To commemorate the fiftieth anniversary of the first successful planetary mission, Mariner 2 sent to Venus, the NASA History Program Office, the Division of Space History at the National Air and Space Museum, the NASA Science Mission Directorate, and the Jet Propulsion Laboratory invite papers for a conference relating to the history of planetary exploration. This historical symposium will be held in Washington, D.C., on 25-26 October 2012.   Please see the attached updated call for papers for more details.  The deadline for submissions is 21 February 2012.