Ohm's law

Our professor had found himself in a difficulty: during the scientific research in solar system the rocket crashed on one of the planets. The situation can be saved only be teleport connected to Earth. But then suddenly it turned out that the mechanism was destryed by somebody! Luckily Dr. Blum has with the necessary tool-kit and some spare parts to fix the teleport cabin!
The current through the teleportation system must be at some fixed value!
Help our hero to get home!