It was a time of worry and wonder, tension and transformation, fear and fulfillment.

That was the 1950s and 1960s, living in the United States not only under the threat of nuclear annihilation at the hands of the Soviet Union, but also the fear that the Soviets — in launching the first satellite, Sputnik, into orbit – seemingly proved they might soon loft a space battleship to hover above the United States, threatening Armageddon.

But the United States rallied, and in one of its finest accomplishments, not only equaled the Soviet challenge, but surpassed Moscow to become the foremost nation in space by putting men on the moon, a feat that decades later stands unparalleled.

Those heady daunting days of rising to a vast challenge riveted Americans, as they watched a generation of heroes soar into space, the new generation President John Kennedy said had received the torch in the race of global competitiveness.

Unlike some recent competitions against other nations (think global trade and Iraq), the 1960s space saga ended with the United States triumphant and loved around the world, if but for a little while.

A new movie now playing, "In the Shadow of the Moon," (Think Film, Discovery Film, others) brings back those singular times and the remarkable men who led the way to another heavenly body, the Apollo crew members who braved the unknown in lunar missions.

This is a film of the first order.

While it has some magnificent action video shots, such as an Apollo capsule in its final burn heading into the blackness on a mission to the moon, or close-ups of rockets lifting off amidst a blizzard of falling ice chunks, some of the most fascinating scenes are quiet moments in which Apollo astronauts recall just how it was, when they faced fear mixed with fascination and exultation.

Their faces fill the screen in close-ups, while they give low-key remembrance to some of the most exciting moments in the history of the 20th century, a history writ large by these modest men.

This was, keep in mind, a time when rockets exploded or nosedived into the ground, long before fatal accidents such as the Space Shuttle Challenger tragedy became rarities.

These were individuals willing to risk their lives to step into an unknown realm, to push far out the boundaries of human presence.

Were they frightened? One astronaut concedes to being "worried … concerned."

At another point, Alan Bean, the lunar module pilot on Apollo 12, man’s second lunar landing, recounted his surprise at the violent trembling of the rocket as it thundered to life and blasted into the Florida sky. "It shakes and vibrates more than I ever imagined," he said.

Another Apollo astronaut, Charlie Duke of Apollo 16, the tenth man to walk on the moon, said that monitors on his body showed that "my heartbeat at liftoff was 144" beats per minute, rather than a more normal 60 or so.

Bean also recalled that in the long quarter-million-miles journey to the moon, he looked out the window in the module, knowing there was a lethal vacuum on the other side of it. "There’s death out there, about an inch away," if the window blows out, he recalled thinking back in November 1969.

He also remembered how it felt when — after flying in sunshine all the way to the moon — the module went into orbit and flew behind the moon, and suddenly there was darkness. "We’re in the shadow of the moon," Bean recalled his awestruck thought at the time.

Or, there is the gut-churning final descent of the lunar lander, trying to avoid landing atop boulders on the moon, as propellant ran low. Back on Earth, it sounded easy, as the world heard that "the Eagle has landed."

There is so much fascinating material in this film: the liftoff from Pad 39A of Apollo 11, the first mission to the moon in July 1969, carrying Neil Armstrong, Edwin "Buzz" Aldrin and Mike Collins on the first human journey to another sphere.

And better yet, we see it through the eyes of a newsman, Walter Cronkite of CBS News, reporting the mesmerizing event as it occurred.

Astronauts also describe in restrained, matter-of-fact tones such things as the difference between low Earth orbit flight, where the curve of the Earth is not great and it almost seems flat, and the sight of the Earth from hundreds of thousands of miles away, where the whole circle of the planet is visible.

Only two dozen human beings, the Apollo astronauts, have witnessed that with their own eyes.

And there is a calm recollection that an astronaut for three days of his life called the moon home, and intimate scenes such as opening letters from home that were carried along on the mission, or the huge pleasure taken in such a small, simple act (if one were on Earth) of shaving upon arising.

While there was much controversy about the United States, then as now mired in an unpopular war (Vietnam at that time, versus Iraq today), what rivets one’s attention is how — thanks to NASA and its moon-shot program — people around the world cheered theUnited States on, and for a moment at least America and Americans were admired and loved.

In Africa, in France, in the Pacific, in Japan, around the world, people crowded about TV sets to watch in delight as fellow members of the human race entered a new realm.

In a marketplace, at a major-league baseball game, in venues giant and tiny, people were riveted by brave men.

And what a wonder they watched.

Some shots show just how small a place the barren moon really is, with a horizon seemingly close enough to reach out and put your hand on it.

But it also was awesome, Duke said, a beautiful place unspoiled and untouched by man.

Wonder and worry intermingled throughout the Apollo missions.

For example, what if a successful landing on the moon were to be followed by a rocket failure on the lunar lander, and two astronauts were stranded on the moon, a fatal 250,000 miles from their life-sustaining home, Earth?

The film includes the beginning of an address that President Richard Nixon prepared, just in case that tragedy occurred, but thankfully it was a video that never had to be aired.

Then there is the long voyage back to Earth, reentering the atmosphere at 26,000 miles an hour, beginning some 400,000 feet above the planet and plunging fiery hot down to 90,000 feet. Finally, triple parachutes pop open, and the Apollo spaceship splashes down in the Pacific Ocean, its brilliantly deep blue waves a strong counterpoint to the pale grays of the colorless lunar surface.

Today, that era of lunar travel and excitement is long gone, with U.S. space shuttles able to travel only to low Earth orbit, until they retire in 2010, after which the United States won’t even be able to do that for half a decade until a new spaceship, Orion-Ares, is ready for its first manned flight.

It will be perhaps another half decade before Americans return to the moon, and more than a decade later before they set foot on Mars.

So the Apollo program, a mid-20th century Herculean effort, will stand for a very long time in the 21st century as the high-water mark of NASA craftsmanship and leadership.

Though long-gone, this film brings it all back for those who wish to see again America in all her glory as the foremost technological power in history.