Apollo 14 Flight Crew Guidance & Navigation G&N Dictionary

13 responses to “Apollo 14 Flight Crew Guidance & Navigation G&N Dictionary”

1. 

   jurvetson

   Nov 24, 2011 at 1:12 am

   Now signed by Ed MitchellWhy Pink?
   The question can be clearly seen on this early page. It’s not an aversion to cuties, but a color reserved for contingency pages:
   Notice the programs P, Nouns N and Verbs V to be punched into the DSKY in order.
   P0 idles the computer so it can just run background processes.
   P21 does ground track determination (knowing the spacecraft’s location and trajectory, it would display where they will be at a given time in the future)
   P52 does platform realignment off of star sightings (using the optical telescope when in the LM)
   P27 allows direct data entry into the LM’s Guidance Computer
   After these "reasonableness checks" P6 puts the computer in a power-saving standby mode, maintaining mission time. To shut it off completely required a circuit breaker pull, like with HAL. =)

   The following images are clickable for full size viewing.
   Various corrections and changes by hand… within a month of launch:
   Bugger Word?… There are many test runs with this page for the PIPA x,y,z offsets. The PIPA’s (Pulsed Integrating Pendulous Accelerometers) are one of the two major components of the IMU. Three of these devices measure accelerating forces on the spacecraft in all three axis, and by integrating these accelerations over time, are able to calculate the resultant velocity changes. Like the gimbal assembly, PIPA’s have a tendency to drift from absolute accuracy. Since this drift is rather well understood, and much can be determined in pre-flight qualification testing, the computer is instructed to make allowances for this drift by applying a small bias against the information provided by the PIPA’s. As on all flights, engineers on the ground are continually evaluating the performance of the PIPA’s against its previous history, and if there is a discrepancy, recommend changes in the bias value used by the computer.
   
   The ORDEAL is a kludge in the user interface. It is a box added during flight to make the FDAI 8-ball show attitude with respect to the ground.

   Here you can see the 5-digit data field from the DSKY and the math with decimal point location in odd places:
   The P30 LM Maneuver. With comments on 5 second vs 26 second burn times. P30 is the external delta-v program takes the time of ignition and velocity change that is desired as the inputs and calculates the other parameters associated with the burn. This burn would be used in the event of an emergency. It would be fired 5 hours before the planned insertion into lunar orbit. At that point, Apollo 14 would be so near the Moon that it would be easier to allow Apollo 14 to continue and fly around the Moon for a free return trajectory. The burn would be made with the SPS engine under the control of the Guidance and Navigation System. Noun 33 at the top is the time of ignition in Ground Elapsed Time (GET). Noun 81 is the next one, with change in velocity in three dimensions. Noun 42 has Ha and Hp, the height at apogee and perigee:
   
   750+14 = 764 written out.. just to make sure… =)

   PAD pages with tables like this were used throughout the mission.

   P.S. Here are other Apollo 14 artifacts, such as the CM Docking ring.

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2. 

   Pieces of Eye

   Nov 24, 2011 at 5:16 am

   Can they check the Doppler shifts of the spacecrafts telemetry signal and use it as a PIPA check?

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3. 

   solerena

   Nov 24, 2011 at 5:37 am

   Interesting and looks so antique with these letters, math and colors…

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4. 

   liu_yi_feng

   Nov 24, 2011 at 6:20 am

   great job! , Happy Thanksgiving 🙂 !

   Reply
5. 

   jurvetson

   Nov 24, 2011 at 7:03 am

   [http://www.flickr.com/photos/physicsman] – Ground Doppler, intertial calculus and star sightings were used for triple redundancy.

   The history of the Doppler decision here is fascinating… Here are some passages I just read from Woods’ How Apollo Flew to the Moon, 2011:

   “In the early days, Apollo had become a part of the Cold War. There were serious concerns that the Soviets might try to interfere with Apollo flights, perhaps by jamming radio transmissions, therefore it was decided that the guidance and navigation system should be completely autonomous. Once dispatched to the moon, the crew should be able to navigate, conduct their mission and return home entirely without assistance from the ground. This philosophy drove the design of the spacecraft’s guidance systems by the Instrumentation Laboratory of MIT. However, by the time Apollo was ready to fly a lot had changed.

   NASA decided that ground-based techniques would be the prime means of determining the state vector (location and speed). The crew would still make their own separate determination, but only as a backup to be used in case of emergencies.” (p.156.)

   Experience from remote control of Ranger probes, Surveyor landers and Lunar Orbiters in the mid 60’s gave them confidence in ground control using Doppler shift for velocity and time delay of code streams for distance.

   “Ground stations supporting the Apollo program had some of the most accurate frequency standards available at the time.” (p.158)

   They were too heavy and power hungry for space, so they beamed a 2.1064 Ghz carrier to the spacecraft, carrying data and voice. The spacecraft multiplied it by 240/221 and used that higher frequency as its carrier for the downlink.

   “When received by the ground station, the precise frequency of the downlink was measured and compared to the uplink. This was a very powerful system because it measured Doppler shift over both the up and down legs of the signal’s journey, doubling the sensitivity of the system to the point where it could even detect the velocity change caused by the minuscule thrust that was generated when the crew dumped their urine overboard.” (p.158)

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6. 

   Pieces of Eye

   Nov 24, 2011 at 9:35 am

   Very cool. Every time I learn a little more about the space program I’m inspired by how clever it is and was.

   I imagine the conversation with ground control that determined the urine dump thrust was amusing (unless it was pre-calculated 🙂 ).

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7. 

   strange_wax

   Nov 24, 2011 at 4:13 pm

   I particularly like the "Wait 15 sec before POO" 😉

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8. 

   jurvetson

   Nov 24, 2011 at 5:48 pm

   Oh that’s hilarious! Just s nudge to my referential frame and now the first line of the pink page reads:

   Go to poo
   Wait 15 sec before poo.
   (a stream of verbs)
   Simultaneously mark reject.

   P.S. I made the double-pages above clickable so the handwritten scribbles can be seen.

   The complexity this in-flight instruction manual for the DSKY…. well, um, as the first IC-based computer, it certainly predates the Apple philosophy of no manual needed… =)

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9. 

   linademartinez

   Nov 24, 2011 at 6:28 pm

   One of my favorite displays at the National Air and Space Museum in Washington.

   

   Imagine being able to leaf through those documents. Wow 🙂

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10. 

    Rafe

    Nov 24, 2011 at 6:40 pm

    I like the "Reasonableness Check" on the first image. Reminder for the astros to do a gut-check or what?

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11. 

    Bill York

    Nov 24, 2011 at 7:59 pm

    Thanks, Steve. Awesome detail. Imagine this book in the context of being 200,000 miles out into space and how much you are relying on it to complete your mission and return home alive.

    Reply
12. 

    jurvetson

    Oct 8, 2012 at 2:37 am

    yeah… and here is what Ed Mitchell was also thinking…

    

    Reply
13. 

    jurvetson

    Feb 6, 2021 at 12:49 am

    Today is the 50th anniversary of Ed’s first steps on the moon.

    I spoke with him and he signed this book

    Reply