Tomorrow City Projector Screen is a quest given by Gremlin Markus in Mean Street after returning from Mickeyjunk Mountain. Oswald will tell Mickey the Projector to Tomorrow City is not working, and that Gremlin Markus is working to fix it.
To complete this quest, Mickey needs to acquire 5 Power Sparks for Gremlin Markus to power the Projector Screen to Tomorrow City. Mickey can get Power Sparks by completing quests in return for them, find them in hidden locations or by buying them in the Emporium. Once Mickey has 5 Power Sparks, Gremlin Markus will use them to power the Projector Screen to Tomorrow City, so Mickey and Oswald can access the Moonliner Rocket.
This quest is mandatory and cannot be skipped. It must be completed to progress.