It's been 50 years since the first humans walked on the moon. What comes next?

Apollo 11 Lunar Module orbits the Moon. Nasa

“The Eagle has landed,” he reported back to Mission Control in Houston. Apollo 11 and the first humans were on the moon.

The lunar module overshot its landing site by 4 miles, and with only 30 seconds of fuel left, Armstrong piloted the spacecraft to a safe touchdown.

Armstrong and Aldrin climbed into the lunar module, named Eagle. Collins stayed in the command module. The two spacecraft separated and the Eagle began its descent to the moon.

As Apollo 11 entered orbit around the moon, the astronauts prepared for the next crucial stage of the mission.

The astronauts traveled through the cosmos for the next three days.

It then docked with the lunar module, pulling it out of the section of the rocket where it was stored for launch. Apollo 11 was now ready for a lunar rendezvous.

Next, the astronauts executed a tricky maneuver to retrieve the stored lunar module that would take Armstrong and Aldrin down to the moon’s surface. The so-called command service module, where the astronauts were staying, detached from the remaining rocket stage and turned 180 degrees.

On July 16, 1969, at 9:32 a.m. ET, Apollo 11 lifted off on a Saturn V rocket from Cape Canaveral, Florida. Less than three hours later, another rocket burn put astronauts Neil Armstrong, Buzz Aldrin and Michael Collins on course for the moon, in a maneuver known as the “translunar injection.”

The four Surveyor space probes gathered information about the physical and chemical properties of the lunar soil. Together, they took tens of thousands of photos and helped NASA evaluate the feasibility of a human mission to the moon. Surveyor 6 became the first spacecraft to launch from the surface of the moon, after it lifted off and flew a short distance to another landing site. These missions set the stage for NASA’s Apollo program. The program’s first four flights—Apollo 7, 8, 9 and 10—tested equipment for a future moon landing.

The spacecraft sent back five panoramic photos, measured the lunar soil’s physical properties and helped Soviet scientists better characterize the surface of the moon.

The first of seven robotic probes sent to gather data for NASA’s Apollo program. Over 30 days, Surveyor 1 beamed back more than 11,000 photos of the moon.

Launched by the Soviet Union, Luna 9 was the first spacecraft to make a soft landing on the lunar surface.

Fifty years ago, three astronauts launched to the moon. But before humans ever set foot on the lunar surface, a series of robotic spacecraft paved the way. Scroll down to see the missions that came before Apollo 11.

Apollo 11: The people behind the mission to the moon

Even as a 6-year-old, Mark Armstrong understood what it meant that his father was going to the moon.

He understood what was happening in the days leading up to the lunar landing. He even understood why friends, neighbors and relatives kept stopping by his family’s house in Houston, often bringing food with them — “to support my mother, who must have been terrified, although she never showed it to me.”

It was only much later in life that he understood the immensity of the achievement, not only for his dad and NASA, but also for humanity.

Now, as NASA celebrates 50 years since his father, Neil Armstrong, and Buzz Aldrin set foot on the moon, people around the world are reflecting on the most memorable triumph in spaceflight history, and pondering what the next 50 years could bring.

“When I think about the legacy of Apollo, I really think about the inspiration that it provided to the young people of that generation,” Mark Armstrong said. “I want that same thing to happen now going forward.”

Neil Armstrong stepped into history on July 20, 1969, leaving the first human footprint on the surface of the moon. NASA

On July 16, 1969, astronauts Armstrong, Aldrin and Michael Collins launched into space atop an enormous Saturn V rocket. Four days later, on July 20, Armstrong and Aldrin touched down on the moon, becoming the first humans to walk on another planetary body.

The Apollo 11 astronauts returned to Earth as heroes. But their success was never guaranteed. Nor was public support in the 1960s for the country’s nascent space program.

Mike Massimino was 6 years old in the summer of 1969 and remembers watching Armstrong take the first steps on the moon from his family’s home in the suburban town of Franklin Square, New York.

“I remember very clearly thinking that this was the most important thing that was ever going to happen,” he said.

Almost 30 years later, Massimino — who would himself be selected as an astronaut candidate — still has fond memories of the months and years after the Apollo 11 moon landing, time spent idolizing the Apollo astronauts and playing in his backyard in a flight suit handmade by his mother.

