The 12 Men Who Walked on the Moon

NASA / Harrison H. Schmitt
NASA / Harrison H. Schmitt

If you were born after the Apollo program, and maybe even if you remember those days, it seems almost unbelievable that NASA sent manned missions to the moon 239,000 miles away. People continue to express sadness at the fact that the Apollo lunar missions were so long ago, and that soon there will be no one left alive who actually went to the moon. Today, Alan Bean—the fourth man to walk on the moon and the last surviving member of the Apollo 12 mission—passed away at the age of 86. Which makes it the perfect time to remember—or get to know—the only 12 people who ever walked on a body other than planet Earth.


Navy test pilot, engineer, and Korean War veteran Neil Armstrong left the Navy in 1952, but continued in the Naval Reserve. He worked as an experimental test pilot for the National Advisory Committee for Aeronautics (NACA) beginning in 1955, which evolved into NASA. Armstrong was assigned as an astronaut in 1962, and flew on the Gemini 8 mission in 1966, where he performed the first successful space docking procedure. Armstrong was selected to be the first man to walk on the moon, as the Apollo 11 mission was planned, for several reasons: he was the commander of the mission, he didn't have a big ego, and the door of the lunar lander was on his side. Although the first steps on the moon are what he will always be known for, Armstrong considered the mission's biggest accomplishment was landing the lunar module. He later said,

Pilots take no special joy in walking: pilots like flying. Pilots generally take pride in a good landing, not in getting out of the vehicle.

Armstrong along with his crew were honored with parades, awards, and acclaim after their return to Earth, but Armstrong always gave credit to the entire NASA team for the Apollo moon missions. He resigned from NASA in 1971 and became a professor of of Aerospace Engineering at the University of Cincinnati for eight years. Armstrong served on the boards of many corporations and foundations, but gradually withdrew from publicity tours and autograph signings. He didn't particularly care for fame.

Neil Armstrong died on August 25, 2012, at age 82. His family released a statement that concluded:

“For those who may ask what they can do to honor Neil, we have a simple request. Honor his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink.”


After graduating third in his class at West Point in 1951 with a degree in science, Buzz Aldrin flew 66 combat missions as an Air Force pilot in the Korean War. Then he earned a PhD at MIT. Aldrin joined NASA as an astronaut in 1963. In 1966 he flew in the Gemini 12 spacecraft on the final Gemini mission.

Aldrin accompanied Neil Armstrong on the first moon landing in the Apollo 11 mission, becoming the second person, and now the first of the living astronauts, to set foot on the moon. Aldrin had taken a home Communion kit with him, and took Communion on the lunar surface, but did not broadcast the fact. Aldrin retired from NASA in 1971 and from the Air Force in 1972. He later suffered from clinical depression and wrote about the experience, but recovered with treatment. Aldrin has co-authored five books about his experiences and the space program, plus two novels. Aldrin, who is now 88 years old, continues to work to promote space exploration.


Pete Conrad was a Princeton graduate and Navy test pilot before entering the astronaut corps in 1962. He flew on the Gemini V mission and was commander of Gemini XI. Conrad was commander of the Apollo 12 mission, launched during a lightning storm which temporarily knocked out the command module's power shortly after liftoff. When Conrad stepped onto the moon, he said,

Whoopee! Man, that may have been a small one for Neil, but that's a long one for me.

Conrad later flew on the Skylab 2 mission as commander with the first crew to board the space station. He retired from NASA and the Navy in 1973, after which he worked for American Television and Communications Company and then for McDonnell Douglas.

Pete Conrad died on July 8, 1999 in a motorcycle accident. He was 69.


Apollo astronaut Alan Bean was the fourth man to walk on the moon, during the Apollo 12 mission in 1969. He was the lunar module pilot. Bean was also the commander of the Skylab Mission II in 1973, which spent 59 days in flight. Altogether, Bean logged 1,671 hours and 45 minutes in space. Bean is the only artist to have visited another world, so his paintings of the lunar environment have the authenticity of an eyewitness. He retired from the Navy with the rank of Captain, but continued to train astronauts at NASA until 1981, when he retired to devote time to his art.

Bean died on May 26, 2018 at the age of 86.


Alan Shepard was a bona-fide space pioneer who cemented his spot in history long before the Apollo program. A U.S. Navy test pilot, he was selected as one of the original Mercury astronauts in 1959. Shepard was the first American launched into space aboard the Freedom 7 spacecraft on May 5, 1961. His suborbital flight reached an altitude of 116 miles.

