Man builds message-receiving 'time machine'

If I want to send something forward or backwards in time (assuming that is possible) and want it to appear in the same place here on Earth (say, in a lab) I would have to take into account the Earth's rotation on it's axis, the Earth's movement around the Sun, the Sun's movement through the Galaxy, the Galaxy's movement, and so on. I don't quite see what that has to do with space dragging.