> Also, if the mission is something like transport astronauts to the ISS, why eject any stages at all? Why not just make the rocket capable of flying to the ISS

> Also, if the mission is something like transport astronauts to the ISS, why eject any stages at all? Why not just make the rocket capable of flying to the ISS, let the whole thing dock to the ISS Essentially, Physics. To a lesser extent, practicality and cost. See The Tyranny of the Rocket Equation[1] or the "Model Rocketry" entry of xkcd What-If[2] [1] http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html http://www.nasa.gov/mission_pages/station/expeditions/expedi... [2] http://what-if.xkcd.com/24/ http://what-if.xkcd.com/24/