Science Channel - Moon Machines

[cljohnston]

I'm just watching the Science Channel's 6-part documentary series from 2008, Moon Machines, by the makers of In the Shadow of the Moon.

[ame="http://en.wikipedia.org/wiki/Moon_Machines"]Moon Machines - Wikipedia[/ame]

Like Shadow, it utilizes never/rarely-seen footage behind the manufacturing process, but in far greater technical detail than the mainstream audience could tolerate.
In other words: It's what we Orbiteers have always dreamed of!



However, I'm up to Part 2, on the Command Module, and, sadly, they've made a bit of a goof when describing the systems of the Service Module...

Narrator: "The clever idea behind the fuel cell was to use the same hydrogen and oxygen gases which powered the spacecraft's rocket engine. In the rocket, the gases reacted together, creating heat and pressure to push the spacecraft forward. But in the more controlled environment of the fuel cell, the same reaction could produce electricity."

*cough*Hypergolics*cough*

 

[Keatah]

How is that a goof?

 

[T.Neo]

"The clever idea behind the fuel cell was to use the same hydrogen and oxygen gases which powered the spacecraft's rocket engine. In the rocket, the gases reacted together, creating heat and pressure to push the spacecraft forward. But in the more controlled environment of the fuel cell, the same reaction could produce electricity."

Hydrogen and Oxygen were the propellants used by the upper stages of the launch vehicle though, including the S-IVB which actually propelled the CSM/LM stack to the Moon.

Not a total goof, as hydrolox was used for propulsion, but just not on the CSM itself, in which the fuel cells were located.

 

[cljohnston]

Hydrogen and Oxygen were the propellants used by the upper stages of the launch vehicle though, including the S-IVB which actually propelled the CSM/LM stack to the Moon.

Not a total goof, as hydrolox was used for propulsion, but just not on the CSM itself, in which the fuel cells were located.

Right, but the episode was dealing solely with the Command Module, with a smaller emphasis on the Service Module, and the word 'hypergolic' was never mentioned once, so I consider that a major omission, considering all the other awesome detail they've put into it.

 

[datubaman]

That's because the hydrogen and oxygen aren't hypergolic. Hypergolics are fuels that combust instantaneously upon contact with each other, without the need for any external source of ignition. However, they tend to be very corrosive and very toxic, meaning that they had to be handled with care, and lots of it. However, since they do react on contact, they are very reliable, meaning that a well built engine will ignite easier and more reliably than ordinary, non-hypergolic rockets. This is the main reason that Grumman chose a Hypergolic rocket to propel the LEM's ascent stage.

 

[Keatah]

Isn't a hypergolic system much simpler and lighter weight? Less parts, no ignition spark plug?

 

[T.Neo]

Also, fewer insulation problems and thus less mass, complexity and danger due to the containment of a cryogenic fluid, not to mention storability issues.

 

[cljohnston]

That's because the hydrogen and oxygen aren't hypergolic. Hypergolics are fuels that combust instantaneously upon contact with each other, without the need for any external source of ignition. However, they tend to be very corrosive and very toxic, meaning that they had to be handled with care, and lots of it. However, since they do react on contact, they are very reliable, meaning that a well built engine will ignite easier and more reliably than ordinary, non-hypergolic rockets. This is the main reason that Grumman chose a Hypergolic rocket to propel the LEM's ascent stage.

Whuh? Anybody listening to what I'm saying?
I'm talking about the SPS engine on the Service Module, which ran on hypergolics.
The documentary said that the fuel cells used the same fuel as the engine on the Service Module, which is simply wrong.
The only reason I even mentioned it is because everything else in the series is so amazingly well researched, I'm just shocked that they would let such a glaring error stay in.

I'm not the only one who noticed, either. Here's a post from a similar thread on the NASA Spaceflight forum a couple years ago (emphasis mine)...

Thorny
Re: Science Channel's "Moon Machines"
« Reply #9 on: 07/07/2008 05:47 PM »
There were a few errors in the Command Module episode. The announcer's mispronunciation of Schirra ("Sheer-a" instead of "Sure-rah") was unfortunate, as was Borman being misidentified as Lovell in some of the Apollo 8 audio. They also implied that the Apollo SPS was a hydrogen/oxygen engine, instead of hypergolic. Also, the interviewees implied that Apollo's LES was tested on Little Joe, not Little Joe II, and that Apollo 8 flew a Figure 8 around the moon, when it actually went into lunar orbit.

