Wednesday marked the 45th anniversary of the launch of the most important space mission in human history. On this day, 1969, Apollo 11 lifted off from LC-39A at the Kennedy Space Center (Cape Kennedy) on the mission that would succeed in landing the first humans on the surface of another world.
On 25 May 1961, President John F. Kennedy stood before a joint session of the U.S. Congress to deliver a speech on urgent national needs.
These urgent needs included an additional $7-$9 billion over five years for the U.S.’s fledging space program, which at that time had succeed in lofting Alan Shepard on a 15-minute suborbital flight from Cape Canaveral, Florida.
With just one successful human suborbital spaceflight in the books, and with no U.S. astronaut having achieved Earth orbit, President Kennedy delivered the challenge that would drive NASA throughout the 1960s.
“I believe this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to Earth.”
NASA had its charge. The space race was in full swing. The Union of Soviet Socialist Republics had already succeeded, on 12 April of 1961, of placing the first human being into space (and Earth orbit).
NASA had lost that part of the race.
But the race to land a human on the moon was ongoing.
Building toward this goal, the Mercury Program launched six individuals on separate flights to demonstrate the ability to perform the basic tasks necessary to life in space.
Project Gemini followed, flying two-person missions to demonstrate cohabitation in space, rendezvous and docking with another vehicle, navigation, and spacewalking – all items necessary for the program that would eventually realize President Kennedy’s dream.
With the success of Mercury and Gemini, NASA turned toward the Apollo Program.
The sudden and tragic event of Apollo 1 on 27 January 1967 led to a suspension of manned Apollo flights until safety enhancements could be made to the Apollo Command Module.
As those changes took shape, the massive rocket that would take humans to the moon took flight for the first time on Apollo 4 in late 1967.
U.S. crewed Apollo flights resumed with Apollo 7 in 1968, with astronauts riding the massive moon rocket for the first time on Apollo 8 in December 1968 – a mission that took astronauts on a circumlunar mission.
And thus it became clear that NASA was on course to win the race to land a man on the lunar surface before the Soviet Union.
And this brought forward the question of what kind of message should be sent upon accomplishment of this feat.
After all, the United States would beat the Soviet Union. The U.S. would win.
But “victory” wasn’t the right message for the mission itself.
Peace was the message, and the mission insignia for the first flight to place humans on another world would symbolize this initiative.
Designed by Michael Collins, the flight patch for Apollo 11 cultivated an image of a “peaceful lunar landing by the United States.”
On the patch, the American Bald Eagle is depicted landing on the lunar surface, delivering an olive branch of peace.
The words “Apollo 11” were chosen for the top of the patch above a distant, crescent-shaped Earth.
The number “11” was chosen instead of the roman numeral “XI” as it was thought that not all cultures would understand the meaning of “XI.”
But perhaps the most important feature of the Apollo 11 mission insignia is not what was included, but rather what was not.
The names of the flight crew are nowhere on the Apollo 11 patch. The crew decided against this so that the insignia would “be representative of everyone.”
Furthering this message, and unknown at the time of initial mission planning, but symbolic of the nature of the flight, were two items that would make the journey to the moon on Apollo 11.
When the mission eventually launched, a piece of the left propeller and a piece of fabric from the wing of the Wright brother’s 1903 airplane – the first powered aircraft in the world – and a diamond-studded astronaut pin given to Deke Slayton by the widows of the Apollo 1 crew (a pin that was supposed to fly on Apollo 1) were taken by Neil Armstrong on Apollo 11.
Thus, Apollo 11 paid homage to the birth of human aviation (an event that occurred just 66 years prior) and to the human toll and loss of the goal the flight of Apollo 11 realized.
The launch vehicle:
The vehicle that would take Apollo 11 to the moon would be the tallest, heaviest, and most-powerful rocket ever built and flown: the Saturn V.
The Saturn was an engineering wonder.
Standing 111 meters (363 feet) tall, the rocket was 58ft taller than the Statue of Liberty (from ground to torch) and 48ft taller than Big Ben.
Fully fueled, the rocket weighed an impressive 6.5 million pounds and was capable of delivering 260,000 pounds to Low Earth Orbit (LEO).
The Saturn V was composed of three stages using the newly designed and built F-1 and J-2 engines.
The rocket’s systems were controlled (from just before launch through jettison of the third stage) by the Instrument Unit (IU) located atop the third stage.
