The Absence of Airlocks

[bobdude11]

Shutting the door would not have stopped the vacuum of space from entering but it would have stopped any potential harmful dust floating around from entering the cabin.

Surely you understand that dust does not float in a vacuum in any place with gravity?  When the dust is kicked up by engines, spinning wheels or boots, it moves in the same manner as if it is a rock tossed into the area above the ground.

On a planet with an atmosphere, dust will be suspended in the air.  In a vacuum dust moves in an arc then falls to the ground like heavier particles

Ranb

Not to mention, the hatch DOES stop the vacuum of space from entering - or the astronauts would have been dead.

[bobdude11]

…

With regards to the main topic, nobody has given any sort of scientific explanation to the questions I have asked. People point out correctly that other spacecraft have carried the same technology, batteries etc. What they are ignoring is the fact is these components were insulated from the harshness of space. And in terms of dust, apparently there is a dust cloud circling the moon. (plus micrometorites hitting the surface constantly) And even ignoring that, as someone pointed out, they should have been more concerned about the dust on their suits. Another significant reason they should have had a airlock. And the LM windows? They were in shade. The DAC footage shows that as the sun is low and from behind.

Jay. You asked me what batteries are in the cabin. My original post pointed out the DAC camera for instance. It had two batteries that fail below -30 Celsius.  Only one posters has attempted to answer the DAC issue. OneBigMonkey said  "a) it very obviously did and b) it produced film showing details that could not have been reproduced on Earth." It obviously did? That's not an answer. And footage that could not be produced on earth. Of all the footage, this DAC A11 footage seems the most "earthlike" of any footage. Very short strides, easy arm movements etc. And you say that footage can't be replicated on earth?

In any event, somebody show me how hours of exposure to the vacuum of space away from the sun's radiation will not drop the temperature of objects drastically. Further, what scientific process will bring these object back up in temp, fast, efficiently and safely, to environmental temperatures humans can operate in without any aids?

But they have given scientific answers (albeit, much simplified for folks like me that wouldn't understand all the maths) - you choose to ignore those and post another rant.

You have been on here previously, posting things showing your lack of a basic understanding of the engineering involved (or anything else related to Apollo for that matter). you have demonstrated an inability to learn, much less understand.

Why do you NEED Apollo to be fake, so bad? What is your goal here?

Also, to be clear, I believe that Apollo 11 was landed during Lunar noon (or something of that nature) so there were no serious temperature swings (I am attempting to recall this from some other threads I read on here). The end result being: They (and the LM) were NOT exposed to +200 to -200 C temperatures that you allude to.

[raven]

Actually, Apollo landed in the lunar morning, for two reasons I can think of off the top of my head. One, the surface is not as hot, and two, the longer shadows made navigation easier. At least this is my understanding. The engineers in the crowd are more than welcome to explain how I am wrong, and I, in fact, encourage it.

[sts60]

I’m late to the party, but bobdude11 has a good point:the LM was sitting on a warm surface during each mission (I have figures somewhere, and other people have posted them previously too).  Basically half of what the LM saw was warm Moon.  Roughly half the LM saw hot Sun. The LM also saw cold space.  The properties of the LM exterior were designed to manage this radiative environment.

The interior of the LM saw a little warm Moon and cold space, but was mostly insulated from the outside by vacuum.  jr Knowing’s understanding is exactly backward.

[jfb]

In a vacuum, the only methods of heat transfer are conduction and radiation.  Since the crew cabin was fairly well isolated from the lunar surface, I think we can ignore conduction and focus solely on radiation. 

[At this point I have to rely on external sources - I’m a code monkey, not an engineer or physicist]

This page shows how to compute the rate radiative heat loss using the Stefan-Boltzmann law.  With some rearranging and integrating, you can compute the rough amount of time it takes for an object to cool down from a high temperature to a lower one.

Keeping things “simple”, a solid block of unpolished aluminum (emissivity 0.09) just 10 cm on a side will take around 8 hours to go from 300 K (about 80 deg F) to 255 K (just under 0 deg F).  That’s...not that cold. To cool down to 100 K (roughly -280 deg F) would take around 13 days.  And that’s assuming there’s nothing heating that aluminum block (internal electronics or the Sun). 

IOW, this ain’t Hollywood.  Things and people don’t immediately freeze upon exposure to space.  It takes nontrivial amounts of time for objects to lose heat strictly through radiation.

Now, the crew cabin isn’t a solid block of commercial sheet aluminum 10 cm on a side - there are a bunch of different materials with different emissivities, densities, etc., and most of it’s built in thin sheets.  It’s also full of electronics and heaters to maintain stable temperatures, and it’s standing in the Sun the whole time. 

