Frau Mauro - Apollo 13 Mar 28, 2010 12:01:32 GMT -4
Post by Bob B. on Mar 28, 2010 12:01:32 GMT -4
Mar 28, 2010 5:33:05 GMT -4 @capricorn1 said:This should be easy to answer and the last part of this contention I'm not fully understanding. Was the radiation from the sun completely absorbed by the outer hull then (during transit)? And did the craft rotate slowly to avoid hotspots and assist cooling. Everything making sense so far.
The spaceship both absorbed and radiated heat away. Any object in space will eventually reach an equilibrium temperature where the absorption and radiation are in balance. What that equilibrium temperature is depends on many factors, such as how much sunlight falls on it, the optical properties of the materials (black vs. white), etc.
The Apollo spacecraft was designed to reflect away a large amount of the radiation that fell on it, thus its equilibrium temperature was on the coldish side. The capsules were keep warm on the inside because of waste heat generated by the electronics. In fact, this heat was excessive and the spacecraft was equipped with a cooling system to remove the unwanted heat. A coolant was used to transport heat from the electronics to radiators on the outside of the service module.
This is why Apollo 13 got cold when most of the electronics were turned off. Without heat being added by the electronics, the spacecraft began to reach its cold equilibrium temperature.