Still, those are only nitpicks. Both episodes were excellent, with a lot of subjects about Apollo and footage generally ignored by all previous Apollo documentaries as being too dry.

 

[Keatah]

ohh..

 

[Unstung]

Implying that Apollo 8 did not enter lunar orbit sounds like a big goof to me.

 

[cljohnston]

Implying that Apollo 8 did not enter lunar orbit sounds like a big goof to me.

Nope, there was no such implication. Mr. Thorny was digging a bit deeper for nits to pick than I am. (Dang, I knew I shouldn't have quoted that guy's whole post!)
Dale Myers, CSM Program Manager for North American Aviation, was simply waxing poetic about the decision to send Apollo 8 around the Moon, in deference to the mission insignia: "A figure-8 around the Moon. [draws figure-8 in air with finger] Apollo 8 around the Moon."

 

[cljohnston]

I'm on Part 3 now, about the Navigation Computer, and again my jaw is on the floor with all the stuff I'd never seen covered anywhere else, and further impressed with the accomplishment of the Apollo engineers. Anybody ever hear of "[ame="http://en.wikipedia.org/wiki/Core_rope_memory"]Core Rope Memory[/ame]"? Boggles my mind that that even worked!


As for goofs, I wasn't expecting to find any, since I don't really know anything about those types of systems.
But then, after covering Apollo 8, the narrator says: "July twenty-first, nineteen sixty-nine, and Apollo Eleven was three days into its mission to land on the Moon. As the Lunar Module separated from the Command Module, Armstrong and Aldrin were twelve minutes from the lunar surface."
Awww, c'mon!!
Well, first and foremost: Everybody knows the landing was on July 20th. Secondly: Liftoff was on July 16th, so July 21st would be five days into the mission, regardless. And finally: Looking at the timeline, CSM/LM undocking was at 100:12:00.0 GET, with the landing at 102:45:39.9 GET, over 2 1/2 hours later.

 

[Urwumpe]

Anybody ever hear of "Core Rope Memory"? Boggles my mind that that even worked!

Often - even the Shuttle used it until 1987.

Also, on this homepage: http://www.bitsavers.org/

You stumble over a few more historic hardware concepts, like drum computers.

 

[Keatah]

Core rope memory is a dignified and valid way of storing data in an unalterable state as well as being very reliable. It was the best solution at the time.

I remember when we'd program this stuff, it was all by hand, with charts and look-up tables. Lots of basket-weaving and sewing like activities. Took a ton of patience. Especially if you got almost done with a module and decided to change 1 or 2 bits. What a pain!

It would drive engineers nuts if they had to re-wire something, oftentimes the tediousness would necessitate several people working on the same memory module, like in shifts, but only much shorter timeframes.

 

[cljohnston]

Core rope memory is a dignified and valid way of storing data in an unalterable state as well as being very reliable. It was the best solution at the time.

I remember when we'd program this stuff, it was all by hand, with charts and look-up tables. Lots of basket-weaving and sewing like activities. Took a ton of patience.

Just watching them do the weaving, it seems the slightest distraction would be disastrous...

 

[Keatah]

Well those girls were pretty good at what they did, the work was checked and checked and re-checked over and over as the work progressed. So errors on the weaver's end were caught without much backtracking needed.

It was the nightmare when you got a finished module and *YOU* the engineer made a mistake, or made a change based on mission requirements.

Testing the final module to see if the data bits were correct went very quick. You just read the ropes and checked a chart, more or less.

 

[dougkeenan]

Apollo Guidance Computer

 

[Keatah]

A perfect book, I had to charge my laptop batteries 2x since I went through it non-stop almost!

Also, it is interesting to note that in the current political climate in the united states, there really isn't a chance anytime soon of any moon missions. So, as a result, there is more and more interest in Apollo historical media and artifacts. The interest is indeed growing by leaps and bounds.

 

[Urwumpe]

Yeah, but people draw the wrong conclusions from it. They tend to think the Apollo technology was something especially great engineering, but actually, if you think of it in the context of the time, it was brute force engineering.

Rope core memory was a common feature for computers at that time, even some models of the System/360 used it, because memory made of semiconductors was extremely expensive at that time - the rope core memory was the low cost variant. In 1990, you still paid an arm and a leg for a 1 MB RAM extension. Today, RAM is no longer an issue, you get more than your computer can handle for a small price.

Before 1960, you even used 2 Kiloword drums as local storage - the slow predecessor of the hard drive.

 

[dougkeenan]

Engineering that gets the job done is great engineering.