Mission Design for the CubeSat OUFTI-1

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CHAPTER 55.4 The launch windowThe launch window represents the time gap useful to place the satellite in apredetermined orbit from a specific launch site. As the orbital plane is fixed inthe inertial space, the exact launch instant is the time when the launch site onthe surface of the earth rotates through the orbital plane.The launch is possible only if the latitude of the launch site is smaller than theorbit inclination or equal to it: here comes the importance of having a spaceportas near as possible to the equatorial line.The time to launch depends on the right ascension of ascending node and onthe inclination required.In the OUFTI-1 case, as it will be secondary payload on the launcher, we cannotchoose any of these parameters and therefore we cannot determine the launchwindows.5.5 Earth coverageEarth coverage refers to the surface that a spacecraft instrument or antenna cansee at one instant or over an extended period. The leading parameters are thecovered area and the rate at which new land comes into view as the spacecraftmoves. We can so identify four key parameters:• Footprint Area also called instantaneous Field Of View area(FOV): areathat an instrument can see at any instant• Instantaneous Access Area (IAA): all the area that an instrument couldpotentially see at any instant if it were scanned through its normal rangeof orientations• Area Coverage Rate (ACR): the rate at which the instrument is sensingor accessing new land• Area Access Rate (AAR): the rate at which new land is coming into thespacecraft’s access areaFor an omnidirectional antenna, the footprint corresponds to the access area,as well the coverage rate to the access rate: for OUFTI-1 we need therefore tocalculate only two parameters.We consider a minimal elevation of the spacecraft over the horizon of ɛ = 5 ◦ andwe proceed to the determination of the field of view and of the area coveragerate. The notations are indicated in figure 5.25The first step is to find out the angle θ: for a directional antenna or anoptical payload it represents the beam width and is therefore imposed. In caseof omnidirectional antenna, the directivity diagram has an angle with a loss ofGalli Stefania 50 University of Liège
CHAPTER 5.MISSION ANALYSISFigure 5.25: Field of view (out of scale)3dB in gain much bigger than the earth angular radius: we can therefore assumethat all the earth is in the access zone of the antenna. In this case θ dependsfrom the fact that a point on the earth’s surface can see the satellite only if itis higher than 5 ◦ over the horizon.( )θ2 = asin Re sin (90 ◦ + ɛ)=R e + hOnce θ is known, λ can be calculated:{56.9 ◦ (1200Km)70.8 ◦ (350Km)(5.21)λ = 180 ◦ − θ 2 − (90 + ɛ) = {28.1 ◦ (1200Km)14.2 ◦ (350Km)(5.22)An approximated formula permits to calculate the footprint length, in thiscase we have the footprint radius:L F OV2= 111.319543 · λ ={3128Km (1200Km)1580Km (3500Km)(5.23)We would also like to know the footprint area, the area of the spherical cap:F OV area = 2πR 2 e (1 − sin (90 ◦ − λ)) ={3.0 · 10 7 Km 2 (1200Km)7.8 · 10 6 Km 2 (350Km)(5.24)Galli Stefania 51 University of Liège
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Page 7 and 8: CONTENTS1 Introduction 132 The LEOD
Page 9 and 10: LIST OF FIGURES4.1 A typical 1-unit
Page 11: LIST OF TABLES5.1 Comparison betwee
Page 15 and 16: CHAPTER2THE LEODIUM PROJECTThe LEOD
Page 17: CHAPTER3THE FLIGHT OPPORTUNITYThe E
Page 20 and 21: CHAPTER 44.1 The CubeSat conceptDur
Page 22 and 23: CHAPTER 4have to be smooth and thei
Page 25 and 26: CHAPTER5MISSION ANALYSISThe mission
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Page 31 and 32: CHAPTER 5.MISSION ANALYSISFigure 5.
Page 33 and 34: CHAPTER 5.MISSION ANALYSIS5.2 The o
Page 35 and 36: CHAPTER 5.MISSION ANALYSIS• the s
Page 37 and 38: CHAPTER 5.MISSION ANALYSISt − t 0
Page 39 and 40: CHAPTER 5.MISSION ANALYSISIn figure
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
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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
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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
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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 88 and 89: CHAPTER 99.3 Nodes modelThe CubeSat
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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CHAPTER 10.COMMUNICATION SYSTEM•
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CHAPTER 10.COMMUNICATION SYSTEMWe c
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CHAPTER11TESTSThe launch and space
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CHAPTER 11.TESTSof asking for some
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CHAPTER 11.TESTSThe random vibratio
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CHAPTER12FUTURE DEVELOPMENTSThe fea
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CHAPTER 12.FUTURE DEVELOPMENTSspace
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AcronymsAARACRACSADADCSASIAVUMBOLCC
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BIBLIOGRAPHY[1] Wiley J. Larson, Ja
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AcknowledgmentsI would like to than
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Mission Design for the CubeSat OUFTI-1

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