Forty-nine Years Ago Today…

…men from Planet Earth set foot upon another world.

Will you celebrate?

Perhaps, next year, on the 50th anniversary, we should host a global celebration synchronised with the events half a century before.

(I have defined “today” using the conventional date of 1969-07-20 in my local time zone.  The actual landing occurred at 20:18:04 UTC on 1969-07-20 and the first footstep on the Moon was at 02:56:15 UTC on 1969-07-21.)

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

10 thoughts on “Forty-nine Years Ago Today…”

  1. There were so many details to produce the components, systems, procedures, infrastructure, training, and on and on and on —  done by diligent Americans in the 60s and early 70s,I will always be in awe of this accomplishment — to land humans on the moon and return them safely — and done within a decade of President Kennedy declaring the goal.

    Discovery, invention, adventure — it is all in the story of the lunar landing and much more.

    I’ll fly my U.S. flag, and fly a few of my drones as a tribute to the pioneering lunar mission, and to future missions that advance our knowledge of the vast undiscovered universe!

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  2. It was a world event. I was that old at the time and never thought how dangerous the moon landing was. The lunar modules ascent stage engine was never tested outside a lab till it was finally lit to bring our astronauts home.

    I remember Life put a flimsy record in its pages that you could play on a phonograph the first words of Neil Armstrong on the moon.

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  3. I remember the night before brushing my teeth and wondering how the landing would go.  The landing itself was tense with the TV simulations having us on the Moon well before the landing of the Eagle.

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  4. We had gone to see Chitty Chitty Bang Bang, which was unusual because my dad never went to the movies. We came back and went to bed. Mom came in and woke us up to watch. TV from the moon: utterly astounding.

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  5. 9thDistrictNeighbor:
    We had gone to see Chitty Chitty Bang Bang, which was unusual because my dad never went to the movies. We came back and went to bed. Mom came in and woke us up to watch. TV from the moon: utterly astounding.

    Wasn’t Chitty Chitty Bang Bang written by Ian Fleming? My aunt sent me that book. At the time, I didn’t think a book was a good gift.

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  6. I was repairing a monochrome tube TV and watched it on that at the time.

    I can’t get over the chances that were taken with the computer and software available in the LEM and well it’s just fascinating that those brave men did what they did.

    Brave SOBs they were!

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  7. 10 Cents:
    The lunar module’s ascent stage engine was never tested outside a lab till it was finally lit to bring our astronauts home.

    This is not the case.  The lunar module descent and ascent engines has been tested three times in space prior to being used on Apollo 11.  The lunar module was first tested in Earth orbit in the unmanned Apollo 5 mission in January 1968.  The lunar module was launched by itself on a Saturn IB booster (the same one which was to have launched Apollo 1, and was undamaged by the spacecraft fire that killed the astronauts).  Under command from the ground and its onboard computers, the LM performed firings of the descent and ascent engines simulating a descent toward the moon.  The ascent engine was tested in the “fire in the hole” configuration which would occur in an abort during the descent.  Due to a change in plans which was not adjusted for by the on-board computer, there was an initial problem firing the descent engine, but this was corrected by ground commands.  The ascent engine worked as designed, performing two burns.  There was no plan to recover the lunar module, and it burned up in the Earth’s atmosphere a few days later.

    On Apollo 9 in March 1969 the command/service and lunar modules were tested in Earth orbit by a crew.  All of the maneuvers which would have been done in a lunar mission were done including undocking the LM, burning its descent engine to simulate a landing, then using the ascent engine to return to the command module.  A spacewalk was performed to demonstrate the ability to return to the command module from the lunar module if docking were to fail or the tunnel between the two craft were obstructed.  There were no problems with any of these maneuvers.

    Apollo 10, in May 1969, tested the spacecraft in lunar orbit.  The LM descent engine was burned as it would be in a landing mission to lower its orbit to 15.7 km above the lunar surface.  This was the same trajectory in the same location as Apollo 11 would fly.  Rather than continuing to burn toward a landing, the ascent engine was then fired to raise the orbit and return to the command module.  There was a brief loss of control when the ascent engine fired, but this was due to an incorrect switch setting which misconfigured the guidance computer; there was no problem with the ascent engine itself.

    On Apollo 11, while moving around in the cabin, Aldrin accidentally broke off the handle on the engine arm switch which enables the ascent engine.  He was able to turn on the switch with a felt-tip pen.  If the switch could not have been activated, a software patch to the guidance computer code would have enabled firing the engine.  Since the ascent engine had been tested three times before, there was high confidence it would work.  However, if it failed, the astronauts would have been stranded on the Moon.  In Apollo 9 and 10, if the ascent engine had failed, the astronaut in the command/service module could have rendezvoused with the LM and rescued its crew.

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  8. I may be quibbling but from what I heard the engine that went to the moon was not tested before it went there. That if there was a flaw it would be found out on the moon surface. The type of engine was tested but not that engine.

    Thank you for all the great information.

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  9. Here is a project I did in 2007, “The Relativity of Simultaneity”, in which I time-shifted Apollo 11 audio from Mission Control, radio transmissions from the LM, and the audio tape recorder in the LM cabin, to reconstruct what Armstrong and Aldrin heard on-board during the landing,  It explains the long pause after Armstrong says “Houston” and before continuing “Tranquility Base…”.

    I was, to my knowledge, when I created this audio, only the third person to have heard this audio as the Eagle crew would have heard it.

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  10. 10 Cents:
    I may be quibbling but from what I heard the engine that went to the moon was not tested before it went there. That if there was a flaw it would be found out on the moon surface. The type of engine was tested but not that engine.

    This is correct.  The Ascent Propulsion System [PDF] engine used an ablatively-cooled combustion chamber and nozzle.  As the engine burns, the ablator chars and carries away heat which would otherwise cause a burn-through.  Sufficient ablator is applied to cool the engine through a maximum-length burn.  Because the ablator is consumed by a burn, the engine would have to be extensively refurbished after a test firing and would be, essentially, a new untested engine.  Consequently, no test firings were performed.  The extreme simplicity of the engine (pressure-fed, hypergolic propellants that required no ignition system, and redundant valves and control components) was felt to provide adequate reliability without a test firing.

    The flight tests on Apollo 5, 9, and 10 were to, among other objectives, qualify the operation of the engine design in space.

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