Fifty years ago this week, American astronauts set foot on the surface of the moon, answering a call President John F. Kennedy made years earlier to send a man to the moon and return him safely to Earth.
Eight years after that call, on the morning of July 16, 1969, Apollo 11 -- with astronauts Neil Armstrong, Edwin “Buzz” Aldrin and Michael Collins -- roared off the launchpad atop a Saturn V rocket at a facility named for the assassinated president on their mission to land on the lunar surface.
In 1961, Kennedy had lobbied Congress and the American people to get behind the space program. He issued the challenge a second time in 1962 at Rice University.
“We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win…”
Answering the challenge
As he sat on the launch pad at Cape Kennedy in Florida in the early morning hours of July 16, 1969, Armstrong said he remembered being confident that he, Aldrin and Collins were about to embark on a mission that would take them into space and bring them back home again.
"I thought we had a 90% chance of getting back safely to Earth on that flight,” Armstrong told a magazine aimed at auditors in a 2011 interview.
Setting foot on the moon, which was the goal of the Apollo 11 flight, was another matter.
Credit: Neil Armstrong/NASA via AP
Credit: Neil Armstrong/NASA via AP
Armstrong said that even as the towering engines of the Saturn V rocket that would power the spacecraft to the moon and back began to vibrate, he believed the Apollo 11 team had “only a 50-50 chance” at best of making a landing on the moon on that first attempt.
“There are so many unknowns on that descent from lunar orbit down to the surface that had not been demonstrated yet by testing,” Armstrong would say, “and there was a big chance that there was something in there we didn't understand properly and we (would) have had to abort and come back to Earth without landing."
On that morning, all Armstrong could do was sit back and wait for the ride as the countdown clock headed toward the moment the three men would blastoff to exchange Earth's gravity for the moon's.
Here is a day-by-day look at the Apollo 11 mission that put man on the moon and brought him home safely.
Blastoff: July 16, 1969
It was a picture-perfect July day in Florida on the morning Apollo 11 was scheduled to lift off for a rendezvous with the moon. The ship that would take Armstrong, Aldrin and Collins into space sat on Launch Pad 39A at Cape Kennedy as the astronauts ate a breakfast of steak and eggs.
At 6:45 a.m., the three men took their seats in the spacecraft and began the pre-launch preparations. According to NASA recordings, after the men, who were not known as big talkers, were strapped into their seats in the rocket, none of them spoke for 30 minutes.
It was estimated that more than 1 million spectators lined the highways and beaches near the launch site. More than 25 million in 33 countries watched the launch live on television.
At 9:32 a.m. ET, Apollo 11 left the launch pad atop a three-stage Saturn V rocket that was carrying nearly 1 million gallons of fuel. The ship climbed straight and steady into the Florida sky with the men who built it monitoring its every moment. Twelve minutes after launch, the ship entered Earth's orbit. The spacecraft circled the Earth one-and-a-half times before the engine fired to send the ship toward the moon.
Thirty minutes after that, a maneuver was performed that separated the command module, “Columbia,” from the S-IVB, part of the Saturn V rocket. After separation, Columbia would turn around and dock with the lunar module NASA had dubbed the “Eagle.”
The rest of the first day was textbook perfect with one exception, a planned course correction was scrapped after NASA engineers determined it wasn't needed. The launch had been flawless.
The astronauts went to bed early on the first day of their journey.
Day 1: July 17, 1969
As Armstrong, Aldrin and Collins woke up and started their first full day in space, NASA put them to work updating their flight plan and performing some routine maintenance in the capsule.
At 12:17 p.m., the crew carried out a test to check how well the engines were working following launch. They fired the engines for three seconds, giving NASA enough information to judge that the vehicle was performing as it should.
Soon after the launch, Apollo 11 reached speeds of 24,000 mph, but 24 hours later, the vehicle’s speed had slowed to around 5,000 mph.
That evening, the crew appeared in a 30-minute color TV broadcast from the ship. The broadcast offered viewers a look at the Earth from a perspective nearly 150,000 miles away.
Day 2: July 18, 1969
As their second day in space dawned, Armstrong and Aldrin were tasked with checking out the vehicle in which they would travel to the moon’s surface. On live TV, the two put on their spacesuits and climbed through the docking tunnel from Columbia to the Lunar Module or LM (pronounced “Lem”).
The astronauts, now 201,000 miles from Earth, opened the hatch between Columbia and the Eagle and gave the audience at home a look at the LM, telling them it looked unexpectedly clean of items that could have been knocked loose during launch.
Bedtime for the crew on their second night was 10 p.m. At 11 p.m., Apollo 11 passed from the Earth’s gravitational pull into the moon’s. Columbia and the Eagle had slowed to around 2,400 mph by this time.
