http://apcnasa3ozl2j74htizuzba5b6nhugbg2qze2nrz43siunkct555fpid.onion
Once above most of the atmosphere, upper stages can be used to accelerate the vehicle up to orbital velocity. The first stage will usually use high-density (low volume) propellants to reduce the amount of volume exposed to air drag. Thus, the Apollo-Saturn V first stage used kerosene-liquid oxygen rather than the liquid hydrogen-liquid oxygen used on the upper stages.