His presentation for a new lunar rover design successfully completed and creating lots of excitement amongst the management, Mutta focuses his sights once again upon reaching the moon.
This desire is once again increasing in its urgency as letters from Sharon become rarer and with poorer handwriting, suggesting a deterioration in her condition. Little does Mutta know that is that the chief is continuing to worry about what adding Mutta to a lunar mission might do for his brother's confidence and motivation as he continues to suffer from a panic disorder following his lunar accident.
To further flesh this train of thought out, we look back into Butler's past, and his own experiences with a former colleague who suffered from a panic disorder after a training jet accident which prevented him from ever stepping foot on the moon or completing his training. This also ties into Mutta's grand plan to impress Butler - after looking up his past on Wikipedia he decides to recreate the vertical roll climb that Butler saw as both a proof of his intent to reach the moon and the turning point where he could be seen as a proper pilot.
All of this combines to create another simple but effective episode of Space Brothers that doesn't move the story forward by any huge amount but still does a good job of building its characters and providing another interesting story via its cast that never feels superfluous to proceedings. Beyond this, it's also nice to see Mutta getting things right and applying himself with confidence, which suggests a fair amount of development compared to the uncertain character we were following earlier in the series - a little touch which is exactly the kind of thing that keeps me watching week in, week out.