[lmm]

Landing/recovering aircraft on an airship is proven technology, and hooking a tether onto something as it falls through a buoyant atmosphere is quite possibly easier than stopping a rocket precisely at ground level where any screwup will turn it into a crater immediately (as is the case for Mars). Yes the balloon needs to be able to adjust its buoyancy to maintain stability but that was always a requirement; sinking into the atmosphere is a relatively slow process as long as your balloon is big enough. Likewise air-launched rockets are already proven technology - you can either just let the rocket drop away far enough for clearance before lighting its engines, or if you're feeling fancy then the rocket uses its own sacrificial balloon to rise as high as possible in the atmosphere before launch (of course that means you have to be able to manufacture balloon fabric or arriving rockets have to bring their own until you reach that stage, but that doesn't seem insurmountable).