Sat Tech: Thermal Control Flashcards

1
Q

Thermal Conditions in Space (3):

A
  • Environment: Sun, Albedo & Atmos. Radiation, etc.
  • Internal: Electronics, RTG & Batt., Propulsion sys.
  • Maneuvers: Air-breaking, reentry.
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2
Q

Reasons why a thermal assessment is important (4):

A
  • Electronics, mechanical components, propellant, etc. only operate well in a certain temperature range.
  • Propellants require a well-defined temperature window.

• Extreme temperature gradients or large temperature fluctuations in a very short time cause thermal
distortion of components
– Structural damage

• Internal systems are heat sources and require heat dissipation.

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3
Q

Heat Sources: External (3)

A

1) Sun: Radiates all bodies in Solar System
2) Planets: Albedo (reflecting radiation from the sun)
3) Planetary IR Radiation

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4
Q

Heat Sources: Internal (3)

A

1) Propulsion System
2) Heaters: for propellant tanks heat
3) Electric Systems: creates resistance producing heat dissipation

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5
Q

Thermal Control Methods (3)

A
  1. Operation: choice of orbit or s/c alignment with external heat sources (Sun etc.)
  2. Surface properties: every object emits and absorbs energy in the form of IR radiation.
  3. Others: Use of heaters, heat pipes, radiators, shutters etc.
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6
Q

Thermal Control: Passive Methods (4)

A

1.- Material Choice:
• Material with preferable α/ε ratio to regulate equilibrium temperature

2.- Shadow:
• Use of (black) structures to block sunlight

3.- Multi-Layer Insulation:
• Reduces the heat loses by thermal radiation
• No thermal contact between layers

4.- Heat Pipes:
• Working fluid evaporates to vapour absorbing thermal energy

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7
Q

Thermal Control: Active Methods (3)

A
    • Reflector mirrors & cooling down with helium
    • Radiators: Heat transfer via conduction
    • Shutters and Louvres: Mechanism to control the amount of incident energy
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