So evacuating the cabin for a few hours is simply not a big deal from a thermal management perspective.

I realized it would help to show the work (I typed the above from an iPad without a keyboard, which got ... frustrating when I tried to add the math):

We start with the Stefan-Boltzmann law as described here:

    P = dE/dt = emissivity * sigma * surface area * ( T⁴_hot - T⁴_ambient )

where

   P is the total power emitted in Watts
   E is the energy of the system in Joules (power is energy change over time)
   emissivity is the effectiveness of emitting radiation (between 0 and 1, where 1 is an ideal emitter)
   sigma is the Stefan-Boltzman constant 5.670374419 x 10^-8 W m^-2 K^-4
   surface area is in m²
   T is the temperature of the object in Kelvin

With some rearranging and integrating (see the page linked above for details), we get

    t = (Nk / (2 * emissivity * sigma * surface area) ) * ( T^-3_ambient - T^-3_hot )

where

   t is cooling time in seconds
   N is the number of particles in the system (atoms, molecules, etc.)
   k is the Boltzmann constant 1.380649 x 10^-23 J/K
   
For my example, I computed the number of atoms in a 10 cm³ block of aluminum by first computing it's mass (assuming density of 2.7 g/cm^3, that's 2700 g or 2.7 kg), multiplied that by Avogadro's number, then divided by the molar mass of aluminum (29.98 g/mol), giving me an N of 6.03 x 10²⁵.  I picked an emissivity of 0.09 for unpolished aluminum from here. Plugging that into the above formula gave me

    (6.03E25 * 1.380649E-23)/(2 * 0.09 * 5.670374419E-8 * 0.06)(255^-3 - 300^-3)

which gave me around 3.16 x 10⁴ seconds, or 8.78 hours.  Note that this is the minimum, ideal cooling time - it will be longer in the real world. 

This is consistent with the calculator on that page which uses a sphere, rather than a block, and the numbers are close enough for me to be confident I'm doing it right. 

So you can play around with this - pick different materials, different geometries, etc., and compute how long it would take for those items to radiate away all their heat. 

And remember, a vacuum isn't cold or hot - the concept of temperature doesn't really apply to a vacuum.  Things will get cold in space if they radiate away all their heat and there's nothing to warm them up again.  But the mere absence of an atmosphere by itself doesn't make things cold (otherwise Thermos bottles wouldn't work very well). 

[JayUtah]

I realized it would help to show the work...

And well done.

Things will get cold in space if they radiate away all their heat and there's nothing to warm them up again.

That's where the math makes you cry, because practical solutions require adjusting the single-surface computations to accommodate incoming radiation from other sources, including heat radiated from portions of a convoluted surface (belonging to the same object) that can "see" each other.  This is what the 13-element model for the LM was meant to accomplish.  The student might ask, "Do those effects matter?"  The answer in many cases is, "Yes, they do."  Portions of the LM radiated away their heat in directions that other parts of the LM could see and receive energy from.  This affects how rapidly they themselves cool by radiation, because T_hot is not a simple value.

[jr Knowing]

Hi Everyone,

First off, Mako88sb asks what it will take to convince me the Apollo missions were legit. To be clear, I am not 100 percent convinced they were hoaxed. As I have pointed out in the past, I believe the visuals, ie photos and films were faked. I am confident in my mind they were faked (and I am pretty certain of who some of the individuals that were involved). But fake photos don't necessarily mean the missions were faked. My stance currently is the photos/films are fake but I am unsure whether the missions actually took place. It is a bit of a stupid stance given if the pictures were faked, odds are the missions were faked too. But I have doubts. Some of the answers on this forum, for instance, have at least shown a plausibility of some things I thought were dubious. I think what is important here, people need to respect the thoughts of others, how much you may disagree with them. As far as I know, no one has a monopoly on truth.

