Originally Posted by **Kamil19991** After watching the interstellar movie I have a question: which solution will consume less fuel? The space station moves in a circular orbit and has too slow speed. To increase it has two possibilities:
1. Increase the orbital speed,
2. Increase the height of the orbit, and thus reduce the first space velocity. |

I don't know the answer off the back of my hand. Simply determine the energy in each case. The one requiring the lesser energy will require less fuel.

The energy is the sum of the gravitational potential energy U = -GMm/r^2 and the kinetic energy K = mv^2/2. The orbital requirement is for the centripetal force to be equal to the gravitational force in magnitude.