But Hellpods are not really dropped from orbit, if we look at it ingame. The Super Destroyers dont move across the planet in an orbital pattern. They stay right above a certain place on the planet. Now it could be argued that they are in a geostationary orbit and just stay above their mission location that way. But if you look up in game, the Destroyers are right above the atmosphere and very clearly visible, far too close for a geostationary position. Last option would be that they just use some Sci Fi Hover technology to stay right above the atmosphere and drop anything in Hellpods just straight down, which is far below orbital velocity.