Complex sentence: Then called simply the "Manned Spacecraft Center," it was opened in 1961 was renamed the "Lyndon B. Johnson Space Center" (JSC) in 1973, the year Johnson died.
Split into simpler sentences: Then called simply the "Manned Spacecraft Center," it was opened in 1961. It was renamed the "Lyndon B. Johnson Space Center" (JSC) in 1973, the year Johnson died.