Mission Design for the CubeSat OUFTI-1

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CHAPTER 7Otherwise, an orbit simulation with the updated satellite attitude has beenrun: the results are shown in figures 7.4 and 7.5.Figure 7.4: Gravity gradient couple for one orbit in case of updated configurationFigure 7.5: Gravity gradient couple for one orbit in case of updated configurationGalli Stefania 70 University of Liège
CHAPTER 7.ATTITUDE CONTROL SYSTEMWe can see that the couples trend in the updated case is almost the samethan in the non-updated.7.3 Attitude control hardwareThe main question in the OUFTI-1 project is if we really need an attitudecontrol system. In fact, the use of omnidirectional antennas doesn’t require aspecific orientation of the satellite respect to the earth. In theory, there wouldbe only one position to be avoided: the ideal antennas gain diagram shows infact that the only case that prevents the communication is when the antenna ispointing directly to the ground station. In the real world, as the presence of theCubeSat structure between the antennas avoids the perfect dipole, the gain isnon-null even along the antennas direction. Anyway it will be really small andprobably not enough to guarantee the communication. In this case we wouldlike to avoid these undesired positions.Another problem connected to the attitude control system is that the rotationrate of the satellite shouldn’t be too high. In fact, an high rotation ratecombined with the satellite speed on the orbit, could generate an huge speedrespect to the ground station with the consequent doppler effect. Event if it canbe corrected on earth, we cannot accept a too high value to guarantee a goodcorrection. Zero angular velocity is also undesired because of the risk of havingthe antennas pointing towards the earth and because of thermal behavior witha side continuously in sunlight.Excluded all the active ACS devices as inertia and momentum wheels becausethey require a power that is not available and because basically we do not needto control the satellite but only to avoid some angular positions, we have twopossible choices: leave out any attitude control system or choose a passive system.The KISS philosophy would push us towards the first one but the need ofa good communications level makes us think it out.A possible ACS would be a Passive Magnetic Attitude Control System (PMACS).It has been used before on other CubeSats as Delfi-C3 and in XI-IV, respectivelyat the University of Delft (The Netherlands) and at the University ofTokio (Japan).Generally, it consists of a strong permanent magnet and hysteresis material onone or two axes to damp rotation. The only rotation left is therefore the oneabout the longitudinal axis of the magnet and the hysteresis material dampthe rotations about the others. As the magnet would align itself with the earthmagnetic field (almost always parallel to the earth surface on the OUFTI-1 orbitas the inclination is low), we could in this case place the magnet on a directionthat prevents the antennas to be pointed towards the earth.Otherwise, we could use only hysteresis material on all the three axes: in thiscase, they wouldn’t try to align themself to a precise direction but they wouldGalli Stefania 71 University of Liège
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Space is probably the main symbol o
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CONTENTS1 Introduction 132 The LEOD
Page 9 and 10:
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
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
Page 27 and 28: CHAPTER 5.MISSION ANALYSIS5.1.1 Typ
Page 29 and 30: CHAPTER 5.MISSION ANALYSISIt can be
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
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 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 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
Page 99 and 100: CHAPTER 10.COMMUNICATION SYSTEMstre
Page 101 and 102: CHAPTER 10.COMMUNICATION SYSTEM•
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
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AcknowledgmentsI would like to than
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Mission Design for the CubeSat OUFTI-1

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