Mount Arkan is a fictional location from the episode Sun Probe. It is a mountain in the Himalayas in Asia.
When the Sun Probe rocket is unable to pull away from the Sun, Brains realizes that a powerful radio beam is needed to fire the Probe's retros. Jeff Tracy then decides to mount a two-pronged rescue. Thunderbird 2 is sent to Mount Arkan because beams from the powerful mobile transmitter will have a better chance of reaching the Sun Probe from high up the mountain.