“It set this passion in me that never died,” said Massimino, who retired from NASA in 2014 and now serves as a senior adviser at the Intrepid Sea, Air and Space Museum in New York City.

The world at that historic moment

The Apollo program began in 1961, born out of Cold War tensions that culminated in a fierce competition between the United States and the Soviet Union for military supremacy, technological prestige and dominance in space.

But even in the 1960s, public support for the space program was beginning to wane. The billions of dollars pouring into the NASA initiative also sparked outcry, with some excoriating the government for using tax dollars to fund journeys to space while the country grappled with serious racial inequalities at home. Gil Scott-Heron famously penned a poem titled “Whitey on the Moon,” released in an album a year after the moon landing, that called into question the true cost of the space race, and who really stood to benefit.

“If you look at public opinion polling at the time, there were a whole lot of people who thought that we were misspending our money,” said Roger Launius, the former chief historian of NASA and the former curator at the National Air and Space Museum in Washington. “And that has sort of been lost in history. Only at the time that the moon landing actually took place did more than 50 percent of the public think that it was a good idea to spend the kind of dollars we were spending to go to the moon.”

The Soviets made early strides in the space race, launching the first satellite into space in 1957, and the first human, Yuri Gagarin, four years later.

The space race

United States Soviet Union United States / Soviet Union

“The United States and the Soviet Union were locked in a struggle for control of the world,” Launius said. “Apollo was a part of that battlefield.”

In a bid to pull ahead of the competition, President John F. Kennedy set an ambitious goal for the country. In a spirited speech delivered at Rice University in Houston on Sept. 12, 1962, he committed the nation to landing an astronaut on the moon “before this decade is out.”

It was now up to a team of engineers and a crew of military-pilots-turned-spaceflyers to make that happen.

Missions to the moon

In addition to the 11 spaceflights that launched during NASA’s Apollo program, the moon has been the destination for a slew of robotic spacecraft. Since 1958, a total of 109 missions from six different nations and the European Space Agency have attempted to visit the moon — some successful, some not and even a few missions that are still going on today.

Completed missions Ongoing missions Completed missions Ongoing missions The United States has launched 47 missions to the moon, including the crewed Apollo moon missions of the 1960s and the 1970s. NASA is aiming to return astronauts to the moon by 2024. The Soviet Union launched 50 missions to the moon, beginning in 1958. The Soviets never succeeded in launching humans to the moon, but did send a series of orbiters, landers and rovers to explore the lunar surface. China has embarked on an ambitious lunar exploration program, with plans to one day build a scientific research station on the moon. In January, China became the first to land a spacecraft on the far side of the moon. Japan has launched two missions to the moon, both of which were successful. The missions collected valuable scientific observations before the orbiters were deliberately crashed into the lunar surface. The European Space Agency’s first mission to the moon was launched in 2003. The lunar orbiter tested solar-electric propulsion and communications techniques and was deliberately crashed into the moon in 2006. India’s first lunar mission, an orbiter named Chandrayaan-1, helped scientists discover evidence of water molecules on the moon. Israel’s Beresheet spacecraft attempted to make history as the first privately funded craft to land on the moon, but the probe suffered an engine malfunction during its descent to the lunar surface.

On the front lines

Louis Ramon was fresh out of college when he was hired by NASA as an aerospace engineer. It became his job to help train the Apollo 11 astronauts, test all the equipment and hardware in the lunar module that Armstrong and Aldrin would pilot down to the moon’s surface, and develop the meticulous procedures that they would follow during the mission. He remembers the fervor with which he and his colleagues approached their work during the early days of the Apollo program.

“The attitude that we all had was a commitment to support President Kennedy’s direction, and an almost war-like or military-like approach to it,” Ramon said. “We had to do this. It was like going into battle.”

At the time, many of NASA’s engineers were, like Ramon, early in their careers. Launius, who spent 12 years as the agency’s chief historian, credits some of the success of the Apollo program to the team’s youthful energy, which he says created an environment of unbridled ingenuity and willful naiveté that helped them accomplish what had once seemed impossible.