Barred from flight during the Gemini program because of an inner ear problem, Shepard had the problem fixed surgically and was assigned as commander of the Apollo 14 mission to the moon. He was responsible for the most accurate lunar module landing ever, and spent 9 hours and 17 minutes exploring the moon's surface outside the module. During that time, he famously knocked a couple of golf balls with a six-iron attached to his sample-collecting tool. With one arm (due to the space suit), he managed to drive further than professional golfers on Earth could ever hope to, thanks to the moon's lower gravity.

Before and after his Apollo mission, Shepard served as Chief of the Astronaut Office. He retired from NASA and the Navy in 1974, having achieved the rank of Rear Admiral. Shepard went into private business, serving on the board of several corporations and foundations. He founded Seven Fourteen Enterprises, an umbrella corporation named after his two space missions. Shepard wrote a book with Deke Slayton, Moon Shot: The Inside Story of America's Race to the Moon. Shepard compared his book to The Right Stuff by Tom Wolfe, saying, "'We wanted to call ours 'The Real Stuff,' since his was just fiction.''

Alan Shepard died on July 21, 1998 at the age of 74.


Ed Mitchell joined the Navy in 1952 and became a test pilot. Then he earned a PhD in Aeronautics and Astronautics from MIT. NASA selected him for the astronaut corps in 1966. In January of 1971, Mitchell flew on Apollo 14 as lunar module pilot, becoming the sixth man to walk on the lunar surface. He retired in 1972 and founded the Institute of Noetic Sciences, which explores psychic and paranormal events. Mitchell gained some notoriety after NASA for his views on UFOs, as he has asserted that the government is covering up evidence at Roswell. His information, he admitted, came secondhand from various sources.

Mitchell died on February 4, 2016, the eve of the 45th anniversary of his lunar landing.


David Scott joined the Air Force after graduating from West Point. Selected as an astronaut in 1963, he flew with Neil Armstrong on the Gemini 8 mission and was command module pilot on Apollo 9. Scott then went to the moon on Apollo 15, which landed on the lunar surface on July 30, 1971. It was the first mission to land near mountains. Scott and Jim Irwin spent 18 hours exploring the lunar landscape in the Lunar Roving Vehicle in the first mission to use such a vehicle to travel on the moon.

Scott became famous for the "postage stamp incident," in which he took unauthorized postage stamp covers to the moon with the intent to sell them afterwards. NASA had turned a blind eye to such activities before, but publicity over the matter caused them to discipline Scott and he never flew again. Scott retired from NASA in 1977 and served as a consultant for several movies and TV shows about the space program. He also wrote a book with former cosmonaut Alexei Leonov, Two Sides of the Moon: Our Story of the Cold War Space Race.

David Scott is 85 years old.


Air Force test pilot James Irwin became an astronaut in 1966. He was the lunar module pilot for Apollo 15 in 1971. His 18.5 hours of lunar surface exploration included gathering many samples of rocks. The astronauts' medical conditions were being monitored from Earth, and they noticed Irwin developing symptoms of heart trouble. As he was breathing 100% oxygen and under lower gravity than on Earth, mission control decided he was in the best environment possible for such irregularity -under the circumstances. Irwin's heart rhythm was normal by the time Apollo 15 returned to Earth, but he had a heart attack a few months later. Irwin retired from NASA and the Air Force (with the rank of Colonel) in 1972 and founded the High Flight Foundation in order to spread the Christian gospel during the last twenty years of his life. He notably took several groups on expeditions to Mt. Ararat to search for Noah's Ark.

James Irwin died on August 8, 1991, of a heart attack. He was 61 years old.


John Young is so far the longest serving astronaut in NASA history. He was selected as an astronaut in 1962 and his first space flight was in 1965 aboard Gemini 3 with Gus Grissom. He achieved some notoriety at that time by smuggling a corned beef sandwich onto the flight, angering NASA. But Young went on to complete a total of six space missions in the Gemini, Apollo, and the space shuttle programs. He orbited the moon on the Apollo 10 mission, then was commander of the Apollo 16 mission and became the ninth person to walk on the moon. Young was also commander of the first space shuttle flight in 1981 and returned for shuttle flight 9 in 1983, which deployed the first Spacelab module. Young was also scheduled for another space shuttle flight in 1986, which was delayed after the Challenger disaster, so the veteran astronaut never made his seventh flight. Young finally retired from NASA after 42 years of service in 2004.

