The International Aviation Federation (FAI) considers the space border at 100 km (330,000 ft) above sea level. So if an orbiting body goes below that altitude and continues its orbit without propulsion, do they count as two (and more) spaceflights (or a 'double spaceflight') for the FAI? Consequently they should even though it's weird.

An example would be the two GoldenEye satellites from the James Bond movie reaching an altitude of exactly 100 km and maybe lower (the FAI defines space as above, not at, 100 km).

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    $\begingroup$ Is there any reason the FAI would care if a satellite made "multiple spaceflights" as a result of its orbit crossing the 100km line? $\endgroup$ Sep 11, 2020 at 16:45
  • $\begingroup$ I recommend expanding the acronym "FAI" and adding a short description and/or link explaining what it is. $\endgroup$
    – Chris
    Sep 11, 2020 at 16:54
  • $\begingroup$ @RussellBorogove Because they defined the space border at 100 km. If a satellite goes below that line and continues orbiting without propulsion, well... $\endgroup$
    – Giovanni
    Sep 11, 2020 at 17:05
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    $\begingroup$ @giovanni - Is this question largely hypothetical? Do you know of any real-life satellites that have gone below 100 km multiple times? Also, I'm not sure that the FAI really tracks what is "in space". Finally, the only sharp border, as you describe in your comment is the ground. Anything else, you can theoretically have a rocket to get you through the atmosphere and back out. $\endgroup$
    – Carlos N
    Sep 11, 2020 at 20:09
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    $\begingroup$ This sounds like a quibble over scorekeeping for a game I'm not sure anybody is actually playing. $\endgroup$
    – Tristan
    Sep 11, 2020 at 21:01

1 Answer 1


First of all, this can actually happen. There is an effort going on to change the boundary of space to 80 km, not so much for this definition, but because technically a satellite operating at 90 km would be invading a countries air space. Below 80 km, the reentry time is no more than 2 orbits for any known mission, but a satellite can be stable for weeks below 100, particularly in an elliptical orbit.

As for what happens now, well, you won't win any records by dipping below 100 km and then back up, unless it is maintaining a low stable orbit. That doesn't seem likely to be changing anytime soon.


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