“Many of them were very young — in their 20s and early 30s,” he said. “Some have actually said in the aftermath of Apollo, ‘we were so young we didn’t know that we weren’t supposed to be able to do this. And so we did it.’ It’s a great story.”

We had to do this. It was like going into battle. —Louis Ramon

That feeling of defying expectations characterized much of Margaret Hamilton’s career in the lead-up to the Apollo 11 moon landing. One of very few female computer programmers working at the time, Hamilton was herself a pioneer. As a NASA contractor at the Massachusetts Institute of Technology, Hamilton helped develop the crucial flight software that guided the astronauts to the moon.

She remembers the hair-raising moments when two emergency alarms were tripped as Armstrong and Aldrin descended to the lunar surface.

“I would say it was about as nervous as one could get,” Hamilton recalled with a laugh. “I had written these programs over the years, but this had never happened before. And it’s, ‘Why now? Why now, just before the landing, does this have to happen?’”

Flight controllers at NASA's Mission Operations Control Room at the Johnson Space Center in Houston celebrate the successful conclusion of the Apollo 11 lunar landing mission on July 24, 1969. NASA

As it turned out, noncritical data had flooded the spacecraft’s computers and overloaded the system, triggering the alarms. The astronauts — and their spacecraft — were fine, and after adjustments were made to the computers, Armstrong manually piloted the spider-like lunar module to a safe landing on the moon, with a mere 30 seconds of fuel to spare.

Hamilton said her life was indelibly influenced by the unforgettable experience of contributing to the moon landing, and it shaped the course of her entire career.

“It totally determined what I was to do for the next 50 years,” said Hamilton, who founded her own software engineering company, Hamilton Technologies Inc. in 1986 and still serves as its CEO.

And now, five decades after the success of Apollo 11, NASA is eyeing the moon once again.

Should we go back to the moon?

A new NASA program, dubbed Artemis, aims to return astronauts — including the first female moonwalker — to the lunar surface by 2024. The bold plan, which NASA Administrator Jim Bridenstine recently estimated will cost between $20 billion and $30 billion, comes at the direction of the Trump administration.

The Artemis program’s price tag is a mere fraction of the Apollo program’s cost, which according to a 2009 report by the Congressional Research Center totaled $19.4 billion, or the equivalent of more than $116 billion in today’s dollars, but it has sparked debate about the value of returning to the moon versus exploring another destination in space, such as Mars.

Some, however, don’t see the two as being in competition. Harrison Schmitt, who flew on Apollo 17 and remains the only geologist to have walked on the moon, says lunar missions could act as a stepping stone to the Red Planet.

“If you want to go to Mars — and I think most people eventually want to do that — you have an awful lot to learn,” Schmitt said. “And the best place to learn that is on the moon, because it’s only three days away, and Mars can be as much as nine months away.”

Massimino, the 6-year-old who watched Armstrong take that giant leap for mankind, hopes the next era of human spaceflight and the rise of commercial space ventures, such as Elon Musk’s SpaceX and Jeff Bezos’ Blue Origin, can ignite the same enthusiasm in today’s youth that the Apollo moon missions did for him. The Apollo program was shuttered after the Apollo 17 mission in 1972. Kennedy’s vision had been fulfilled and a total of 12 astronauts had walked on the moon before NASA shifted its focus.

Humans haven’t been back since, but that could soon change.

“If you look at exploration, it takes a while between the first time getting somewhere for exploration’s sake and then going back and settling there,” Massimino said.

But wherever the destination, Mark Armstrong hopes his dad’s legacy, and the legacy of the thousands of people involved with the historic mission, propel the limits of human spaceflight to new heights.

“One thing that I’ve learned is that it’s hard to predict the future,” Mark Armstrong said. “One of the things about exploration is you find things you didn’t expect. So we just have to go look. And whether that’s in the depths of the ocean or on top of mountains or in space, let’s just keep looking, because I think we’ve shown over and over again that when we do that, good things happen.”

Note: Missions to the moon data as of April 2019. Success includes partial success. Distance between moon and Earth in visualizations, and their relative sizes, are not drawn to scale.

Sources: NASA, Bureau of Labor Statistics

Contributor: Jeremia Kimelman