While looking for arguments to reopen this question I searched for a clear definition of outer space on SX. And up till now I think this definition is not made.

If we can agree on space starting after the troposphere I think the question should be reopened, since it is in the scope of "Systems with potential use in space" as mentioned in the help center.


The Karman Line is the definition of space accepted by the International Aeronautics Federation. Technically, this is the line above which an aircraft would have to go so fast to generate lift, its speed would be above orbital velocity. As that line shifts around some according to conditions, it is pegged at 100 km for convenience.

Aviation.SE is the place for your question. It deals with craft within the atmosphere. The link is to the questions containing the word 'balloon', I did a quick search to make sure those questions are handled there.

  • $\begingroup$ Thanks. I added the question to Aviation.SE $\endgroup$ – wuza Mar 1 '16 at 7:57
  • $\begingroup$ Can I accept this answer? The Karman Line is the definition of space for SX.SE. $\endgroup$ – wuza Mar 3 '16 at 12:16
  • $\begingroup$ @wuza if you feel it is a good enough answer, then you can accept it. Wherever there is the circle with the checkmark, that means you have the option of accepting an answer. $\endgroup$ – kim holder Mar 3 '16 at 14:55

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