Cristina Guidi, deputy director, Constellation Systems Division, Exploration Systems Mission Directorate, NASA Headquarters, speaks during an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)

NASA chief historian Steven Dick, seated left, shares a laugh with panelists John Logsdon, Roger Launius, Michael Neufeld, Cristina Guidi and Craig Nelson, at an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)

NASA chief historian Steven Dick, seated left, along with John Logsdon, Roger Launius, Michael Neufeld, Cristina Guidi and Craig Nelson, are seen at an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)

NASA chief historian Steven Dick, seated left, along with John Logsdon, Roger Launius, Michael Neufeld, Cristina Guidi and Craig Nelson, are seen at an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)

NASA chief historian Steven Dick, seated left, along with John Logsdon, Roger Launius, Michael Neufeld, Cristina Guidi and Craig Nelson, are seen at an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)