In his 1962 "We Choose to Go to the Moon" speech, President John F. Kennedy said: "If this capsule history of our progress teaches us anything, it is that man, in his quest for knowledge and progress, is determined and cannot be deterred. The exploration of space will go ahead, whether we join in it or not, and it is one of the great adventures of all time, and no nation which expects to be the leader of other nations can expect to stay behind in the race for space." What is Kennedy's claim in this excerpt?