Day 3: July 19, 1969
The crew of Apollo 11 got up early on day three, around 6:58 a.m. ET, and called NASA to ask about a scheduled course correction. They were told that maneuver had been canceled and they could go back to sleep for a while.
They took advantage of the extra sleep time and began the day again after a wake-up call from NASA at 8:32 a.m.
It was a day for finalizing their preparations for landing on the moon. They had to recheck all aspects of the orbit, the descent to the moon, their time there and then their ascent to a scheduled rendezvous with Collins, who would be flying Columbia.
On July 19, the spacecraft neared the moon then flew behind it, and the crew lost contact with Mission Control. During the blackout time, the crew readied for the first lunar orbit “insertion” maneuver. In other words, Apollo 11 was about to position itself to begin orbiting the moon.
At about 75 hours, 50 minutes into the flight, the crew fired an engine that put them in an “elliptical-lunar orbit.” A second burn put Columbia and the Eagle into an orbit that would better line them up for the time when Armstrong and Aldrin would lift off the lunar surface to meet up with Collins after the landing part of the mission was complete.
Once again, the crew made a live TV broadcast from their ship, only this time it was from above the surface of the moon.
Day 4: July 20, 1969
Around 9:27 a.m. ET, July 20, the three men were up and working. Aldrin made his way into the LM to power up the vehicle with Armstrong following to begin a final check of the spacecraft that would take them to the lunar surface.
At 100 hours and 12 minutes into the fight, after Armstrong and Aldrin secured themselves into the LM, the Eagle separated from Columbia. The two vehicles continued a side-by-side orbit around the moon.
An hour and 24 minutes later, a descent engine was fired, getting the Eagle into position to begin the journey to a spot on the barren lunar landscape called the Sea of Tranquility.
A little less than two and a half hours after the ships separated, the Eagle fired the descent engine again. Collins, watching from Columbia’s window as the LM headed toward the moon, told Mission Control, "Everything's going just swimmingly. Beautiful!"
Eagle's descent was following the path Apollo 10 had taken two months earlier, and things were progressing as NASA had expected. That is, until the Eagle hit 33,000 feet above the moon's surface.
At that point in the descent, an alarm began to shriek and lights on the guidance panel began to glow. A 1202 code appeared on the onboard computer. Armstrong, his voice uncharacteristically tense, asked for answers.
“Give us a reading on that program alarm," Armstrong said.
After an agonizing few moments, Mission Control reported that the Eagle’s onboard computer was giving the 1202 error code as a warning that it was being overtaxed from processing so much information so quickly. The astronauts were told to continue their descent.
A NASA flight crew member would say later that if the computer had continued to be overwhelmed with processing information, it would likely have stopped and reset itself, something that would have likely led to Armstrong and Aldrin’s deaths.
At eight minutes after the last firing of the descent engine, the Eagle was about 26,000 feet above the moon’s surface and 5 miles from the proposed landing site.
At that time, a second alarm, this one with a “1201” code, startled the astronauts. The second alarm, NASA told Armstrong, was similar to the first, and he was told they were OK to continue the descent.
An automated targeting system was controlling the guidance of the Eagle, directing it to the landing spot NASA had chosen months before. But when the Eagle was 5,000 feet above the moon’s surface, Armstrong took over partial control of the direction of the LM. The move was planned, as Armstrong was a gifted pilot and NASA had confidence he would help land the Eagle safely.
But as Armstrong took control of guiding the Eagle to the lunar surface, he began to get a better view of the proposed landing site and quickly realized the guidance system was taking them toward a crater filled with boulders the size of cars.
Armstrong, ever the cool pilot, began to take more control of the vehicle as he looked for a safer place to set the spaceship down.
Aldrin could feel the Eagle begin to rock as Armstrong changed the Eagle’s course toward touchdown. As Armstrong looked for a new spot to set the Eagle down, Aldrin continued to call out the ship’s altitude and the rate at which it was descending.
When the Eagle was 100 feet above the surface of the moon, the men received a 60-second warning from NASA, meaning they were coming up on a point where they had to decide to abort the mission because of low fuel or to go on and land the LM on the lunar surface.
"We heard the call of 60 seconds, and a low-level light came on. That, I'm sure, caused concern in the control center," Aldrin told Space.com. "They probably normally expected us to land with about two minutes of fuel left. And here we were, still a hundred feet above the surface, at 60 seconds."
Thirty seconds after that alert, the Eagle was 10 feet above the moon’s surface in a smoother, more forgiving environment. Dust was being kicked up by the Eagle’s engines, making it difficult for the men to see just where the Eagle would be landing.
