In practice, it is found that it can be more efficient to launch rockets in stages, where part of the rocket structure drops away when it is no longer needed, thus decreasing the amount of mass that n...In practice, it is found that it can be more efficient to launch rockets in stages, where part of the rocket structure drops away when it is no longer needed, thus decreasing the amount of mass that needs to be placed in orbit. When all the second-stage fuel was spent, it too separated and and dropped away, and the third stage engine ignited, which placed the spacecraft into Earth orbit.
