First of all, during the rocket flight, the total momentum of the rocket body and ejected particles is constant, and the increased momentum of the rocket body is equal to the decreased momentum of ejected particles. Secondly, the increased kinetic energy of ejected particles and rocket bodies is provided by the combustion of propellant fuel, and the fuel also loses a large part of energy and radiates into the air as thermal pollution. Thirdly, rocket fuel combustion is a chemical reaction on the molecular surface, and the energy generated by the chemical reaction is produced by the fracture of chemical bonds, without quality defects.