Wednesday, July 20, 2022


 Originally posted on July 19, 2019, the 50 year anniversary of what may be the high water mark of humanity and all we can accomplish, there is value in remembering how great we can be:

The fascinating part of the historic Apollo 11 landing on the moon (50 years ago today) is the handling of the 1202 and 1201 alarms during the decent of the Eagle to the lunar surface.

P63: Some Apollo-nerd stuff that you only get here: The Eagle's computer had three programs to run from the time it undocked to landing. The first was P63: which controlled Eagle from undocking while it was still in orbit,  to powered-descent -the landing. P63 controlled the attitude (pitch and yaw) of Eagle and ran the burn of the engine which took Eagle out of orbit and into a controlled descent to the lunar surface. PDI (powered-descent initiation) occurred about 500 kilometers east of the landing site and 12 minutes to landing. The first go-no-go from Houston after the go-no-go for undocking was for PDI. 

P64: When the Eagle was three minutes from landing and 7 kilometers from the site, the computer ran P64. The P64 program pitched the Eagle forward and gave Armstrong a view of the lunar surface so he could check for landmarks. At this point the computer is telling the astronauts and Houston where it intends to land. If you listen to the raw landing tapes, the guidance officer in Houston is indicating that they are headed for a spot longer down-range than anticipated. 

P66: When the Eagle is 600 meters from the landing site, Armstrong activates P66 in which he and the computer share the throttle while Armstrong alone controls the pitch and yaw. 
Somewhere along the way a switch was flipped powering on the rendezvous radar that was supposed to be off. The rendezvous radar began feeding more information to the computer than it was designed to handle at exactly the wrong time- during the dangerous descent phase. How Armstrong and NASA handled this critical error is the stuff legends are made of.

As PDI begins, Houston immediately loses signal and data from Eagle, prompting a call to Collins in Colombia to tell Aldrin to re-aim an antenna. Meanwhile Neil Armstrong has several issues to contend with, including no communication with the men who are supposed to guide him. 

As the Eagle descended Armstrong began to realize that the guidance computer was taking him farther down range then it was supposed to and was putting the Eagle into a crater. The Eagle has two guidance systems: PGNS (pings) is the main system, and AGS is the back-up. Both Houston and Aldrin  are monitoring both systems and comparing their data to see if it matches as the Eagle descends towards history and the Moon. 

As  P63 turns the Eagle around so that now it's Engine is facing the lunar surface, the landing radar and other radar (that's supposed to be off) both lock on to the lunar surface. The computer is overloaded with data, and now come the words that almost ended the mission: "1202...1202 alarm."  Eagle is 33,500 feet above the surface of the moon. 

In the simulator   Armstrong and Aldrin had practiced with several different scenarios, including the loss of various functions of the Eagle, wrong indicators, loss of communication, and the like. But in the thousands of hours of training, they had never encountered a 1202 alarm.

Here is what happened on the ground in Houston and their success showed why NASA was able to achieve the extraordinary moon landing:

Gene Kranz was the flight director, later responsible for the saying "failure is not an option". Kranz was the one who made the final decision to allow the Eagle to land. 
Jack Garman was an engineer and part of the team working on the computers and the landing guidance system of the Eagle. At a meeting several weeks before the landing,  Kranz told Garman to write down every possible alarm and the response to the alarm.
Steve Bales was the guidance officer who was one of the men responsible to answer Kranz during various "Go-No-Go" calls when Houston had to tell Armstrong if he could continue to land.
Astronaut Charlie Duke was "cap-com" the man responsible for speaking directly to Aldrin and Armstrong. 

Several seconds after the 1202 alarm, Armstrong having heard nothing from Houston, asked "give us a reading on that 1202 alarm."  When you listen to Armstrong, there is some uncertainty in his voice. He is about 30,000 feet above the surface of the moon and less than seven and half minutes from landing. He is looking for a place to land, watching his fuel, working on the high-gain antenna issue, and now an alarm that he does not recognize is going off which may cause the mission to be aborted. 

Meanwhile in Houston, when the alarm went off, Kranz was looking towards his guidance officer Bales or anyone else who knew what the alarm was. Nobody knew. There were blank stares all around as Krantz's landing team started scrambling though massive three-ring binders looking for what a 1202 alarm was. Eventually Krantz asked Bales and Bales called over to a back room where there were dozen of engineers One of them- Jack Garman - knew what the alarm meant.  

