Quick caveat, I'm extremely shallow in my knowledge of any of this: >How would you prevent the puff of gas from diffusing into nothing? My thinking about this

Quick caveat, I'm extremely shallow in my knowledge of any of this: >How would you prevent the puff of gas from diffusing into nothing? My thinking about this is that at low concentrations the gas would maintain a largely ballistic trajectory and not be subject to typical diffusion properties. Would require a purpose-built accelerator to condition for 'beam' coherency. Not sure how well that scales. > Where did you get ~35km/sec? ISS orbital speed is 7.66 km/s and it only gets slower the higher you go up. Major brain-o. Ultimately I think we're on the same page of 'kinetic deorbit', just a function of what is actually feasible.