Astronaut Gene Cernan passed away, last man to walk on the moon

WBA Consulting

Sad to hear this today. Very few recognize the name and I in fact only learned it a few months ago after watching an excellent documentary about him on Netflix. My wife, daughter, and I were glued to the tv watching it. He was a remarkable man and deserves to be remembered as much as any other Apollo astronaut.
https://www.nasa.gov/astronautprofiles/cernan

https://dvd.netflix.com/Movie/The-Last-Man-on-the-Moon/80087933

http://www.imdb.com/title/tt3219604/
When a documentary gets 7.4 out of 10, you know it's good!

Publison

Yup. Saw that on the news at 4:00 AM. Last man to walk on the moon.

RS_Jim

Makes those of us who watched the first moon landing feel old!
Jim

Alexander (Sandy) Hapgood

One of his life experiences was walking on the moon. That's pretty good.

Heater.

Yep. That's pretty good. Those guys were amazing.

I suspect that was the peak of human achievement.

WBA Consulting

Heater. wrote: »

I suspect that was the peak of human achievement.

In many ways, I agree. I am currently reading "Digital Apollo" which is an excellent compilation of all of the details regarding man and machine throughout the Apollo project. I am still amazed at the engineering feats that were made with the available technology in that timeframe. I wasn't even a year old when the last Apollo mission ended, so I don't remember any of it, but I could read and watch anything and everything about the landings.

Heater.

I recently discovered an amazing thing.

When the first men on the moon were a few thousand feet from the surface their LM navigation and guidance computer started blasting out "1202" and "1201" program alarms.

Mission control had to decide, pretty damn quick, whether to abort a landing attempt or not.

A young software engineer there chirped up and basically said "I know what that error is. Ignore it". So they did and all went well.

For decades I was amazed that anyone knew the software so well as to be able to make that call so quickly and confidently. Which is pretty brave as he was hardly more than 20 years old.

Turns out that when the error codes were reported back to mission control nobody knew what they were. That young guy had previously printed out all possible error codes and there meanings and stuck paper to the side of his terminal screen! So he knew.

Sorry I don't recall that young guys name. Or provide a link to the documentary where he tells that tale.

Sapphire

No more cogs available

https://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html

Heater.

Yes. That is the story.

But notice how it says " The NASA guys in the MOCR knew - because MIT had extensively tested the restart capability - that the mission could go forward." As if they all knew immediately and could confidently say go ahead.

Well, I recently found a documentary video on Youtube where they talk to the software engineers involved. The story I got from that is that nobody had a clue what was going on. Or if it was safe or not. They had never seen that error before! Only one young guy, who happened to have taken the trouble to trawl through the source and scribble down all the possible error codes for his own use.

Whish I could find that vid again to link here.

Tor

That error message was about overloading the capacity of the computer, the MIT engineers thought that when landing you would use the landing radar, and when rendezvousing with the command module you would use the rendezvous radar. Not both at the same time. But Buzz Aldrin wanted to (of course, in hindsight) use both at the same time - in case they had to abort the landing, he wanted to track the command module so that he *could* rendezvous! (Or possibly it was just to keep it on, so that it wouldn't be necessary to wait for it to warm up, in that case).
That was a bit too much for the little computer.

That's how I remember Buzz Aldrin explaining it in an interview I watched. In reality it was (as always) slightly more complicated. I found a very interesting document on the net: http://www.doneyles.com/LM/Tales.html
Many things are explained there, e.g. another issue which contributed to the problem: "An uncorrected problem in the rendezvous radar interface stole approximately 13% of the computer's duty cycle". So with the rendezvous radar active, then when the landing radar locked, the CPU load went above capacity, and it didn't have enough time to perform all its tasks and it bailed out with 1201 or 1202. But the software restart just flushed the lowest-priority jobs that had accumulated, so all went well.

About the real-time incident itself:

"Then we heard the words "program alarm". In Cambridge we looked at each other. Onboard, Aldrin saw the PROG light go on and the display switch back to Verb 06 Noun 63. He quickly keyed in Verb 5 Noun 9. Alarm code 1202 appeared on the DSKY. This was an alarm issued when the computer was overloaded — when it had more work to do than it had time for. In Cambridge the word went around, "Executive alarm, no core sets". Then Armstrong said, with an edge, "Give us a reading on the 1202 program alarm"[10].

From here events moved very quickly, too fast for us to have any input from Cambridge. It was up to Mission Control in Houston. The story of what happened there has often been told — how it fell to a 26-year-old mission control guidance officer named Steve Bales to say "go" or "abort". Bales had participated in a recent review of LGC alarms that had deemed 1202 a "go" unless it occurred too often or the trajectory deviated. He was supported by Jack Garman of NASA and Russ Larson of MIT in the back room. Garman said, "go". Larson gave a thumbs-up. (He later said he was too scared to form words.) So Bales answered, "go", Flight Director Gene Krantz said "go", and capsule communicator Charlie Duke passed it up to the crew. At MIT, where we realized that something mysterious was draining time from the computer, we were barely breathing."

Heater.

Also interesting was another vid I stumbled across last year where somebody was giving a presentation about the development of the Apollo guidance attitude control and guidance system. Seems they used a lot of maths they found published by Russian academics.

Dave Hein

Tor wrote: »

That error message was about overloading the capacity of the computer, the MIT engineers thought that when landing you would use the landing radar, and when rendezvousing with the command module you would use the rendezvous radar. Not both at the same time. But Buzz Aldrin wanted to (of course, in hindsight) use both at the same time - in case they had to abort the landing, he wanted to track the command module so that he *could* rendezvous! (Or possibly it was just to keep it on, so that it wouldn't be necessary to wait for it to warm up, in that case).

Buzz Aldrin is often blamed for leaving the rendezvous radar on. However, the description of the events at https://www.hq.nasa.gov/alsj/a11/a11.1201-fm.html indicates that the radar was left on because the landing instructions said to leave it on.

Here's a quote from the website:

I rushed upstairs and suggested we look at the telemetry data. Some of the M.I.T engineers found the telemetry print out, found the correct 16-bit packed word, found the correct bit, and... yikes!!!, the bit was ON. Why was it on? It had to be set in that position by an astronaut. We looked at the 4 inch thick book of astronaut procedures and there it was -- they were supposed to put in on (in the AUTO position) prior to Descent. The computer had been looking for radar data. If the astronauts were trained this way, why had this effort never shown during training sessions? (I later found out that such training was for procedures only and the Switch was never connected to a real computer.)

Tor

I've never heard that he was "blamed" for it.. any blame would be with any who didn't think it shouldn't be on. If you read the paper I linked to, it explains the "auto" setting issue.
Buzz Aldrin was called Doctor Rendezvous by the way.. he knew his stuff (and has a PhD). In the interview I watched he said that he was somewhat shunned at parties because he would corner people and only talk about rendezvous and trajectories.

Dave Hein

I've seen a few accounts that blamed Buzz Aldrin for causing the alarms. They thought that he was too concerned about rendezvousing with the command module in case they had to abort the landing. However, it appears that he was just following the procedure that had been developed by NASA.

MikeDYur

Sad to here about Gene Cernan, we have lost a few of our space pioneers in recent year's. John Glenn and Neil Armstrong all lived a good long life, there job could have shortened it at any time. Buzz Aldrin had a close call just trying to prove something to himself.

Publison

And it's Buzz Aldrin's birthday today.

https://en.wikipedia.org/wiki/Buzz_Aldrin

Heater.

Happy birthday Buzz.

You guys were gods to us young kids.

You still are.