> Planets rotate so backup power is needed during nights.
This does not rule out use of solar energy.
> During interstallar journey there is time delay in communication, so it may take hours to adjust the power beam when spacecraft moves a little bit
The vehicle tracks the beam, not vice versa.
> Fusion is like solar energy just near to us and MSR will be eventually replaced by fusion reactors.
Fusion is ridiculous when examined closely. It's like fission, only far worse from an engineering and cost perspective.
> Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
Which means waste heat from a reactor in space has to be radiated at higher temperature than for a reactor here on Earth, which means nuclear is worse off there than here. In contrast, solar works better in space, as I argued upthread.
This does not rule out use of solar energy.
> During interstallar journey there is time delay in communication, so it may take hours to adjust the power beam when spacecraft moves a little bit
The vehicle tracks the beam, not vice versa.
> Fusion is like solar energy just near to us and MSR will be eventually replaced by fusion reactors.
Fusion is ridiculous when examined closely. It's like fission, only far worse from an engineering and cost perspective.
> Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
Which means waste heat from a reactor in space has to be radiated at higher temperature than for a reactor here on Earth, which means nuclear is worse off there than here. In contrast, solar works better in space, as I argued upthread.