I have read many NASA history series books on early space missions and none of them mention time dilation. In fact none mention albert Einstein or general or special relativity. Even books like "orders of magnitude" and others which show timelines of important discoveries relating to flight there is no mention. Did NASA need to factor time dilation into there missions for example voyager, or pioneer, or viking. They make no mention of it in the books. Was it classified information at the time or something, or was it just figured to be of no interest of publication?