Apollo 11's computer's were rudimentary. The landing radars started giving the computer more data then it could handle. When this occurred the computer had a line of programing to tell it to prioritize its work and to trigger a 1202 alarm to let Houston and the Eagle know what it was doing. Essentially the computer was rebooting without shutting down. If the computer had shut down, Kranz would have ordered an abort. 

Garman reasoned that as long as the alarm didn't continually repeat, which would mean the computer was in a non-recoverable loop, that they were "go" on the alarm. Garman told Bales. Bales told Kranz. Kranz told Duke and Duke told Armstrong. 

There was another 1202 alarm and then a 1201 alarm at 27,000 feet above the surface. Aldrin tells Houston about why he thinks the alarm is occurring. Meanwhile,  Garman quickly told Bales that the 1201 alarm was the same type of alarm as the 1202 and that they were "go" on that. 

Armstrong never doubted what Duke was telling him. Kranz had faith in Bales and Bales knew Garman knew the landing computer software better than anyone. 

At about 9 minutes into the landing, and 5200 feet about the surface the computer switched to P64 and the program pitches Eagle over so that the attitude of the Eagle is more upright and it begins to descend in the same attitude that it will have upon landing. Armstrong is now looking at the surface so he can find a place to land.  Kranz quickly runs through a "go-no-go" for landing and Retro (the controller monitoring the engines), FIDO (flight dynamics), ECOM (electrical, environmental and consumables), Guidance, and the flight surgeon all give Kranz an enthusiastic "GO!" for landing which Charlie Duke relays to Aldrin and Armstrong. At 3,000 feet they get another 1201 alarm, but they are quickly told they are "go on that alarm" and the descent continues. In another minute, at 1300 feet they get another 1202 alarm, but they are still go to land. 

 At 600 feet the P64 program is steering the Eagle toward a sea of boulders and craters. Armstrong decided to switch to the P66 program and manually take control of Eagle. He began to use the thrusters to navigate the Eagle past a large crater and then looked for a relatively flat area to set his craft down on, all the while monitoring an ever dwindling fuel supply and a host of other issues. They are 300 feet from the surface and Aldrin tells Armstrong  that he is "pegged at horizontal velocity" meaning they are going forward at the top speed on the indicator. At 250 feet Armstrong is now slowing the forward velocity. He sees a landmark he recognizes: "Little West Crater" and he pilots Eagle just past it where he sees a relatively smooth surface to land. The forward velocity has slowed from 50 feet/second to 19 feet/second. At 175 feet they have 94 seconds to land or they will get a "fuel-bingo" call from Houston and will have to abort. 

The Eagle had one chance to land on the moon. If the landing was aborted, they activated the ascent engine, flew back to Michael Collins in Colombia, and headed back to earth having failed in their attempt to land. There were no second chances on this flight. 

At 100 feet they have 75 seconds to land. Armstrong is demonstrating why he was chosen for this mission- he is at the top of his game and pulling off the greatest landing in the history of aviation- and one of the most difficult and dangerous to boot. At 75 feet their velocity has slowed to six feet forward/second. At 60 feet Charlie Duke calls out "sixty seconds": they have a minute of fuel left to land. At 20 feet Charlie Duke calls out "thirty seconds". There is almost no fuel left to land. 

With seventeen seconds of fuel remaining Aldrin calls out "contact light": a 1.5 meter probe below Eagle has touched the surface.  

The team worked. The system worked, and Armstrong landed the Eagle with 17 seconds of fuel remaining. 

The first words spoken by a human being on another celestial body belonged to Buzz Aldrin: "Contact light. Ok. Engine stop. ACA out of descent. Mode control both auto descent engine command override off. Engine arm off. 413 is in.

Hardly memorable or historic words, but before Armstrong tells the world that from Tranquility Base "The Eagle has landed" Aldrin had a checklist he needed to run through to make sure the descent engines were shut down and the abort-ascent  engine couldn't be accidentally triggered. 

Charlie Duke responds "we copy you down Eagle".
Armstrong says "The Eagle has landed" and Duke responds that there were a bunch of guys about to turn blue but were breathing again. This is in response to the fact that with less than 30 seconds of fuel, the Eagle had not landed and everyone in mission control was holding their breath. 

A half a million people worked on some part of the Apollo program. But on July 20, 1969, it was Kranz, Steve Bales, and Jack Garman who gave the go ahead to Armstrong and Aldrin to continue the landing in the face of 1202 and 1201 alarms.

In these days of seemingly unsolvable problems- wars, global warming, plastic choking the ocean, no reservations at the Pickle Ball court for weeks,  the Apollo program and the (mostly men) of Apollo 11 remind is we as human beings can do great great things if we all work together for a common goal. 

