Thirty-six years ago this week, three astronauts and their families demonstrated the courage, boldness, and determination necessary for the human race to conquer the stars. The question is whether NASA and Congress today are willing to show as much bravery.

It was Christmas week, 1968. In many ways, the political situation was comparable to the present. The country was at war. Lives were being lost on a daily basis in a distant land against an implacable and ruthless enemy.

The nation also had just completed a bruising Presidential campaign, in which protests and mud-slinging over the war had dominated the news.

On other ways, however, the situation in 1968 was much worse than today. The year had seen violent riots in almost major city in the United States and Europe. The Soviets had invaded Czechoslovakia, choking off the democratic movement there while reaffirming once again their unwillingness to reform their totalitarian regime.

Political assassinations had killed both Martin Luther King and Robert Kennedy.

Then, during Christmas week 1968, the trio of astronauts had embarked on a journey to the moon, encased in their tiny Apollo 8 capsule with only enough spare oxygen to sustain them for about two weeks. The war, the campaigns, the assassinations, the riots — all these issues were distant tragedies to them and to the engineers on the ground who had built the spacecraft.

The astronauts — Frank Borman, Bill Anders and Jim Lovell — had volunteered to do something noble, courageous and bold. They had no time to worry about earthbound squabbles.

Borman was the commander. Though his wife, Susan, had given him her total support, he knew she was terribly frightened by the possibility he would not return alive. Only a few weeks earlier, Christopher Kraft, NASA’s director of flight operations, had paid her a personal visit, trying to ease her fears.

Craft had explained to Susan Borman that she should not lose hope, because the chances of success were not zero. Everyone at NASA believed the odds that the men would come home alive were as much as 50 percent.

The wives of the other two astronauts had been told similar stories, and had nonetheless encouraged their husbands to go. When Bill Anders had asked his wife, Valerie, what he should do, she had adamantly told him he had to go, even though they had five children under age 11 and a limited income. Not only was the flight’s success important to the world and the nation, but it also was what he had been working for all his life.

Likewise, Marilyn Lovell had put aside her fears and reservations to support her husband. The mission was Jim’s childhood dream come true. How could she stand in the way of that?

The risks were daunting. For one thing, the Saturn V rocket the three men would use to get to the moon had only been tested twice before and, in its last test, developed serious problems, including the premature shutdown of two of the rocket’s second-stage engines as well as the failure of the third-stage engine to re-ignite on command.

For another, the mission criteria required that before any crew was launched out of Earth orbit, they would carry both an Apollo capsule and a lunar module. Should there be problems with the capsule, the LM could act as a temporary lifeboat until the crew got home — which is exactly what happened during the Apollo 13 mission in April 1970. The LM in that case saved Jim Lovell’s life.

When Apollo 8 was launched toward the moon on Dec. 21, 1968, however, the LM was not yet ready, so the crew had no such lifeboat. Had what happened on Apollo 13 happened on Apollo 8, Jim Lovell would have been dead in less than two hours.

Despite such obstacles, the astronauts, their families and everyone at NASA had made the decision that the flight had to go onward. As Borman said during the news conference announcing the mission, We take our increased share of risk in order to make the flight following ours much safer.

Everyone understood the dangers of space exploration, and did not shirk from those dangers. For humanity to conquer the stars it was necessary for spacefarers to have a willingness to die for their task. Otherwise it simply could not happen.

So, during Christmas week 1968, Borman, Anders and Lovell put themselves into a small capsule about the size of a mini-van and let themselves be launched into lunar orbit, believing full well there was only an even chance they would return to Earth safely.

They did return, to glory and honor. Their success won the space race, forcing the Soviets to abandon their efforts to reach the moon. Apollo 8’s images from orbit did more to ignite the environmental movement than any protest demonstration. The astronaut’s words, including a reading from lunar orbit of the first 10 verses of the Book of Genesis on Christmas Eve, helped change the world’s perception of Earth’s place in a black, infinite universe.

Bill Anders said on the way home: “As I look down on the Earth here from so far out in space, I think I must have the feeling that the travelers in the old sailing ships used to have, going on a long voyage from home. I have the feeling of being proud of the trip, but still happy to be going home.”

Today, a new generation of space explorers faces similar choices and has exhibited a similar willingness to confront death so the human race can conquer the stars.

Both Mike Melvill and Brian Binnie, test pilots for the company that had built SpaceShipOne, understood that for them to win the Ansari X Prize, they had to be willing to die when they flew their ship. They were willing and thus won the prize.

The passengers who inevitably will pay to fly on ships like SpaceShipOne also must be willing to die for the honor. They will not need any government warnings or safety regulations to tell them of the risks.

The next shuttle crew will face similar dangers, flying on a spacecraft that twice before has cost the lives of astronauts and whose safety cannot be guaranteed. Without a willingness to die on the crew’s part, the shuttle cannot fly.

When the next NASA administrator gives the go-ahead for the next mission to leave Earth orbit and head for the moon — like Apollo 8 — he or she will have to have the same courage as the people at NASA 36 years ago.

Moreover, just as the American people had accepted the risks and supported NASA’s administrators when they sent the Apollo missions to the moon, today’s public must give the next NASA administrator, the first private space tourists, and the pilots who fly them as much support. When something does go wrong again — as it surely will — everyone involved must accept the consequences of living life dangerously, say a prayer in memory and move forward boldly.

That the nation appears increasingly enthusiastic about braving these dangers in this manner bodes well for the U.S. space program.

Robert Zimmerman is an independent space historian and the author of the book Genesis: the Story of Apollo 8. His most recent book, Leaving Earth, was awarded the Eugene M. Emme Award by the American Astronautical Society for the best popular space history in 2003.