With seconds of fuel left, a blue light on the Eagle’s console blazed “CONTACT.” The metal attachments on the legs of the LM had touched the moon.
Armstrong cut the engines off.
His first words to Mission Control weren’t historic, or even a sentence. “Houston, umm…,” was all that managed to come across the communications channel.
His next words, more carefully considered, were ones people around the world were waiting to hear.
"Houston, Tranquility Base here. The Eagle has landed."
On the moon
Armstrong had set the Eagle down at 4:18 p.m. ET, and the flight plan had called for him to leave the Eagle for an EVA -- extravehicular activity -- four hours after touchdown on the moon.
Almost as soon as they touched own, the men prepared the LM for liftoff in case they needed to leave the surface quickly. The two ate a meal, then Aldrin, an elder in the Presbyterian church, radioed to Mission Control, “I’d like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours and to give thanks in his or her own way.”
Aldrin then took part in Communion, using bread and wine he had brought with him, and reading to himself from the Gospel of John. Aldrin's taking of Communion was not made public.
Armstrong and Aldrin then asked Mission Control if they could forgo the four-hour rest period and get on with the mission.
While Armstrong was preparing to step out of the LM onto the moon, Aldrin began describing what he was seeing outside of his window. "It looks like a collection of just about every variety of shapes, angularities, and granularities, every variety of rock you could find ... it looks as though they're going to have some interesting colors to them."
It took nearly four hours for Armstrong to get ready to leave the LM and begin to move down the vehicle's steps. As he stepped out of the Eagle, he released the Modularized Equipment Stowage Assembly (MESA). The assembly contained the television camera that would record his steps onto the moon.
With the camera set up, Armstrong began his trip down the stairs of the Eagle. At 10:56 p.m. ET, the first man from Earth set foot on the moon.
“That’s one small step for man. One giant leap for mankind,” Armstrong would say as his feet touched the lunar surface.
According to Armstrong, he had decided what he would say when stepped on the moon in the hours between touchdown on the lunar surface and when he left the Eagle to head down the stairs.
Twenty minutes later, Aldrin left the LM, joking that he made sure not to lock the door. Armstrong offered him tips on how best to come down the LM’s ladder.
One of the first things Armstrong did after he stood on the moon was to take a sample of lunar surface material and stow it in the LM. Should for some reason the astronauts have to make an early departure, they at least wanted a sample of the moon's surface to be returned to Earth.
On the moon, the men described the texture of the lunar surface and the landscape they saw.
"The surface is fine and powdery. I can kick it up loosely with my toe. It does adhere in fine layers like powdered charcoal to the sole and sides of my boots,” Armstrong said. “I only go in a small fraction of an inch, maybe an eighth of an inch, but I can see the footprints of my boots and the treads in the fine sandy particles.”
At one point, Armstrong called the lunar surface beautiful. Aldrin said he remembered thinking, “No it’s not.” He would describe it as “Magnificent desolation."
After about 30 minutes on the moon’s surface, the astronauts got a call from President Richard Nixon congratulating them on the success of the mission so far, saying:
“Hello, Neil and Buzz. I'm talking to you by telephone from the Oval Room at the White House. And this certainly has to be the most historic telephone call ever made. I just can't tell you how proud we all are of what you've done. For every American, this has to be the proudest day of our lives. And for people all over the world, I am sure they, too, join with Americans in recognizing what an immense feat this is.
"Because of what you have done, the heavens have become a part of man's world. And as you talk to us from the Sea of Tranquility, it inspires us to redouble our efforts to bring peace and tranquility to Earth. For one priceless moment in the whole history of man, all the people on this Earth are truly one: one in their pride in what you have done, and one in our prayers that you will return safely to Earth."
Armstrong: "Thank you Mr. President. It's a great honor and privilege for us to be here, representing not only the United States, but men of peace of all nations, and with interest and curiosity, and men with a vision for the future. It's an honor for us to be able to participate here today."
Nixon: "And thank you very much and I look forward -- all of us look forward -- to seeing you on the Hornet on Thursday."
Armstrong: "Thank you."
Aldrin: "I look forward to that very much, sir.”
During the EVA, the men placed on the moon a commemorative medallion bearing the names of three Apollo astronauts, Gus Grissom, Ed White and Roger Chaffee, who had died in a fire two years earlier during training for a space mission. Another medallion bore the names of two cosmonauts who died in accidents in Russia’s space program.
Also left was a silicon disk that contained goodwill messages from 73 countries in the world.
In the two and a half hours they were outside of the Eagle, they gathered samples of rocks and regolith, the layer of loose, superficial deposits that cover the moon’s solid surface.