John Young died on January 5, 2018 at the age of 87 following complications with pneumonia.


Astronaut Charles Duke was capcom during the Apollo 11 mission. His is the voice you recall saying, "Roger, Twank... Tranquility, we copy you on the ground. You got a bunch of guys about to turn blue. We're breathing again. Thanks a lot!" when the lunar module landed on the moon. Duke also made history by catching German measles while training in the backup crew for the Apollo 13 mission, exposing the crew to the disease and causing Ken Mattingly to be replaced by Jack Swigart on that terrifying spaceflight. Duke went to the moon (with Mattingly as command module pilot) on the Apollo 16 mission in April of 1972. He retired from NASA in 1975 having reached the rank of Brigadier General in the U.S. Air Force, and founded Duke Investments. Duke also became a Christian and a lay minister to prison inmates.

Charles Duke is 82 years old.


Jack Schmitt was a geologist first, and trained as a pilot only after becoming a NASA astronaut. In fact, he was only the second civilian to fly into space, after Neil Armstrong, who was a veteran at the time of his flights. Schmitt was assigned to fly to the moon on the Apollo 18 mission, but when the Apollo 18 and 19 missions were cancelled in September of 1970, the scientific community lobbied to have Schmitt reassigned to Apollo 17 (replacing Joe Engle) as lunar module pilot. He was the first scientist in outer space. On the Apollo 17 mission, he and Gene Cernan spent three days on the lunar surface (a record) and drove their Lunar Roving Vehicle around collecting samples, conducting experiments, and leaving measuring instruments behind. Schmitt and Cernan gathered 250 pounds of lunar material to take back.

After resigning from NASA in 1975, Schmitt, a Republican, was elected Senator for New Mexico and served from 1977 to 1983. He became an adjunct professor at the University of Wisconsin–Madison, and lives in Silver City, New Mexico. In recent years, Dr. Schmitt's scientific background and political leanings have kept him in the spotlight as he has said that the concept of climate change is "a red herring," and that environmentalism is linked with communism.

Jack Schmitt is 82 years old.


As a Navy pilot, Gene Cernan logged over 5,000 hours flying time. He was accepted into the astronaut program in 1963. Cernan's first space flight was on Gemini IX in 1966, in which he conducted extravehicular activities (a space walk), followed by the Apollo 10 mission in May of 1969, which orbited the moon. Cernan was assigned commander of the Apollo 17 mission before anyone knew it would be the last Apollo mission. Even after the Apollo program was cut, no one knew for sure that travel to the moon would be abandoned for decades. When Schmitt and Cernan boarded their lunar module for the last time on December 13th, 1972, Cernan said:

"I'm on the surface; and, as I take man's last step from the surface, back home for some time to come — but we believe not too long into the future — I'd like to just [say] what I believe history will record. That America's challenge of today has forged man's destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return: with peace and hope for all mankind. Godspeed the crew of Apollo 17."

Cernan retired from the Navy and from NASA in 1976. He went on to found an aerospace technology firm, and wrote a book about his experiences as an astronaut. He also contributed his talents to ABC-TV as a commentator during shuttle flights and has made appearances on various space specials. In September of 2011, Cernan testified before Congress on the future of the space program.

The space program has never been an entitlement, it's an investment in the future - an investment in technology, jobs, international respect and geo-political leadership, and perhaps most importantly in the inspiration and education of our youth. Those best and brightest minds at NASA and throughout the multitudes of private contractors, large and small, did not join the team to design windmills or redesign gas pedals, but to live their dreams of once again taking us where no man has gone before.

Gene Cernan died on January 16, 2017

Could an Astronaut Steal a Rocket and Lift Off, Without Mission Control?


C Stuart Hardwick:

Not with any rocket that has ever thus far carried a person into orbit from Earth, no. Large rockets are complex, their launch facilities are complex, their trajectories are complex, and the production of their propellants is complex.

