To do that now would entail the development of quite a new launcher and that will take time and money like hell, if I may say. Going with two stages is far more effective [...] because we could use – and this is our intention – existing launch vehicles or launch vehicles with minimal development."[1] This means that CSTS would have had a tight mass budget, as only launchers with a maximum payload capacity in the class of Ariane 5, Proton or Angara will be available for a launch. With two launches and LEO docking that means that CSTS together with an Earth Departure Stage will not be able to weigh more than about 45 to 50 tonnes in LEO (note however that this is just for the lunar spacecraft, a lunar lander is not integrated in this calculation).