Listen to this article

Saturday is the 50th anniversary of one of the greatest scientific achievements ever — the first time that a human being stepped on the surface of another heavenly body. And today support for the space program is greater than ever. But is the cost of more space exploration too great?

America’s great race to the moon began in 1961 at a low point in Cold War with the Soviet Union, after cosmonaut Yuri Gagarin became the first man in space and the CIA carried out a botched plan for an invasion of Cuba, then a Soviet satellite. President John F. Kennedy established the goal of putting a man on the moon by the end of the decade.

Against tremendous odds, a spectacular cost and through three different presidential administrations, the goal was met and Apollo 11 astronauts Neil Armstrong and Buzz Aldrin Jr. walked on the moon on July 20, 1969.

The success of the mission to the moon was seen at the time as a victory in the “space race” for the United States over the Soviet Union as well as a spectacular global attainment. Today, though, it is looked at with nostalgia and wistfulness. The price of another trip to a heavenly body may be just too great.

But even in 1961, there were doubts about the wisdom of spending so much money and risking lives to beat the Soviets at something.

“Anybody who would spend $40 billion in a race to the moon for national prestige is nuts,” said Dwight D. Eisenhower, Kennedy’s predecessor and commander of another great achievement, the D-Day invasion of 1944.

A recent New York Times story reminds us that scientists opposed a manned mission, arguing that money should go to robotic exploration. And 48 percent of Americans polled in 1966, when asked which government programs could be cut, cited the space program.

But 50 years later, Americans have overwhelmingly positive feelings about space exploration, polling shows, and about three in four Americans say NASA funding should be maintained or increased.

Americans’ views have grown increasingly positive, the Gallup Poll found, since 1979, when only 41 percent thought space program costs were justified. Today, 64 percent feel that way.

So, what’s next? Earlier the Trump administration said it wanted to return to the moon — where no American has been since 1972 — by 2024. But last month the president tweeted that NASA “should be focused” on Mars: “For all of the money we are spending, NASA should NOT be talking about going to the Moon — We did that 50 years ago.”

Just returning to the moon would cost $20 billion to $30 billion, NASA estimates. And a NASA-commissioned report said that exploring Mars by 2033 is not feasible.

The earliest that could happen, said the Science and Technology Policy Institute, would be 2037, with a cost estimated at more than $120 billion.

At a time when some Americans say they want free college and health care for all and others want more spent on defense, it’s difficult to see where that money — and ultimately the political support — would come from. Ten years from now, we may again be looking wistfully at the Apollo 11 mission.