1. Thermal Control Subsystem
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2. Space Thermal Environment
Qs : Direct radiation from the Sun
Qe : Radiation from the Earth
Qa : Solar radiation reflected back by the earth (Albedo)
Qi : Heat generation
Qps : Radiation to Space
Qpe : Radiation to the Earth Qa
Qps Qs
Qpe Qe Qi
Earth pic:
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3. Orbit Model Approximated ISS Circular orbit: Atitude (H) :
Period (T) :
Shadow angle ( ) :
Shadow time (Ts) :
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4. Orbit Model o
Shadow
Sunlight
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5. 1. Steady-State Approximation
Assumptions:
Steady State: dT/dt=0
Spherical satellite with thermal surface area A= 2.16m^2 so An=0.54m^2
Surface characteristic:
Heat generration: 50W
View Factors:
6) Direct Solar flux: 0 (Cold), 1399w/m^s (Hot)
Results:
Worst-case HOT: Tmax= K
Worst-case COLD: Tmin = K
Tmax-Tmin=96.7 K
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6. 2. Node Analysis Thermal Equilibrium Equation Qs Qe Qa Qps Qpe
Conduction between Node i and Node j
Radiation between Node i and Node j
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7. Satellite Model for Node Analysis
Surface 2 always look downward.
Assume no width for each surface
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8. Ex: Direct Solar Flux (Worst-case Hot)
0.616
0.788
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9. Worst Cases Worst-case Cold Worst-case Hot FF THERMAL CONTROL
Earth pic:

10. Surface characteristics
Inside of the satellite is painted with L-300 (Black)
Conductivity between surfaces : K=0.06
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11. Simulink model (Node Analysis)
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12. Simulation (Worst-case COLD)
Temperatures [K]
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13. Simulation (Worst-case HOT)
Temperatures [K]
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14. Results (Node Analysis)
High temperature differences on surface 4 and 5
Use MLI to make thermal disturbances from outside smaller.
Need to consider thermal control methods to make temperature higher.
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15. Future works
Thermal Control by using Thermal Control Elements so that Design Temperature range fits Permissible temperature range of components.
More-nodes analysis for accurate simulation
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