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Space Exploration

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  • $\begingroup$ I didn't down vote your answer, but it's really not a helpful answer. I agree that there is not a specific, single altitude, but right now the subject is totally "up in the air", and I think working through the physics may bring out a rough answer. It's probably much higher than 100 km, but lower than 1,000,000 km, and I mentioned a particular class of engine as a guideline specifically to avoid the "it depends on the engine" excuse for leaving a non-answer as an answer. Let's see if we can work the problem as an exercise and try to narrow it down to less than four orders of magnitude. $\endgroup$
    – uhoh
    Commented Jan 5, 2018 at 14:13
  • 2
    $\begingroup$ No, a gas molecule is not just like a satellite. Due to the incredibly small mass of a molecule, it's trajectory can be and is dramatically affected by solar radiation. As well as its integrity, often being broken up in to atoms. This is how planets lose their atmospheres. $\endgroup$
    – Mark Adler
    Commented Jan 5, 2018 at 14:37
  • $\begingroup$ @uhoh I have updated my answer. $\endgroup$
    – Elijah Seed Arita
    Commented Jan 5, 2018 at 21:46
  • $\begingroup$ Yep! But remember that escape velocity depends on distance. You can't use a value that applies to the surface (or LEO) at other locations. Further, once you get farther, the Sun's gravity comes into play as well. So there will definitely be a place where the cone of expanding exhaust plume will no longer predominantly become part of Earth's atmosphere. It's unfortunate that this answer has collected three down votes, which sting a lot for a new user. You might consider in this particular case to delete it and post a new, separate answer (but don't do this repeatedly). $\endgroup$
    – uhoh
    Commented Jan 6, 2018 at 1:08
  • 1
    $\begingroup$ @uhoh I’ll take the blow. I wrote an incomplete answer and the votes reflect that. As long as the edited question gains votes back then I will be okay. $\endgroup$
    – Elijah Seed Arita
    Commented Jan 6, 2018 at 11:37