Let me give you one simple example:

  • Let’s say astro-Sally is the last woman on Earth, and is fully qualified to fly the Saturn-V.
  • Further, let’s say the Rapture (which as I understand it, is some sort of hip-hop induced global catastrophe that liquefies all the people) has left a Saturn-V sitting on the pad, raring to go.
  • Further, let’s grant that, given enough time, astro-Sally can locate sufficient documentation to operate the several dozen controls needed to pump the first stage propellant tanks full of kerosene.
  • Now what? Oxidizer, right? Wrong. First, she has to attend to the batteries, oxygen, hydrogen, and helium pressurant tanks in her spacecraft, otherwise it’s going to be a short, final flight. And she’ll need to fill the hypergolics for the spacecraft propulsion and maneuvering systems. If she screws that up, the rocket will explode with her crawling on it. If she gets a single drop of either of these on her skin or in her lungs, she’ll die.
  • But okay, maybe all the hypergolics were already loaded (not safe, but possible) and assume she manages to get the LOX, H2, and HE tanks ready without going Hindenburg all over the Cape.
  • And…let’s just say Hermione Granger comes back from the Rapture to work that obscure spell, propellantus preparum.
  • All set, right? Well, no. See, before any large rocket can lift off, the water quench system must be in operation. Lift off without it, and the sound pressure generated by the engines will bounce off the pad, cave in the first stage, and cause 36 stories of rocket to go “boom.”
  • So she searches the blockhouse and figures out how to turn on the water quench system, then hops in the director’s Tesla (why not?) and speeds out to the pad, jumps in the lift, starts up the gantry—and the water quench system runs out of water ... Where’d she think that water comes from? Fairies? No, it comes from a water tower—loaded with an ample supply for a couple of launch attempts. Then it must be refilled.

Now imagine how much harder this would all be with the FBI on your tail.

Can a rocket be built that’s simple enough and automated enough to be susceptible to theft? Sure. Have we done so? Nope. The Soyuz is probably the closest—being highly derived from an ICBM designed to be “easy” to launch, but even it’s really not very close.

This post originally appeared on Quora. Click here to view.

The Science Behind Why the Earth Isn't Flat

Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.

On March 24, 2018, flat-earther Mike Hughes set out prove that the Earth is shaped like a Frisbee. The plan: Strap himself to a homemade steam-powered rocket and launch 52 miles into sky above California’s Mojave Desert, where he'd see Earth's shape with his own eyes.

It didn't matter that astronauts like John Glenn and Neil Armstrong had been to space and verified that the Earth is round; Hughes didn't believe them. According to The Washington Post, Hughes thought they were "merely paid actors performing in front of a computer-generated image of a round globe."

The attempt, ultimately, was a flop. He fell back to Earth with minor injuries after reaching 1875 feet—not even as high as the tip of One World Trade Center. For the cost of his rocket stunt ($20,000), Hughes could have easily flown around the world on a commercial airliner at 35,000 feet.

Hughes isn't alone in his misguided belief: Remarkably, thousands of years after the ancient Greeks proved our planet is a sphere, the flat-Earth movement seems to be gaining momentum. "Theories" abound on YouTube, and the flat-Earth Facebook page has some 194,000 followers.

Of course, the Earth isn't flat. It's a sphere. There is zero doubt about this fact in the real, round world. To say the evidence is overwhelming is an understatement.


Not every celestial body is a sphere, but round objects are common in the universe: In addition to Earth and all other known large planets, stars and bigger moons are also ball-shaped. These objects, and billions of others, have the same shape because of gravity, which pulls everything toward everything else. All of that pulling makes an object as compact as it can be, and nothing is more compact than a sphere. Say, for example, you have a sphere of modeling clay that is exactly 10 inches in diameter. No part of the mass is more than 5 inches from the center. That's not the case with any other shape—some part of the material will be more than 5 inches from the center of the mass. A sphere is the smallest option.

Today the Earth is mostly solid with a liquid outer core, but when the planet was forming, some 4.5 billion years ago, it was very hot and behaved like more like a fluid—and was subject to the squishing effects of gravity.

And yet, the Earth isn't a perfect sphere; it bulges slightly at the equator. "Over a long time-scale, the Earth acts like a highly viscous fluid," says Surendra Adhikari, a geophysicist at the Jet Propulsion Laboratory in Pasadena, California. The Earth has been spinning since it was formed, and "if you have a spinning fluid, it will bulge out due to centrifugal forces." You can see evidence for this at the equator, where the Earth's diameter is 7926 miles—27 miles larger than at the poles (7899 miles). The difference is tiny—just one-third of 1 percent.


