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

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Discussion Overview

The discussion explores the effects of heat transfer in outer space, particularly focusing on the temperature experiences of an individual in a vacuum without a space suit. Participants examine the roles of radiation, convection, and conduction in heat loss, and the implications of these processes in the context of space environments.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that the vacuum of space may insulate a person from heat loss, as heat transfer through conduction and convection is absent.
  • Others argue that radiation is a significant factor in heat loss, even at body temperature, and reference the Stefan-Boltzmann equation to support this view.
  • A participant questions how a vacuum can contain heat, proposing that heat loss to a vacuum by radiation would be substantial.
  • There is a discussion about the implications of radiation in a vacuum compared to pressurized environments, with some asserting that objects radiate more energy in a vacuum due to the absence of surrounding matter.
  • One participant attempts to calculate the time it would take for a human to cool from body temperature to freezing, but expresses uncertainty about the integration process involved.
  • Another participant suggests calculating heat loss in terms of watts and questions the relevance of specific temperatures like 0°C in the context of space.
  • Concerns are raised about the complexity of the calculations due to the changing power emitted as temperature decreases.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the primary mechanisms of heat transfer in space, with multiple competing views on the significance of radiation versus the insulating effects of a vacuum. The discussion remains unresolved regarding the calculations and implications of temperature changes in a vacuum.

Contextual Notes

Participants express uncertainty about the assumptions involved in their calculations, particularly regarding the integration of temperature changes over time and the relevance of specific temperature points in a vacuum.

  • #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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