The IU controlled the guidance and telemetry systems on the Saturn V and was capable of calculating position and velocity of the vehicle in real-time (and was therefore able to adjust for and correct flight deviations).
Additionally, as with all rockets, the Saturn V carried a range safety system including two primary components: the Launch Escape Tower for the crew and the rocket destruct sequence.
In the event of a launch mishap, the range safety officer would issue a command to safely shutdown the rocket’s engines.
After this, the Launch Escape Tower (or Service Module engine for later stage flight aborts) would fire to pull/separate the Command Module from the rocket and take it and the crew inside to a safe distance (and on a safe trajectory) away from the failing Saturn V.
Once the crew was safely away, the range safety officer would send another command to blow the explosive charges on the exterior of the rocket – effectively rupturing the fuel and oxidizer tanks and destroying the rocket with as little fall out as possible.
The First Stage:
The first stage of the Saturn V stood 42 meters (138 ft) tall and 10 meters (33 ft) wide and was responsible for safely lifting the rocket off the pad and delivering it to an altitude of 67 km (42 miles), a downrange distance of 93 km (58 miles), and a velocity of 2,300 meters per second (7,500 ft/s).
At liftoff, the fully fueled first stage weighed 5.1 million lbs, and the five F-1 engines generated a combined thrust 7.6 million lbf.
Steering and flight control through first stage flight was accomplished through four of the five world famous F-1 engines.
The outboard four engines were designed to gimbal while the center engine was fixed.
The Second Stage:
The second stage, by comparison, was smaller and used J-2 engines instead of F-1 engines.
Standing 24.87 m (81ft 7inches) tall and 10m (33ft) wide, this stage weighed 1.06 million lbs fully fueled (92.4 percent of the total mass of the stage was propellant).
The five Rocketdyne J-2 engines delivered 1.1 million lbf (in vacuum) via the combustion of liquid hydrogen and liquid oxygen.
Unlike the first stage which used an intertank structure to separate the propellant and oxidizer tanks, the second stage of the Saturn V used a common bulkhead from the top of the LOX tank and the bottom of the LH2 tank.
This common bulkhead was composed of a phenolic resin honeycomb structure between two aluminum sheets.
The structure successfully insulated against the 70 degree C (126 degree F) temperature difference between the two tanks, and saved the rocket 7,900 lbs in weight.
Like the first stage, the four outboard J-2 engines were gimbal-able to allow for steering and flight path control of the rocket during second stage flight. The center engine was fixed.
However, the second stage was, historically for the program, the most problematic stage of the Saturn V.
The stage suffered a destructive test stand failure in September 1965, a destructive pressure testing event in May 1966, an in-flight two-engine shutdown event on the Apollo 6 launch due to severe pogo oscillations and incorrect engine wiring, and an in-flight single-engine shutdown due to pogo oscillation on the Apollo 13 launch.
A pogo oscillation is a self-excited combustion repetitive variation in liquid fuel rocket engines that results from differential thrust between the engines of a stage.
The differential thrust thereby induces non-conformed acceleration into the rocket which negatively impacts fuel pressure and flow rate.
The stress on a rocket structure induced by pogo oscillations can be severe and cause critical damage (as happened on Apollo 6).
However, pogo oscillations can, if identified quickly enough, be eliminated by shutting down the culprit engine (or engines) before the oscillation becomes severe (as happened on Apollo 13).
The term “pogo” to describe this event in rocketry is not an acronym, but is rather a reference to the bouncing oscillation of a pogo stick.
The second stage for the Saturn V, in some ways, accounted for the possibility of pogo oscillation events.
Not only were the engines able to be shut down in the event of an oscillation, but they were also able to fire longer than the nominally planned 367 seconds – allowing the mission to continue in the event of a single or dual engine shutdown event (Apollos 13 and 6, respectively).
The Third Stage:
In comparison to the second stage, the third stage of the Saturn V launch vehicle carried just one J-2 engine, was only 17.86m (58ft 7in) tall and 6.604m (21ft 8in) wide, and weighed 262,000 lbs fully fueled.
Unlike the other two stages, the single engine on the third stage was restartable once per mission, a necessity given that this stage had to deliver the payload to Earth parking orbit and then perform the Trans-Lunar Injection burn to push the spacecraft out of Earth orbit toward the moon’s gravity field.
