caption: This undated handout photo provided by the National Air and Space Museum, Smithsonian Institution shows a Star Trek starship Enterprise studio model. The model of the fictional Starship Enterprise will go on display in the reimagined Boeing Milestones of Flight Hall. For the first time since its 1976 opening, the <PERSON>'s National Air and Space Museum plans to overhaul its central exhibition showing the milestones of flight. The extensive renovation announced Thursday will be carried out over the next two years with portions of the exhibit closing temporarily over time, said Museum Director <PERSON> `` <PERSON>. (AP Photo/ <PERSON>, National Air and Space Museum, Smithsonian Institution )