(bound form) base; foundation / (bound form) radical (chemistry) / (bound form) gay (loanword from English into Cantonese, Jyutping: gei1, followed by orthographic borrowing from Cantonese)
基
=
其
+
土
:
Joan of Arc (ji) has to repair the watchtower (其) In front of the space station (Ø1). The tower needs a new foundation (基), and because it is floating in outer space, Joan of Arc can just add some dirt (土) to its base (基) to create a new foundation.
础
=
出
+
石
:
Chantal Chicken (chu) has to leave the space station (Ø3) quickly, but the emergency exit (出) is blocked by a big rock (石). Chantal has no other choice but to dig a tunnel through the space station's foundation (础).