> While the energy costs of rockets are individually huge they're still not a significant percentage of our global energy consumption. The limiting factor for

> While the energy costs of rockets are individually huge they're still not a significant percentage of our global energy consumption. The limiting factor for chemical rocket propulsion is not the total energy consumed, but the specific impulse (the "mileage", i.e., efficiency). This is because rockets have to carry and accelerate all their fuel with them, leading to the size of the rocket growing exponentially with the speed you want to reach. For nuclear propulsion, it's still exponential, but the exponent is much smaller. Furthermore, electricity generation using solar panels quickly becomes infeasible with growing distance from the sun.