    Sentence 1: After Apollo missions 18 and 19  were cancelled, what happened to the  Saturn Vs that were never used?    Sentence 2: The two unused Saturn Vs  became museum exhibits at the John F.  Kennedy Space Center on Merritt Island,  Florida, George C. Marshall Space Center in  Huntsville, Alabama, Michoud Assembly  Facility in New Orleans, Louisiana, and  lyndon B. Johnson Space Center in  Houston, Texas.    