October 5th 2020 - Snoopy Celebration

savio.79

Random points?
Am I wrong or were the famous 14 seconds necessary to correct the trajectory of the module?
And am I wrong or the instruments were off, they could only use the clock?
And am I wrong or, since the instruments were off, they could only rely on sight to align the trajectory with the Earth (I'm not an expert but I remember something like that in the movie LOL).
So, here we have a watch; you push the start button and then, you stop it at 14 seconds; then you turn around the watch and see the back, finding the module aligned with the Earth.
If so, it doesn't seem very random to me.

(if I remember the movie wrong, I apologize) LOL

H hb8745

I'm not sure, I didn't see the movie, maybe I'll have to give it a watch.

Instruments definitely weren't off, they just didn't use computer assist for the DPS burn

I've listened to the actual audio recording and read the logs. Honestly didn't seem like thatttt big of a deal compared to some of the other midcourse corrections that they needed to make. I don't think for this portion they were able to have a visual of the earth for alignment out of the module, and in either case the rocket angles were locked for the burn. I'm not an expert so I maybe wrong, but I don't think for this type of correction, seeing the earth would have any impact on their actions. I would think that they just do the math or someone from the ground does the math and relays, rather than aligning by sight at 150k miles away...

Imagine if they had tried to use this "feature" to time the actual event. I'd be sweating bullets for the 8 seconds that snoopy was behind the moon, wondering if I had actually started the time.

rominvicta

🍿 I got myself in two lists in two separate countries. Hopefully I will succeed at least in one of them. One is OB and as of them will be getting it within this year. Second one is an AD and they say next year second quarter.

EricCsN

u are hoarding

rominvicta

That would be The Decade Watch for me! I can’t allow myself to miss it!😀

EricCsN

I think they had to shutdown everything they had to conserve power save for the very absolute minimum to preserve life and the barest communication with earth. you also cant relay when to start and stop to them (as the distance from earth to the module is large so there is a time delay between sending the signals for this from earth and them astronauts on board receiving and reacting to it - wont be accurate)

H hb8745

Well the oxygen tank explosion meant they had to adjust the re-entry angle from free-return in order to make the entry more shallow to speed up the return before they ran out of power. So yes they did power a lot of things down, but I don't think core instrumentation needed for the correction was one of them.

By relay from the ground I meant the math and calc for the burn - obviously they're not relaying the actual signal for the engine timing lmao. They probably just did the calculation on board and then confirmed with Houston.

My point was that they're not just flying by visuals/feel. Basically just a lot of geometry, physics, and math. Lot of people on the ground providing support and crunching the numbers and doing the trajectory planning as well. If anything, checking the visuals would be after the fact and would need to perpendicular to the stars, not necessarily the earth. If you're not seeing stars then you've already messed up pretty badly.

EricCsN

No revisionist conjectures needed. Here is the actual transcript from nasa archives. Note what it says” before that however they will have to adjust their trajectory at least once more, without the use of the GUIDANCE COMPUTER in the POWERED DOWN lunar module...” and you can read the transcript where it says under lapsed time 104:35:53 ...time of ignition ... in this case since they are not using the computer to control the burn. It is simply used as a familiar term in filling the PAD. Timing will be performed manually”
https://history.nasa.gov/afj/ap13fj/19day5-themanualcoursecorrection.html

H hb8745

Honestly I'm not sure if you have reading comprehension issues or my writing is that unclear, but what are you insinuating here as my "revisionist conjecture?" I never said they were using the computer to control the burn, and I never disputed that it was a DPS manual engine burn. All I said is that they were using the data given by the onboard instrumentation to calculate the burn times using math / geometry.

How do you think they came up with the 15 second figure? You think they pulled it out of their ass or just aimed visually? There's many inputs and variables that went into the burn and I guarantee you they were monitoring other stats besides just the time elapsed.

dstfno

I've enquired with my local AD (in Spain) and they called Omega to verify when (and if at all) they could expect the Snoopy 3. The answer was that it should come in in the later half of Q1/2021. I was given the option to order one, without deposit and the ability to decide if I actually want to buy it after trying it on.

EricCsN

I'm not sure, I didn't see the movie, maybe I'll have to give it a watch.

Instruments definitely weren't off, they just didn't use computer assist for the DPS burn

I've listened to the actual audio recording and read the logs. Honestly didn't seem like thatttt big of a deal compared to some of the other midcourse corrections that they needed to make.
(if you have done that with actual audio recording and reading of the logs, it suggest you have provided to the readers here an accurate account . But your conclusion that it was not a big deal with the way you wrote 'thatttt'. Yet this is not the case, from the records they had only a narrow 2 degrees angle to meet with that most critical 14 seconds timing of ignition being significantly important of the trajectory of getting this angle right.)


I don't think for this portion they were able to have a visual of the earth for alignment out of the module, and in either case the rocket angles were locked for the burn. I'm not an expert so I maybe wrong, but I don't think for this type of correction, seeing the earth would have any impact on their actions.
(WRONG. they were piloting the spacecraft visually with the earth in sight - one was controlling the left and right (yaw), another was with the up and down (pitch) while the third was timing with the speedmaster)

I would think that they just do the math or someone from the ground does the math and relays, rather than aligning by sight at 150k miles away...
(the maths was done from the ground, but the astronauts had to execute it because of the distress state of the spacecraft. Moreover the spacecraft was not supposed to be joined together - landing module and command module - on the way home (the landing module was supposed to be detached on the the moon - which changed the dynamics and affected the controls )


Imagine if they had tried to use this "feature" to time the actual event. I'd be sweating bullets for the 8 seconds that snoopy was behind the moon, wondering if I had actually started the time.

(it was all that they got - systems have been damaged - they had no choice.)

Soulcreek

Good for you, hope u can get it and you like it. And like the mission, hopefully your post has put us back on course to discuss the main topic of the thread: the watch

Soulcreek

Good for you, hope u can get it and you like it. And like the mission, hopefully your post has put us back on course to discuss the main topic of the thread: the watch

H hb8745

It wasn't a that big of a deal. The real big deal was the PC+2 burn that allowed them to splashdown in the south pacific. That burn had a much tighter tolerance, and was extremely accurate. How big of a deal do you think MCC 5 was if they didn't even bother to power up PGNS? They even initiated earlier than scheduled because the timing wasn't that critical. MCC 5 and 7 were just to steepen the EI angles slightly, but the PC+2 burn was the one that really saved them imo.