The mass, excluding the mass of the rocket vehicle itself and its propellant, which can be transported into a specified orbit by means of a rocket; i.e. the mass of the artificial satellite, spacecraft, etc., which can be carried by a rocket vehicle. This usually represents a very small fraction of the launch weight of the rocket. For example, the Atlas-Centaur vehicle used to launch the spacecraft Pioneer 11 towards Jupiter had an initial weight of 146500 kilogrammes, while the spacecraft itself had a mass of only 260 kg; in this case the ratio payload: launch weight was about 1:500. On the other hand, the Saturn 1B, with a launch weight of 600 tonnes, can place a payload of over 15 tonnes into near-Earth orbit; the ratio in this case is better than 1:40. Generally, the largest fraction of the weight of a launch vehicle is made up by propellant.
