMM as follows, using variable QSI: QEnode =[ GR(node, space) / epsilon_node ) ] * alpha_node * Incident_scattered_flux [W] Where: GR(node, space) shall be calculated with GMM and does not include Boltzmann constant, being in [m2] Incident_scattered_flux [W/m2] from LDM tool 6.10 Dust modelling and optical properties change Dust accumulation shall be simulated, by assuming that: 1. Horizontal surface optical properties change due to deposition from original values to solar absorptance 0.9 and infrared emittance 0.8; 2. Vertical surfaces optical properties are not altered by dust Air properties on Mars MARS atmosphere is > 90% CO2, the properties of CO2 reported in Appendix B shall be used.

17 ISSUE : 02 Page : 17/ Modelling of convection with external air Convection with external air shall be modelled in TMM as: GL(node, external_air) = h * Area_node Where h [W/m2/K] is calculated from literature for Mars conditions, Appendix B contains an ESATAN subroutine for this purpose (use is not mandatory): Wind speed shall be defined as a constant, with values between 0 and 20 m/s, h shall be calculated from literature for forced convection.. Wind speed =0 shall correspond to free convection. In this case h shall be calculated from literature for free convection. A flag shall be used to set Nusselt =1 if required by user Modelling of conduction and convection with internal air Conduction with air contained in enclosures, where air exchange with external environment is negligible, shall be modelled by introducing in each enclosure an air node, coupled by GL with all the surfaces in contact with air, as follows: GL (node, internal_air) = h * Area Where h [W/m2/K] is calculated from literature for Mars conditions. Appendix B contains an ESATAN subroutine for this purpose (use is not mandatory): Note1 Equipments and experiments normally are shaped as boxes of various shapes with internal cavities. The internal air shall be simulated in the analysis made by experiment / equipment responsible. Note2: In small enclosures (typical distance between two walls maximum 30 mm) it is possible to assume only conduction (assumption to be approved by system), i.e. Nusselt = 1 and GL(node, internal_air) = Kco2 * Area_node / ( L / 2) Where: Kco2 is the conductivity [W/m/K] of Co2 versus temperature as per Appendix B L [m] is a characteristic distance between the surfaces (see example below) Area [m2] is the area of the node surface in contact with air Example: GL1 is from unit to air (one GL per unit, with unit total area, distance L is the average distance box - walls)

18 ISSUE : 02 Page : 18/30 GL2 is from air to enclosure walls (as many GL as the number of wall nodes, with walls area, distance L is half the local distance box individual wall) Units, GL1 GL2 Figure 6-2 : Scheme of conductors for air inside cavities 6.14 Sky radiative temperature Sky or space shall be modelled as a boundary node with the temperature calculated with LMD tool Ground model Ground shall be modelled as follows: The ground is affected by the presence of EDM; therefore it is modelled with several layers of nodes, each of increasing thickness from surface to depth of TBD [m]. The deepest nodes are maintained as boundaries with temperature from LMD tool. All other nodes are diffusive; they have only initial temperatures from LMD tool for that landing site. Two groups of nodes shall be used: 1. A fine mesh under / near the EDM, they are called landing site 2. A coarse mesh farther from the EDM, they are called landing area

19 ISSUE : 02 Page : 19/30 Horizon is also simulated, for an elevation maximum 10 deg versus horizontal Slope of Mars ground landing site shall be accounted for: maximum slope is 25 deg (TBC), Worst cold cases shall assume slope that minimizes solar input, worst hot cases with slope that maximizes solar input. Horizon shall be modelled in hot cases only. The model of the ground shall be provided by TAS-I. It is described in Appendix C Simulation type 1. All simulations o Mars shall be transients for multiples of the day period (average value in Martian year [s]). 2. Number of days shall be identified to guarantee stabilization of daily energy balance within 5% Energy balance output Energy balance shall be calculated for a day period, accounting for each heat path and energy source, and presented as an Excel table of energy input/outputs versus time. See Appendix D as example Temperature output Temperature output shall be provided as an Excel table of temperature versus time See Appendix D as example Models description Models shall be described in a dedicated document XXX thermal and geometrical model description, where XXX is the name of module, experiment etc. Content of the document shall be as per NR[037]. This document shall be updated before each analysis campaign or after major design changes, to be agreed on a case by case basis.

20 ISSUE : 02 Page : 20/ Models delivery format Models shall be delivered as ASCII files, as attachments of Model description document. Updates of the models may not need new issue of model description document, to be agreed on a case by case basis Models files contained information Instructions on how to interpret and run the TMM and GMM files shall be contained in the model files at the beginning of the files. Instructions on how to interpret specific modelling solutions shall be written in the blocks of GMM and TMM where the correspondent code lines are written. All constants and arrays shall be described where first defined.