For third stage ascent flight, the stage ignited after second stage separation and burned its single J-2 engine for 2mins 30secs to deliver the principal payload to Earth parking orbit.
In Earth orbit, Auxiliary Propulsion System (APS) pods on the aft of the stage provided attitude control. They were also used for attitude control during lunar transfer cruise.
The APS pods were also used to settle the propellants in the tanks and feed lines prior to the Trans-Lunar Injection burn.
The Command, Service, and Lunar Modules:
Sitting atop the massive Saturn V were the crafts that would ferry the Apollo 11 crew on their voyage: the Command Module and the Lunar Module.
As was the norm in the early 1960s, NASA crews named their spacecraft. The tradition, which originated with the Mercury Program and ended on Gemini 3 when Gus Grissom named his spacecraft “Molly Brown” (a commentary on lingering questions about the sinking of his first ship, “Liberty Bell 7” on Mercury 4).
The naming tradition was halted after “Molly Brown” and did not occur for the remaining nine human flights of the Gemini Program or the initial human flights of Apollo.
The tradition returned with Apollo 9, when the Command Module was named “Gumdrop” and Lunar Module was named “Spider.”
When the Apollo 10 crew named their spacecraft “Charlie Brown” and “Snoopy,” NASA’s mood hardened toward whimsical names, and the assistant manager of public affairs at the time sent a strong message that the Apollo 11 crew be “less flippant” in their naming choice.
By this point, however, press releases had already revealed the Apollo 11 Command Module name to be “Snowcone” and the Lunar Module’s name to be “Haystack.”
The Apollo 11 crew subsequently decided to change the names, adopting “Columbia” as the name for the Command Module (after the Columbiad, the giant spacecraft fired by a cannon from Florida for humanity’s first crewed lunar mission in Jules Verne’s 1865 novel “From the Earth to the Moon”) and “Eagle” as the name for the Lunar Module (after the national bird of the United States of America).
Crew selection is an important and integral part of any space flight, but Apollo 11 had something extra to consider: the caliber of the first people – namely, the first person – who would set foot on a world other than Earth.
On 23 December 1968, as Apollo 8 orbited the moon, Neil Armstrong was offered the command of Apollo 11 and informed that NASA was planning to assign Michael Collins as Command Module Pilot and Edwin “Buzz” Aldrin, Jr. as Lunar Module Pilot (the lowest ranking position on the crew).
At this meeting, Armstrong was given the option of keeping Buzz Aldrin or replacing him with Jim Lovell (who, at that moment, was orbiting the moon as Command Module Pilot of Apollo 8).
The option was in part based on a need to ensure that all Apollo 11 crewmembers could work together without issue and also because of a crewmember swap on Apollo 8.
Collins was originally the Command Module Pilot for Apollo 8; however, back surgery necessitated his removal from that flight, and he was replaced with Jim Lovell.
Once Collins returned to active duty, he received Lovell’s spot as primary Command Module Pilot for Apollo 11.
In effect, NASA gave Armstrong the decision to choose Lovell over Aldrin and allow Lovell to retain a spot on Apollo 11 (and on the lunar landing crew of Apollo 11).
After consideration, Armstrong argued in favor of Buzz Aldrin as he did not feel it appropriate to effectively demote Lovell to Lunar Module Pilot for Apollo 11 when he had already commanded Gemini 12 and was currently serving in the number 2 position on Apollo 8.
Lovell was subsequently assigned as the back-up Commander of Apollo 11 before receiving command of Apollo 13.
With Armstrong’s decision, the crew of Apollo 11 had been determined.
However, one thing that wasn’t determined in December 1968 was who, Armstrong or Aldrin, would be the first person to set foot on the moon.
That decision would not come until March 1969 in a meeting between Deke Slayton, George Low, Bob Gilruth, and Chris Kraft.
At that meeting, the men took into consideration not physical ability (as both Armstrong and Aldrin were physically capable of being the first), but temperament and ego.
It was unanimously agreed that Armstrong did not have a big ego, and therefore, he would be the first person to set foot on the moon.
For Slayton, the decision that Armstrong would be first followed an unwritten protocol that the Commander of the mission should be the first one on the surface, not the lowest-ranking crewmember of the flight.
Officially, though, the decision was based on the manner in which the Lunar Module hatch swung when it opened.
