Ike dollars revived the traditional size of classic U.S. silver dollars. Only about 5% were struck in 40% silver and just a portion of those in finest proof quality. Only five Ike silver dollar proof dates were struck, about 12 million coins in all. With a mintage of just 1.0 million, the 1973-S Ike silver dollar proof is the low-mintage king of the series. The Eagle-on-Moon reverse salutes America's space program begun in the Eisenhower administration.