(Although the 9 am Saturday spot on the Pickle Ball court is booked solid through the end of the year).


Anonymous said...

This is so brilliantly written and so incredible to read. Thank you Rumpole.

Anonymous said...

Lol you believe that shit? Evidence is clear that moon "landing" was done on a soundstage in Houston.

Rumpole said...

Actually you’re right. Sort of. It was done on a soundstage in Africa by none other than a young Barack Obama where he was born and lived. And the raw video was then sent to a company in Venezuela where it was edited and processed by the same company which 51 years later used satellites to hack voting machines in the last presidential election. The company is run by Elvis. They keep a Bigfoot in a cage as a mascot. It is funded by the money the CIA earned for killing President Kennedy.

I mean if you’re gonna expose a coverup then do it right. Btw you don’t need to wear the tinfoil on your head when posting comments in the blog. The chip in the vaccine you got allows me to read your thoughts now without resorting to the 5G hack.
Be well and take your meds mi amigo.

Anonymous said...

It's fine Rump if you want to go thru life as a sheep.

Anonymous said...

Brilliant retort

Anonymous said...

Hey Mr/Ms 10: 36 am...

I bet you voted for Trump and love Ronny D. I bet you are old, white and a racist or maybe you are Marjorie Taylor Green. I bet you think Homosexuality should result on the death penalty. I bet you hate gay marriage but, are divorced at least twice. I bet you have only a high school diploma.

In other words, I bet you fall for all that crap.

Anonymous said...

To the guy who thinks the moon landing was staged, I ask you this? Was the holocaust staged too?

Anonymous said...

Rumpole, from what I hear the modern unsolvable problems list should include software glitches.

Anonymous said...

Faking the moon landing in 1969 would have been harder and more expensive than actually going to the moon.


Anonymous said...

Gene Kranz never actually said the words "failure is not an option." It was a dramatized phrase improvised by the screenwriters of "Apollo 13" to sum up the ethos of the Mission Control crew.

Failure is Not an Option is a phrase associated with Gene Kranz and the Apollo 13 Moon landing mission. Although Kranz is often attributed with having spoken those words during the mission, he did not. The origin of the phrase is from the preparation for the 1995 film Apollo 13 according to FDO Flight Controller Jerry Bostick:

"In preparation for the movie, the script writers, Al Reinert and Bill Broyles, came down to Clear Lake to interview me on "What are the people in Mission Control really like?" One of their questions was "Weren't there times when everybody, or at least a few people, just panicked?" My answer was "No, when bad things happened, we just calmly laid out all the options, and failure was not one of them." ... I immediately sensed that Bill Broyles wanted to leave and assumed that he was bored with the interview. Only months later did I learn that when they got in their car to leave, he started screaming, "That's it! That's the tag line for the whole movie, Failure is not an option."


Anonymous said...

And for a few hours leading up to Armstrong's one small step, the world was interested in space travel. Then the magic faded and space travel became yesterday's news. NASA had to constantly beg politicians to fund any more moon missions.

When Apollo 13 launched, all the TV networks declined to air the crew broadcast. It was only when the explosion happened and the crew was in mortal danger that America became interested again. But even that didn't stop the inevitable loss of interest in space. It's only when disasters and tragedies happen, like Challenger and Columbia, that people seem to regain some momentary interest in space travel.

Rumpole said...

10:36. I believe in the mon landings. All of them. I believe Biden won and I believe in global war,Inv and wearing masks helps stop the spread of COVID 19. Baaaaaaa

Anonymous said...

As the "Ice Man" would say, "failure is not an option".

Anonymous said...


who won the presidency fair and square in 2000 and in 2016?

Rumpole said...

In 2000- Ralph Nader and in 2016 Hillary Clinton got the most votes, so she won right?

Anonymous said...

Rumpole with another riveting account of a historical event.

Anonymous said...

Have you seen the Tessa Tylman signs? There should be no doubt the name change was solely to mislead the voters. The sign is basically just the newly changed last name in large bold letters. She may not be smart, but she knows how to get votes from one of the better judges this county has. And Blunstein apparently doesn’t care about his DoD violations.

Phil Maniatty said...

On a lighter note, didn't the crew bring a recording of Sinatra's, "Fly Me To The Moon," with the Count Basie band to play upon landing?

Anonymous said...

Watch for all mankind on apple. It is a really great take on the space race with alternate history.

Anonymous said...

And we haven't gone back... Why?

Anonymous said...

Lol u know why.