At a 14 April 1969 press conference announcing that Armstrong would be the first person on the moon (if Apollo 11 succeeded at landing safely), NASA stated that because the Lunar Module hatch swung inward and to the right, it would be impractical to have Aldrin be first since he stood on the side to which the door would open toward.
In truth, which way the hatch swung had nothing to do with the decision that Armstrong would be first because the four men who made the decision where unaware of way the hatch swung.
With the crew determined, attention shifted to the flight vehicle.
After full stacking and integration in High Bay 1 of the Vehicle Assembly Building, the Apollo 11 rocket, atop Mobile Launcher Platform 1, rolled out to LC-39A at the Kennedy Space Center, FL on 20 May 1969.
On that same day, NASA management, mission planners, and launch personnel convened to determine the No Earlier Than (NET) launch date of the mission.
The NET launch date was set for 16 July 1969.
On 1 June, the Saturn V vehicle successfully completed flight readiness testing, and on 26 June, the Countdown Demonstration Test concluded – paving the way for final systems and spacecraft pad processing.
Unlike all previous Saturn V missions, Apollo 11continued to sail toward its NET launch date without major issue.
On 14 July 1969, the 28-hour launch countdown began at 1700 EDT, stopping periodically for planned built-in holds.
On 16 July 1969, Armstrong, Collins, and Aldrin suited up and headed to the launch pad, where their fully fueled Saturn V waited.
As Armstrong prepared to board, pad leader Guenter Wendt presented Armstrong with “a key to the moon:” a crescent moon carved from Styrofoam.
In return, Armstrong gave Wendt a ticket for a space taxi, “good between two planets.”
With the flight crew aboard, the pad leaders closed and sealed the Command Module hatch and evacuated the pad.
The countdown exited its final built-in hold at T-3hrs 30mins, 06:02 EDT.
At T-17seconds, Guidance Reference Release occurred, transferring control of the countdown and rocket systems from the firing room to the Saturn V.
At T-8.9 seconds, the Saturn V’s onboard computers sent the commands to ignite the five F-1 engines on the first stage.
As the Saturn V roared to life, engine thrust quickly ramped up to 7.5 million lbf.
Engine health checks were completed at T-1.6 seconds, with all engines verified ready for liftoff.
At 09:32.00 EDT, 16 July 1969, in front of the thousands gathered at area beaches, resorts, and river banks, as well as the millions watching on TV, Apollo 11 lifted off right on time on the first attempt.
As the massive rocket lumbered off the pad, performing the tower clearance yaw maneuver, Kennedy Space Center Chief Public Information Officer Jack King exclaimed, “Liftoff! We have a liftoff… 32 minutes past the hour, liftoff on Apollo 11.”
As Apollo 11 clear the launch tower, the rocket initiated its roll and pitch program, placing itself onto course for the climb to Earth parking orbit.
At Mission Elapsed Time (MET) 2mins 15.2secs, the center engine on the first stage was commanded through its normal shutdown procedure to limit g-force acceleration loads on the Saturn V and the crew inside the Command Module.
At MET 2mins 41.63secs, the remaining four outboard F-1 engines shut down, and the first stage separated.
Second stage ignition occurred at MET 2mins 44secs with Launch Escape Tower jettison occurring at MET 3mins 17.9secs.
Second stage center engine shutdown occurred, as planned, at MET 7mins 40.62secs. Stage two outboard engine shutdown followed at MET 9mins 8.22secs.
Third stage ignition occurred four seconds later and ended with engine shutdown at MET 11mins 39.41secs.
Earth orbit insertion was achieved at MET 11mins 49.33secs.
After two nearly complete orbits of Earth, Armstrong, Collins, and Aldrin – along with mission control – completed configuration of the vehicle for the Trans-Lunar Injection (TLI) burn.
At MET 2hrs 44mins 16.2secs, the Saturn V’s third stage engine ignited for TLI and burned for 5mins 46.73secs.
The thrust from this burn accelerated Apollo 11 to a velocity of 40,329 km/h (25,053 mph).
By that, the TLI burn brought Apollo 11 to near-Earth escape velocity, but not quite. This was intentional, and resulted in an energy-efficient transfer of the spacecraft far enough away from Earth to be “grabbed” by the moon’s gravity.
With the TLI complete, Apollo 11 began its three-day coast to the moon.
Part II of NASASpaceflight.com’s coverage of the 45th anniversary of the Apollo 11 mission will be published on 20 July 2014.
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