21 ISSUE : 02 Page : 21/30 7. SOFTWARE TOOLS The thermal analysis shall use the following software: 1. ESARAD version 6.2 or following shall be used for radiative simulations with GMM 2. ESATAN version 10.2 or following shall be used for thermal simulations with TMM

22 ISSUE : 02 Page : 22/30 8. MODELS DELIVERY The models shall be described in a Thermal and geometrical model description report This report shall be written according to NR[037], that specifies the content and the structure of this type of document. TMM and GMM shall be delivered together with the definition and results of representative test cases.

23 ISSUE : 02 Page : 23/30 9. SUMMARY OF DATA NEEDED FOR MODELLIZATION The following table summarized the data needed for modelling, they are partly in Appendices of the present documents and part in separate files: Data Content Notes 1 Calculation of true anomalies 2 Convection calculation subroutine and CO2 properties 3 Mars ground model 4 Calculation of energy balance and outputs File EXCEL Mars_orbit_mechanic_small.xls File convection.txt Files MARS_GROUND.GMM, MARS_GROUND.TMM, EXOM61.erg, MARS_LS40 File energy.doc See Appendix A See Appendix B See Appendix C See Appendix D Table 9-1 : Summary of data needed for modelization

24 ISSUE : 02 Page : 24/ CORRELATION RULES FOR REDUCED MODELS The responsibles of the modules and experiments may need to develop for their design purposes some detailed models (DGMM and DTMM) that do not fit with the node limits set in this document. In this case they shall deliver the detailed models generate from the detailed models some reduced model (RGMM and RTMM), that shall be correlated versus the detailed models All requirements presented in this document refer to both DTMM and RTMM. As a minimum three reference thermal cases shall be used to correlate the RTMM: one cold thermal case one hot thermal case one thermal transient case The following output files generated by each model case, to check correct running, shall be delivered: Output file containing for each node the results of steady state runs. One line per node with label, temperature calculated, applied heat input, capacitance. Output file containing for each node minimum and maximum temperature reached during transient run, and the corresponding times. Criteria for successful REDUCED model correlation The RTMM shall be correlated with the Detailed TMM by comparing the results of analyses. The results of the correlation shall be shown in the delivered documentation. The reduced TMM shall correlate with the DTMM within the following limits: Same boundary nodes as in the detailed model Dissipation: Total internal dissipation equal between RTMM and DTMM Temperature criteria: Average temperature of all internal units : < 2 C Average temperature of all internal structures and units : < 3 C Temperature of internal unit baseplate (TRP) : < 4 C Temperature of external unit baseplate (TRP) : < 6 C Temperature of structure and radiator nodes : < 8 C External MLI (average on each main side) : < 15 C Heat flux criteria: Interface heat flux from baseplate to radiator panels: <10% Heater criteria (per heater line) Required heater power: <10% Difference of heater power between DTMM and RTMM: <10%

25 ISSUE : 02 Page : 25/ APPENDIX A - IDENTIFICATION OF TRUE ANOMALIES AND TIME SHIFT Calculation of true anomalies necessary to simulate a specific Ls can be made with the EXCEL file: Mars_orbit.xls. Enter field in green and pick results of initial and final true anomalies to be used with ESARAD For mode precise calculations it is necessary to use the duration of day for the selected sol. It can be found with the simplified model of Mars.

26 ISSUE : 02 Page : 26/ APPENDIX B - CO2 PROPERTIES AND CONVECTION SIMULATION See file convection.doc, it contains an ESATAN model with routines and arrays to calculate CO2 properties and convection. Explanations are in the file.

27 ISSUE : 02 Page : 27/ APPENDIX C - MARS GROUND MODEL Mars ground model is provided in filed MARS-GROUND.GMM and MARS_GROUND.TMM, EXOM61.erg, MARS_LS40, Such files are automatically generated with a specific program, to be able to modify the model as necessary, in case of need the model can be regenerated. The generated model is then used by a higher level model in file exom_prova_cone.erg that also sets the latitude, the orientation of the surface where the EDM sits, i.e its tilt and angle versus the meridian. A kernel file is given that may be included as follows: a) Process geometry files b) Go into Radiative Case menu c) File Include pick kernel file (automatic calculation of GR and fluxes should start) d) You should be able to visualize planet and the landing site, and also check results of fluxes calculations, in order to calculate time shift. Lander Airbag Landing_site Landing_area

28 ISSUE : 02 Page : 28/30 Simple model used for checks: Iplanet = 1 Icomplex = 0 Complex model Iplanet=1 Icomplex =1

29 ISSUE : 02 Page : 29/ APPENDIX D - CALCULATION OF ENERGY BALANCE AND OUTPUT Instructions and example on how to calculate with TMM the energy balance are given in file energy.doc

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