(NBC) - Forty years ago today, the nation saw something that stretched the imagination: American astronauts walking on the moon.
Monday morning, Apollo astronauts celebrating the anniversary sat down to remember their mission.
"That's one small step for man, one giant leap for mankind," are the famous first words from Neil Armstrong, the first man to set foot on the moon.
It was those words, 40 years ago today, that opened a new door.
Neil Armstrong instantly catapulted America to the forefront of space exploration.
"The greatest legacy we have, I think, from Apollo is the inspiration it provided for those young dreamers who followed in the space program," said Apollo 10 and 17 astronaut Eugene Cernan.
Cernan was the last astronaut to set foot on the moon.
"I really believed we'd be back to moon by end of that decade and on way to Mars by turn of century. My glass has been half empty for three decades," he observed.
And there's disagreement on what the next step should be.
"There's a lot still to be done on the moon!" insists James Lovell, astronaut aboard Apollo 8 and 13.
"America to Mars is what it ought to be, not America back to the moon," counters Buzz Aldrin, the second man to walk the moon.
But a trip to Mars could cost far more than $100 billion.
The U.S. has already spent that on building the International Space Station, and in these tight economic times, with hundreds of thousands of jobs disappearing every month, the biggest concern may be whether America can afford to explore.
"Until we're willing to pay the price, the American public is not going to have a very aggressive space program again," argues Walter Cunningham, Apollo 7 astronaut.
The glory days of space exploration are now history, and America's future in space is unknown.
NASA's budget right now is almost $18 billion.
President Obama's asking for almost another billion next year, but then leveling off after that through 2014.