Mission Design for the CubeSat OUFTI-1

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CHAPTER 99.3 Nodes modelThe CubeSat configuration is still unknown and therefore a precise thermalstudy is impossible. The best thing to do in this case is to generate an equivalentnodes model in order to have a simplified representation of the structure to verifythe thermal exchanges with an equivalent electric model. Then the model ispassed to Thermal Excel. The fist step is indeed to identify a representationthat well symbolize the satellite: this corresponds to choose where to place thenodes. Then we need to identify the resistive connection between the nodesbased on the properties of the modeled part. In the next paragraphs this twosteps will be treated.9.3.1 RepresentationThe idea is to place a node for each part of the satellite and to study its thermalbehavior in the steady-state case: the model is shown in figure 9.1We assume that there is a face watching the earth and one directed to sun.Each face is represented by two nodes: the thermal coating and the solar cell (wehave two solar cells but they are modeled as one node). The solar cells are thenlinked to the back face structure through an equivalent conductive resistance.As the thermal coating thickness is really small, we consider it as a part ofthe structure: basically we use the conductive parameters of the real aluminumalloy material but the optics coefficient of the coating for the radiation. Thishypothesis is equivalent to impose that the coating and the back face structurehave the same temperature: as the thermal coating is just a painting, this isdefinitely verified in the reality. The node corresponding to the face structureis then connected to the other faces trough a conductive resistance.With reference to figure 9.1 we have the following convection:• nodes 1 → 6 are the solar cells• nodes 7 → 12 are the faces structures with thermal coating• node 99 is the cold space• node 98 is the earth• the black resistances represent conduction between solar cells and structure.They are based on solar cells properties• the blue resistances represent conduction between faces. They are basedon structure properties• the red resistances represent the infrared radiation between the faces andthe cold space. They are based on surface properties.Galli Stefania 88 University of Liège
CHAPTER 9.THERMAL-CONTROL SYSTEMFigure 9.1: Nodes model for thermal analysis• the green resistances represent the infrared radiation between the facewatching the earth and the earth.The sun light and the albedo are flux on the corresponding faces (node 2and 8 for the sun flux, nodes 5 and 11 for the albedo):Q sun = CsαSQ albedo = 0.3CsαS = 0.3Q sun(9.5)The factor 0.3 keeps into account the average reflectivity of the earth whereseas and continents have different values: in fact the albedo is the solar visibleflux reflected by the planet.9.3.2 Equivalent resistancesThe heat transfer between two parts of a body with different temperatures T 2and T 1 situated at distance L is ruled by the Fourier’s law:{ρc p∂T∂t⃗q = −k ⃗ ∇T= ⃗ ∇⃗q + σ(9.6)Galli Stefania 89 University of Liège
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Space is probably the main symbol o
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CONTENTS1 Introduction 132 The LEOD
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LIST OF FIGURES4.1 A typical 1-unit
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LIST OF TABLES5.1 Comparison betwee
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CHAPTER2THE LEODIUM PROJECTThe LEOD
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CHAPTER3THE FLIGHT OPPORTUNITYThe E
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CHAPTER 44.1 The CubeSat conceptDur
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CHAPTER 4have to be smooth and thei
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CHAPTER5MISSION ANALYSISThe mission
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CHAPTER 5.MISSION ANALYSIS5.1.1 Typ
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CHAPTER 5.MISSION ANALYSISIt can be
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CHAPTER 5.MISSION ANALYSISFigure 5.
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CHAPTER 5.MISSION ANALYSIS5.2 The o
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CHAPTER 5.MISSION ANALYSIS• the s
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Page 41 and 42: CHAPTER 5.MISSION ANALYSIS• if m
Page 43 and 44: CHAPTER 5.MISSION ANALYSIS5.3.3 The
Page 45 and 46: CHAPTER 5.MISSION ANALYSISwhere ϑ
Page 47 and 48: CHAPTER 5.MISSION ANALYSISFigure 5.
Page 49 and 50: CHAPTER 5.MISSION ANALYSISA four ye
Page 55: CHAPTER 5.MISSION ANALYSISFigure 5.
Page 58 and 59: CHAPTER 66.1 Pumpkin structureThe s
Page 60 and 61: CHAPTER 6Figure 6.2: ISIS structure
Page 62 and 63: CHAPTER 6Figure 6.3: P-POD: deploym
Page 64 and 65: CHAPTER 77.1 Inertia propertiesBefo
Page 66 and 67: CHAPTER 7I x = I x,cube + I x,M + I
Page 68 and 69: CHAPTER 7This rough estimation is e
Page 70 and 71: CHAPTER 7Otherwise, an orbit simula
Page 72 and 73: CHAPTER 7only slow down the rotatio
Page 74 and 75: CHAPTER 8order to prevent any failu
Page 76 and 77: CHAPTER 8We have now the vector ˆN
Page 78 and 79: CHAPTER 8Here we add an important h
Page 80 and 81: CHAPTER 8Figure 8.5: Total power pr
Page 82 and 83: CHAPTER 8Figure 8.8: Total power an
Page 84 and 85: CHAPTER 88.4 Battery and operating
Page 86 and 87: CHAPTER 99.1 Passive thermal-contro
Page 90 and 91: CHAPTER 9where c p is the material
Page 92 and 93: CHAPTER 9We have now all the parame
Page 94 and 95: CHAPTER 9A typical layout of a Ther
Page 97 and 98: CHAPTER10COMMUNICATION SYSTEMThe co
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Page 103 and 104: CHAPTER 10.COMMUNICATION SYSTEMWe c
Page 105 and 106: CHAPTER11TESTSThe launch and space
Page 107 and 108: CHAPTER 11.TESTSof asking for some
Page 109 and 110: CHAPTER 11.TESTSThe random vibratio
Page 111 and 112: CHAPTER12FUTURE DEVELOPMENTSThe fea
Page 113: CHAPTER 12.FUTURE DEVELOPMENTSspace
Page 117 and 118: AcronymsAARACRACSADADCSASIAVUMBOLCC
Page 119 and 120: BIBLIOGRAPHY[1] Wiley J. Larson, Ja
Page 121: AcknowledgmentsI would like to than
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Mission Design for the CubeSat OUFTI-1

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