Astro is believed to have contracted "Space Fever" a disease which could result in having him permanently grounded from space travel, and thus, out of the Polaris Unit. During his narration, Frankie Thomas defines for the viewers just what a 3-man Space Cadet unit, like the Polaris, really is.
![Image Fate/stay night [Unlimited Blade Works]](http://i0.wp.com/image.tmdb.org/t/p/w300/jyqi5BkDoKKIA2WAoz3HBtRHld3.jpg?resize=300,450 "Image Fate/stay night [Unlimited Blade Works]")