Question

Reading passage the liquid propellant rocket and alternatives answer

Answer 1

NASA had written a manual on liquid propellant rocket. It says in order to propel a vehicle in space the reaction motor present in the rocket is the only device which can do so effectively. The reaction motors comprises of ion thrusters.

The other alternative is solar sail, which is hardly used.

Answer 2

Answers of the liquid-propellant rocket and alternatives reading