Thunderbirds Are Go!: Season 3, Episode 4

3 - 4: Night and Day

The Gray and Houseman mining operation now includes planet Mercury; it uses a moving vehicle that stays on the 'dark side' of the planet. However, when a malfunctioning pod leaves the vehicle stranded - and with the sun's blazing 'terminus' drifting ever closer -International Rescue are summoned to solve the problem.