Aldrin deployed the Early Apollo Scientific Experiments Package (EASEP), and Armstrong would plant a flag and harvest more rocks.
The furthest they ventured from the Eagle was about 300 feet. When they gained a bit of confidence in their ability to get around, they demonstrated a “kangaroo hop” as they skipped across the moon’s surface.
In the command module, Collins’ job was a lonely one, celebrating the fact that men had landed on the moon, but waiting and hoping his crewmates would be able to leave the lunar surface and rejoin him for the trip back to Earth.
He recorded various notes on a personal tape recorder, according to a story from Forbes, one revealing his fears for the safety of Armstrong and Aldrin.
"My secret terror for the last six months has been leaving them on the Moon and returning to Earth alone; now am within minutes of finding out the truth of the matter."
Aldrin stayed on the moon for an hour and 33 minutes before he returned to the LM. Armstrong would stay outside the vehicle for another 41 minutes after Aldrin went inside.
Before they went inside of the ship, a plaque was attached to the leg of the lunar landing vehicle that read, “Here men from planet Earth first set foot upon the moon July 1969 A.D. We came in peace for all mankind.”
The plaque had been signed by the three astronauts and Nixon.
After the EVA, the men secured the LM and went to sleep for seven hours.
The LM had two parts, the lower part, which is used in the descent stage, and the upper part which is used to get the astronauts off the moon and back into space.
The crew lived in the upper part of the vehicle, the part of the LM that would take off from the descent base and dock with the CM for the astronauts return home.
At 1:54:01 p.m. ET on July 21, 21 hours, 38 minutes and 21 seconds after the Eagle landed, the ascent stage engine fired and the top part of the LM left its base. Armstrong and Aldrin were headed for a rendezvous with Collins some 60 miles above the moon.
While many thought landing on the moon was the most dangerous part of the mission, it was actually the ascent that offered no second chance. If the ascent engine were to malfunction, the astronauts would be stranded on the moon with no hope of rescue.
As the astronauts fired the ascent engine, the LM headed upward, straight and true. They would have no problem leaving the moon.
Meeting up with Collins on his 27th revolution around the moon, Armstrong piloted the LM into the docking station it shared with the CM, and Armstrong and Aldrin crawled through the passageway into the vehicle that would take them home.
Four hours later, after transferring the materials gathered on the moon, the LM was jettisoned and fell into lunar orbit. That orbit would eventually decay and the vehicle would crash into the lunar surface, but when it did and where it landed is unknown, according to NASA.
July 21, 1969: Heading home
With Armstrong, Aldrin and a payload that included 48 pounds of rocks, the CM's engine fired for two and a half minutes to move Columbia out of the moon's orbit and aim it toward Earth.
Following the ascent, the docking and the turn toward home, the astronauts slept for 10 hours.
July 22-23,1969: Aiming for Earth
The journey back to Earth that had begun on July 21, continued through the next two days. On July 22, the crew of Apollo 11 fired the engine to make a mid-course correction, the only one needed on the trip back to Earth.
The crew would participate in two more live televised transmissions in the two days after leaving lunar orbit, and by evening, they would begin to get ready for re-entry into Earth's atmosphere.
July 24, 1969: Splashdown
As Columbia neared Earth's atmosphere, the astronauts asked Mission Control about a scheduled course correction and were told it like the other three that had been scheduled, had been canceled.
Preparations to land in the Pacific Ocean were underway, and the time came to get the ship lined up and ready to enter Earth's atmosphere.
The SM -- the Service Module that contains consumables such as oxygen, fuel, fuel cells and water -- separated from Columbia and the remaining capsule was maneuvered so that its heat shield would be in the forward position.
Apollo 11 entered the Earth’s atmosphere at 11:35 a.m. ET traveling at more than 24,000 mph. It splashed down in the Pacific about 15 minutes later some 1,440 nautical miles east of Wake Island.
The crew, wearing biological contamination suits, were helped from the capsule into a raft and lifted on the USS Hornet where they were immediately placed in quarantine in case they somehow brought back something from the moon that could infect people on Earth.
Nixon was aboard the Hornet to greet them and invited them and their wives to a White House dinner.
After three weeks of quarantine, they were deemed healthy and released from the aluminum trailer they had lived in on the deck of the Hornet.
Following the mission, the astronauts were worldwide celebrities with unending requests for their time. They were given a ticker-tape parade in New York City and Chicago and attended a state dinner at the White House.
They were in such demand, NASA put them on a world speaking tour that took them to 28 cities in 25 countries in 38 days.
While the men will always be remembered as American heroes, following the Apollo 11 mission, none of the three astronauts would return to space. Within a year, Armstrong and Collins would retire from NASA. Aldrin left NASA in 1972.