How does your nuclear engine in the moon square with the moon staying in orbit? Why isn't the moon gone?
On the contrary, in the Moon (Earth) there is a natural primary synthesis of hydrogen and then the following chemical elements are synthesized up to nickel-iron and the masses of the Moon and Earth increase.
In the case of any engine, we artificially “burn and consume” the mass, that is, we convert the energy of motion accumulated by Nature concentrated in the mass into neutrino radiation and thus obtain “thrust force”