Will I Freeze or Burn in Outer Space? A Look at Heat Transfer in Space

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SUMMARY

The discussion centers on the thermal dynamics of space, specifically addressing the misconception that space is uniformly cold. Participants clarify that while the vacuum of space minimizes heat transfer via conduction and convection, radiation remains a significant factor in heat loss. The Stefan-Boltzmann equation is highlighted as a crucial tool for calculating radiative heat loss, with examples illustrating that a human body can lose substantial heat in space, leading to hypothermia. The conversation concludes that while immediate freezing may not occur, the cold of space can be lethal within minutes.

PREREQUISITES
  • Understanding of heat transfer principles, specifically conduction, convection, and radiation.
  • Familiarity with the Stefan-Boltzmann equation for calculating radiative heat loss.
  • Basic knowledge of thermodynamics and thermal equilibrium.
  • Awareness of human physiology related to temperature regulation and metabolic heat generation.
NEXT STEPS
  • Study the Stefan-Boltzmann equation in detail to understand its application in thermal radiation calculations.
  • Research the effects of vacuum on human physiology, particularly in terms of heat loss and survival time.
  • Explore the differences between heat transfer in a vacuum versus in an atmosphere, including practical implications for space travel.
  • Investigate thermal insulation technologies used in space suits and spacecraft to mitigate heat loss.
USEFUL FOR

Aerospace engineers, physicists, space enthusiasts, and anyone interested in the effects of thermal dynamics in space environments.

  • #31
http://en.wikipedia.org/wiki/Space_suit:

Since the temperature on the outside of the suit varies greatly between sunlight and shadow, the suit is heavily insulated...,


Exposure to space without a spacesuit
The human body can briefly survive the hard vacuum of space unprotected[2], despite contrary depictions in much popular science fiction. Human flesh expands to about twice its size in such conditions, giving the visual effect of a body builder rather than an overfilled balloon. Consciousness is retained for up to 15 seconds as the effects of oxygen starvation set in. No snap freeze effect occurs because all heat must be lost through thermal radiation or the evaporation of liquids, and the blood does not boil because it remains pressurized within the body. The greatest danger is in attempting to hold one's breath before exposure, as the subsequent explosive decompression can damage the lungs. These effects have been confirmed through various accidents (including in very high altitude conditions, outer space and training vacuum chambers).[3][4] Human skin does not need to be protected from vacuum and is gas-tight by itself. Instead it only needs to be mechanically compressed to retain its normal shape. This can be accomplished with a tight-fitting elastic body suit and a helmet for containing breathing gases, known as a Space activity suit.
 
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  • #32
Interesting post about bodily effects of outer-space exposure.

Consider that while your body is radiating away heat, the sunlight you would be exposed to would be more direct than even the clearest day at noon on the equator. It is hard to reconcile the idea of such intense sunlight with cold as a result of the body radiating out energy, especially considering the vacuum prevents you from transmitting heat into air molecules. I wonder how dry your skin would become and how quickly. Would you become leathery after a few seconds? I suppose mummification would be the result of too long of exposure, but I suppose the mummified corpse wouldn't last long in sunlight that hot.
 

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