Just as the Alphans look into the possibility of settling on a planet called Ariel, an alien probe attaches itself to an Eagle and once esconsed in the base suddenly releases what appears to be gas but turns out to be air. In record time this spreads initiating a speedy (and well realised) terraforming that gives the Moon a blue sky, a Sun and fresh air. It doesn’t take long before people start messing around in swimsuits. Its rare for an episode to contain so much that is incredulous yet to centre around a narrative that proves to be reasonably gritty for the series. The new look lunar landscape turns out to be something of a convenience for the show to undertake a `main characters stranded` episode which it does rather well.