 FAKE: To come up with a convincing effect for the floating pen in  the shuttle sequence, Kubrick decided to simply use a pen that was  taped to a sheet of glass suspended in front of the camera (in fact,  the shuttle attendant can be seen to "pull" the pen off the glass  when she takes hold of it). If you watch carefully around the upper  left corner of the screen just before she catches the pen, you can  see the glass briefly reflecting light as it rotates to give the  floating effect to the pen.