Question

For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. This inability of a rocket to provide propulsion is because ...

Answer 1

Answer:

because in earlier times they designed less aerodynamic rockets with weak engines and less combustive fuel

Answer 2

For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. This inability of a rocket to provide propulsion is because rockets do accelerate in space and have been able to do so for a long time.

As per Newton's third law, the action and reaction forces will help the rockets to escape the orbit of earth.