When satellites or space stations orbit the Earth, they are constantly experiencing a low level of aerodynamic drag from Earth's atmosphere. The ISS needs to be reboosted every few months to account for this drag.

My question, is if running into gas molecules at orbital velocities of ~7800 m/s causes meaningful erosion, that is can be impact of these atoms and molecules actually break molecular bonds and knock atoms or molecules free from the surfaces of satellites?

As a first order approximation, the amount of kinetic energy in 1 mol of nitrogen gas travelling at 7800 m/s is equal to 850 kJ, this is very comparable to to the bond dissociation energies in organic compounds which tend to be around 400 kJ/mol, implying that impacts from nitrogen molecules should be able to tear organic compounds apart. But on the other hand the bond energies in crystalline and metallic solids can be much higher and presumably light gas molecules would just bounce off such surfaces.

This question is related but at best is only a partial answer since there is no mention of kinetic impact of molecules. It can be reasoned that since they aren't mentioned the effect, if any, must be insignificant relative to other sources of erosion such as corrosion caused by the chemical reactivity of atomic oxygen, however I find this unsatisfactory as it is merely a logical deduction whereas this should have a straightforward answer at least in principle, such as "yes, but it's insignificant compared with other sources of erosion" or "no, the chemical bonds in metals are so much stronger than the kinetic energy of the gas molecules that the impacts merely cause a little heating that is harmlessly dissipated".

  • $\begingroup$ Short answer, Yes. Take a look at this, probably it's a duplicate. space.stackexchange.com/questions/30980/… $\endgroup$ Commented Mar 7, 2019 at 19:25
  • $\begingroup$ I never thought about that before, ever N2 molecule would have a kinetic energy of almost 9 eV relative to the orbiter, yikes! Expressed as a temperature that's like ~100,000 K. It's a good question, but I've marked it as a duplicate of What are the long term effects of Space Weathering on man-made materials? There are several good answers there. Beyond the kinetic energy, there are already ionized species and dissociated atomic species like monatomic oxygen which is pretty reactive as well. $\endgroup$
    – uhoh
    Commented Mar 8, 2019 at 1:41
  • 4
    $\begingroup$ I've updated the question. What I'm really interested in is the kinetic impacts which the linked question does not mention at all. The question is not "does erosion occur" but "does erosion occur due to the high kinetic energy of the gas molecules" and if not why not? $\endgroup$ Commented Mar 8, 2019 at 9:42
  • $\begingroup$ Whelp, here's a bunch of stuff about particle attrition, but a single molecule of oxygen? No idea. Is that even observable? $\endgroup$
    – Mazura
    Commented Nov 6, 2019 at 2:04


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