Challenges

◉ Electricity Generation

Solar Power: The spaceship rely on Photovoltaic electricity generation
Before a spaceship start a long journey, it has to circle a star to collect enough power

Carbon-based-fuel power station could produce the electricity. It can be a temperary solution on a starship, however, combusion waste has to be collected and re-processed to fuel.

Fission reactor on a spaceship is now clumsy and dangerous. The reactor generate heat as output, heat then be converted to kinetic and to electricity.
Plutonium-238 is a vital power source for deep space missions.
The fusion reactor is a more distant goal. If achieved, it is the best power source to the spaceship to drive the space engine.