3 ms·

Are any of them truly free of drag? Like, are there 0 molecules of atmosphere at some height, or just entirely negligible amounts of atmosphere for all practica

by drdeca 4y ago

Are any of them truly free of drag? Like, are there 0 molecules of atmosphere at some height, or just entirely negligible amounts of atmosphere for all practical purposes?

denkmoon 4y ago
None. In theory there are parts of space that are a true vacuum but not everywhere, and definitely not near planetary bodies. There's a reason our satellites need station-keeping fuel. https://en.wikipedia.org/wiki/Orbital_station-keeping https://en.wikipedia.org/wiki/Orbital_station-keeping
lmm 4y ago
Even in deep space there are something like two atoms per cubic meter just "there". But atmospheric density drops exponentially with altitude.
adastra22 4y ago
Yeah anything above about ~1000km or so is essentially zero drag.
- tomrod 4y ago
  It adds up. Also, Kessler syndrome potential is not negligible.
  - adastra22 4y ago
    Kessler syndrome is important but somewhat unrelated. Beyond LEO the drag is really negligible in the sense that other factors (e.g. gravitational abnormalities, the moon) have larger effects.