1: Setting aside the issues of Halachically defined time in space, and ignoring the physical constraints limiting a spacecraft from having Schach mounted properly, how should Schach be oriented to fulfill the Mitzvah of Succah? Would one simply need Schach on the side that faces the sun (so long as it always faces the sun), or would one need Schach on all 6 sides of one's spacecraft since the sky is everywhere?
2: From a purely theoretical perspective, if a device existed in real life that enabled the creation of space portals such that both portals led to one another like from the game "Portal", and a person created a portal connecting the floor of a Succah to the ceiling of a room from a house, could one fulfill the Mitzvah of Succah from being underneath the portal, and hence underneath the Succah? If it rains, the rain falls through the Schach, falls into the portal, and then teleports to the room's ceiling. The room's ceiling is almost completely replaced with a large gaping hole, connected to the Succah.
3: Again, theoretically, if there was no sun, would one still need Schach to shade anything (ignoring the imminent ice age to follow)?