The ancient Greeks figured out that Earth was a sphere 2300 years ago by observing the planet's curved shadow during a lunar eclipse, when the Earth passes between the Sun and the Moon. Some flat-Earth believers claim the world is shaped like a disk, perhaps with a wall of ice along the outer rim. (Why no one has ever seen this supposed wall, let alone crashed into it, remains unexplained.) Wouldn't a disk-shaped Earth also cast a round shadow? Well, it would depend on the orientation of the disk. If sunlight just happened to hit the disk face-on, it would have a round shadow. But if light hit the disk edge-on, the shadow would be a thin, straight line. And if the light fell at an oblique angle, the shadow would be a football–shaped ellipse. We know the Earth is spinning, so it can't present one side toward the Sun time after time. What we observe during lunar eclipses is that the planet's shadow is always round, so its shape has to be spherical.

The ancient Greeks also knew Earth's size, which they determined using the Earth's shape. In the 2nd century BCE, a thinker named Eratosthenes read that on a certain day, the people of Syene, in southern Egypt, reported seeing the Sun directly overhead at noon. But in Alexandria, in northern Egypt, on that same day at the same time, Eratosthenes had observed the Sun being several degrees away from overhead. If the Earth were flat, that would be impossible: The Sun would have to be the same height in the sky for observers everywhere, at each moment in time. By measuring the size of this angle, and knowing the distance between the two cities, Eratosthenes was able to calculate the Earth's diameter, coming up with a value within about 15 percent of the modern figure.

And when Columbus set sail from Spain in 1492, the question wasn't "Would he fall off the edge of the world?"—educated people knew the Earth was round—but rather, how long a westward voyage from Europe to Asia would take, and whether any new continents might be found along the way. During the Age of Exploration, European sailors noticed that, as they sailed south, "new" constellations came into view—stars that could never be seen from their home latitudes. If the world were flat, the same constellations would be visible from everywhere on the Earth's surface.

Finally, in 1522, Ferdinand Magellan's crew became the first people to circle the globe. Like Columbus, Magellan also set off from Spain, in 1519, heading west—and kept generally going west for the next three years. The expedition wound up back at the starting point (though without Magellan, who was killed during a battle in the Philippines). And speaking of ships and seafaring: One only needs to watch a tall ship sailing away from port to see that its hull disappears before the top of its mast. That happens because the ship is traveling along a curved surface; if the Earth were flat, the ship would just appear smaller and smaller, without any part of it slipping below the horizon.


But you don't need a ship to verify the Earth's shape. When the Sun is rising in, say, Moscow, it's setting in Los Angeles; when it's the middle of the night in New Delhi, the Sun is shining high in the sky in Chicago. These differences occur because the globe is constantly spinning, completing one revolution per day. If the Earth were flat, it would be daytime everywhere at once, followed by nighttime everywhere at once.

You also experience the Earth's roundness every time you take a long-distance flight. Jetliners fly along the shortest path between any two cities. "We use flight paths that are calculated on the basis of the Earth being round," Adhikari says. Imagine a flight from New York to Sydney: It would typically head northwest, toward Alaska, then southwest toward Australia. On the map provided in your airline's in-flight magazine, that might look like a peculiar path. But wrap a piece of string around a globe, and you'll see that it’s the shortest possible route.

"If the Earth were flat," Adhikari says, "the trajectory would be completely different." How different depends on which way the globe is sliced into a flattened map, but if it looked like it does on a Mercator-projection map, it might head east and pass over Africa.

Engineers and architects also take the Earth's curvature into account when building large structures. A good example is the towers that support long suspension bridges such as the Verrazano Narrows bridge in New York City. Its towers are slightly out of parallel with each other, the tops being more than 1.5 inches further apart than their bases. If the Earth were flat, the bottom of the towers would be separated by the exact same distance as the top of the towers; the planet's curvature forces the tops of the towers apart.

And for the last half-century, we've had eyewitness and photographic proof of the Earth's shape. In December 1968, the crew of Apollo 8 left Earth for the Moon. When they looked out of the Command Module windows, they saw a blue-and-white marble suspended against the blackness of space. On Christmas Eve, lunar module pilot William Anders snapped the famous "Earthrise" photograph. It gave us an awe-inspiring perspective of our round planet that was unprecedented in human history—but it wasn't a surprise to anyone.


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