50 years in orbit-The oldest object in space from Planet Earth
NASA Alumni League: "Calling all Vanguardians: On March 17, 2008, the Vanguard One satellite, the oldest object in space from Planet Earth, will complete its 50th year in Earth orbit. A small group of former NRL and NASA folks has been in communication, and a number of government agencies have been asked to commemorate the event."
http://www.spaceref.com/news/viewnews.html?id=1241