Mission Design for the CubeSat OUFTI-1
Mission Design for the CubeSat OUFTI-1 Mission Design for the CubeSat OUFTI-1
CHAPTER 1111.3 Environmental testsThe space environment is extremely hostile for a satellite: radiations, thermalcycling and vacuum are the main problems. Especially the electronic equipmentare sensible as they have narrow temperature limits and often suffer of damagesdue to radiations.Given that all the material used on OUFTI-1 will be among the approved materialof NASA in order to avoid an excessive out-gassing, the behavior of thespacecraft and of the payload need to be carefully tested. Environmental testinclude thermal vacuum, thermal cycling and other more mission oriented testsas rain and humidity test.For OUFTI-1 thermal-vacuum and thermal cycling are combined with a thermalbalance test in a single vacuum sequence.The thermal vacuum test level for acceptance test are indicated in table11.1. The duration of the acceptance test to use for the PFM test is 2 hours.Table 11.1: Thermal vacuum qualification test for the PFM.Number of cycles 4Maximum Temperature T max70 ◦ CMinimum Temperature T min20 ◦ CDuration at T max2hDuration at T min2hTemperature rate (heating) < 20 ◦ C/min (internal),> 20 ◦ C/min (external)Temperature rate (cooling)2 ÷ 3 ◦ C/minThe thermal cycling level for acceptance are indicated in table 11.2. Theduration of the acceptance test to use for the PFM test is 2 hours.Table 11.2: Thermal cycling qualification testNumber of cycles 10Maximum Temperature T max70 ◦ CMinimum Temperature T min20 ◦ CDuration at T max2hDuration at T min2hTemperature rate (heating) < 20 ◦ C/min (internal),> 20 ◦ C/min (external)Temperature rate (cooling)2 ÷ 3 ◦ C/minStabilization criterion1 ◦ C/1hGalli Stefania 110 University of Liège
CHAPTER12FUTURE DEVELOPMENTSThe feasibility study of a satellite is only the first step of the design of a spacemission: starting from it, a detailed study needs to be performed.If the structure’s CAD model is already available as we are using an off-the-shelfstructure, the location and the number of the electronic boards and of the payloadhas not been decided yet. Once it will be known, a detailed modal studycan be carried out in order to identify the eigenmodes and the eigenfrquenciesand to verify with a finite elements analysis the resistance to the flight loads.The antennas deployment system design represents another challenging task:they will be in fact wrapped around contact points and maintained in thisconfiguration using the deployment mechanism. Their foreseen position in themiddle of the faces between the two solar cells needs still to be verified: this isin fact the best solution on the communication point of view but not necessaryon the mechanical and energetic ones. Furthermore, if their position won’t bealigned with the gravity center, additional attitude problems can appear duringdeployment: in fact, unless opposite antennas are deployed simultaneously, atorque would be generated.A decision about the attitude control has also to be taken as soon as possiblein order to begin the design of the control system or to foreseen a satellite tumblingin space.The thermal design based on the complete model has also to be detailed inorder to choose between black and golden painting or to plan a combination ofthe two.The electric and electronic hardware as well as the solar cell type must be fixed:only with a precise estimation of efficiencies and losses, we will know the exactpower available.111
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CHAPTER12FUTURE DEVELOPMENTSThe feasibility study of a satellite is only <strong>the</strong> first step of <strong>the</strong> design of a spacemission: starting from it, a detailed study needs to be per<strong>for</strong>med.If <strong>the</strong> structure’s CAD model is already available as we are using an off-<strong>the</strong>-shelfstructure, <strong>the</strong> location and <strong>the</strong> number of <strong>the</strong> electronic boards and of <strong>the</strong> payloadhas not been decided yet. Once it will be known, a detailed modal studycan be carried out in order to identify <strong>the</strong> eigenmodes and <strong>the</strong> eigenfrquenciesand to verify with a finite elements analysis <strong>the</strong> resistance to <strong>the</strong> flight loads.The antennas deployment system design represents ano<strong>the</strong>r challenging task:<strong>the</strong>y will be in fact wrapped around contact points and maintained in thisconfiguration using <strong>the</strong> deployment mechanism. Their <strong>for</strong>eseen position in <strong>the</strong>middle of <strong>the</strong> faces between <strong>the</strong> two solar cells needs still to be verified: this isin fact <strong>the</strong> best solution on <strong>the</strong> communication point of view but not necessaryon <strong>the</strong> mechanical and energetic ones. Fur<strong>the</strong>rmore, if <strong>the</strong>ir position won’t bealigned with <strong>the</strong> gravity center, additional attitude problems can appear duringdeployment: in fact, unless opposite antennas are deployed simultaneously, atorque would be generated.A decision about <strong>the</strong> attitude control has also to be taken as soon as possiblein order to begin <strong>the</strong> design of <strong>the</strong> control system or to <strong>for</strong>eseen a satellite tumblingin space.The <strong>the</strong>rmal design based on <strong>the</strong> complete model has also to be detailed inorder to choose between black and golden painting or to plan a combination of<strong>the</strong> two.The electric and electronic hardware as well as <strong>the</strong> solar cell type must be fixed:only with a precise estimation of efficiencies and losses, we will know <strong>the</strong> exactpower available.111
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