Question19: Give an account of the types of method used to control the thermal environment

Tue, 09 May 2006 16:06:31 +0200

(a) Passive: adjust surface coating for absorbtivity a & emissivity e to select temperature,T(Kelvin) in solar constant Φ:
Heat in from sun + electronics heat = heat radiated away
a . sunlit area . Φ + electronics heat =e . total surface area .σ .T4
where σ is Stefan Boltzmann radiation constant
(b) Active: (in conjunction with passive)
mechanical shutters change surface finish - ratio of a to e
heat pipes move heat around efficiently
heaters stop liquids from freezing (propellant line/tanks)

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Question18: What are the main heat inputs and outputs of a spacecraft?

Tue, 09 May 2006 15:54:16 +0200

Heat Inputs: Solar radiation 1400W/M2 at Earth

Planetary Albedo -reflection

Planet- Infrared

Electronics & other (e.g.RTG)- heat dissipation

Heat Output: Only Radiation

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Question19: Give an account of the types of method used to control the thermal environment

Question18: What are the main heat inputs and outputs of a spacecraft?