Spacecraft Thermal Management

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Spacecraft Thermal Management

• Lecture 20
• Space concepts

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Space news

• Falcon 1 rocket lifts of and goes into space, but
  not orbit
• 1/5 the cost of previous lauchers
• Standard lox kerosene turbo pump design

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Agenda

• The Blackbody Radiation Curve
• Thermal Radiation in Space
• The Cosmic Background
• Thermal Radiation in Space
• Thermal radiation equilibrium
• Thermal Conduction
• Spacecraft Thermal Management

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Why do the stars shine?
Because they are hot! Including the Sun!
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Blackbody Radiation Curve
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Blackbody Radiation Curve
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Black Body Radiation Curve
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Blackbody radiation

• If a body absorbs and radiates EM radiation
  perfectly, it is called a blackbody
• It then radiates power by the Stefan Boltzman Law
  W/m2 ??T4
• ?emissivity, 1 for a black body , ? gt1 for real
  surfaces
• ?5.76x 10 8 Wm 2 K-4
• ( Stefan-Boltzmann constant)

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Cosmic Background Radiation
Temperature of space is TCosmos2.72K (cold) (
This is why it is dark at night)
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Space Thermal Radiation problems

• Spacecraft receive and radiate heat by blackbody
  radiation
• They receive radiation because the sun is hotter
  than they are ( 10,000K)
• They can dump heat to space because it is colder
  than they are (2.7K)
• These two phenomenon are tools for engineers

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Kirkhoffs Law

• Energy Conservation Poyntings therom

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Emission and Absorption
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Solar Spectrum
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Radiant equilbrium
Radio Transmissions
Planetary radiance
Sunlight
Infrared
Energy generally arrives at high frequencies and
is radiated at low frequencies
Gaussian surface
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Radiation Equibrium
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Thermal Conduction Heat transport within a
spacecraft
Heat flows downhill
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Thermal Conduction
Heat flows downhill
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Thermal conductivities
!!
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Spacecraft Thermal Management
Cryro-coolers are used to keep components cold
Heaters are used to keep parts warm Changing
overall absorption or emission rates used to
regulate overall temperature Thermal management
is a big mission responsibility-just like in
Florida!