45 Years Since Apollo 11

Neil Armstrong and Buzz Aldrin walked on the moon forty-five years ago, just a little over eight years after President Kennedy called for the US "to go to the moon in this decade."

"We choose to go to the moon. We choose to go to the moon... (interrupted by applause) we choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too."

Eight years. The US did it in eight years with computers orders of magnitude more primitive than we have in the iPhones we carry around in our pockets. Would somebody please explain to me why we haven't put an astronaut on Mars yet?