Case in point, many of you guys profess to know everything about these missions and their scientific underpinnings. Well here is Jeff Bezos, who clearly knows, I would think, more about the complexities and issues of putting a man on the moon then anyone here, looking straight into Michael Collins eyes telling him the Apollo missions should have been impossible. He says it to him three times in two minutes. (he starts by clearing his throat at the .15 second mark. lol ) He then follows that up by saying even today we still haven't figured out many of the processes to get a man to the moon.  But instead of saying the missions didn't occur, he comes up with some bizarre gibberish to rationalize the missions occurred. He literally argues the Apollo missions were in some time warp in which the Apollo program was able to jump forward in time, use future technology, jettison the technology, and then go back in time. Absolute nonsense. But this is how he rationalizes the missions occurred. (This is not unlike astronaut Don Pettit (longest serving US astronaut) rationalization that "NASA destroyed all the technology".) Why? Because, given his intimate knowledge of the subject, he can't come up with a logical coherent explanation on how NASA accomplished those missions 50 years ago.  He literally says "we have to wait for technology to catch up". WTF? This from the man spending billions to put a man on the moon. These comments should be very sobering to everyone who thinks thinks they understand what happen in these Apollo missions. People should really take a step back and digest what he is saying. The only way he felt these missions occurred is because they were in a time warp. Tell me. What is more ridiculous? The Apollo missions were faked or the Apollo program was in a time warp and really traveled into the future?   

[raven]

Objection, Your Honour.  Opposing council needs to demonstrate relevance.
Though one thing is clear. You can't even answer a simple question by a non-engineer, why wouldn't  Grumman engineers wouldn't have added an airlock to the design if it was so necessary  as you so insist, even in the event of a hoax, so, instead, you turn to subjective, wishy washy 'evidence'.

[sts60]

...Case in point, many of you guys profess to know everything about these missions and their scientific underpinnings. Well here is Jeff Bezos, who clearly knows, I would think, more about the complexities and issues of putting a man on the moon then anyone here, ...

I’ve been in aerospace for almost three decades.  And I’m not the most knowledgeable poster here.  Please don’t project your ignorance onto others.

[JayUtah]

I think what is important here, people need to respect the thoughts of others,

No.  If you base your accusations on ignorant rubbish, it will be called out as ignorant rubbish.  Stop whining about how badly you think you've been treated.  Ignorance is not a point of view, and your ham-fisted forays into social engineering have never worked.  It's not a matter of "disagreement."  When it comes to heat transfer, you are simply wrong.  Being wrong has consequences.

Case in point...

No, it's not a "case in point."  It's a feeble attempt at distraction after having your head handed to you once again.  You're not an engineer.  You don't know how engineering works, or how space works.  And you won't give any respect to those who do.  I don't see you apologizing for foisting layman's misconceptions about heat transfer and expecting people to take them at face value.  No, you dishonestly run frantically away from your glaring errors and pivot quickly to some other argument.  You even smugly tried to claim you knew the subject better than others.

Well here is Jeff Bezos, who clearly knows, I would think, more about the complexities and issues of putting a man on the moon then anyone here...

No.  He's a guy with piles of money who attracts media attention.  He hires people like me and some of our other regulars to work out the actual technology.  Your "argument" is nothing more than you pretending you know why people in a YouTube video are acting the way they do.  It's wholesale speculation.

[JayUtah]

He literally argues the Apollo missions were in some time warp in which the Apollo program was able to jump forward in time, use future technology, jettison the technology, and then go back in time.

No, that is literally not his argument.

The Apollo missions were faked or the Apollo program was in a time warp and really traveled into the future?

Wow.  It's been a long time since I've seen someone so desperate to stretch another person's words into the realm of the absurd.  Are you actually trying to say that Bezos was referring -- literally -- to time-travel?

[jr Knowing]

Hi Jay,

Actually Bezos is saying that we used technology in Apollo missions from the future. Plain and simple. You have the right to disagree.

But I need to point out something. Are you a linguistics PHD? Why is it everyone is allowed to express their opinion sans credentials when it suits you? But if someone's opinion doesn't suit yours, you demand to see their PHd in Thermodynamics, rocket science etc. Reflect on your previous posts, and you will see that.

[JayUtah]

Actually Bezos is saying that we used technology in Apollo missions from the future.

No, he isn't.  He's merely claiming that it was an anachronistic leap.  Nowhere does he mention time travel.  That's entirely made up.  By you.

You have the right to disagree.

I do, and I do.  But claiming that Bezos is talking about literal time travel is absurd on its face.  You don't have the right to demand respect for patently absurd interpretations of other people's statements.

Are you a linguistics PHD?

No, and neither are you.  Gleaning the proper understanding of sentences spoken in a common language is within the layman's ken.  In this particular case, Bezos is talking about the industry I work in, so I will claim a greater ability than yours to put those comments in a useful perspective.

But if someone's opinion doesn't suit yours, you demand to see their PHd in Thermodynamics, rocket science etc.

Thermodynamics, heat transfer, and all the other engineering topics you've pretended to understand are not matters of opinion.  They are matters of fact.  You got the facts wrong, and you're pulling out all the stops to avoid having to pay the consequences for that.  You are not entitled to have your ignorance respected.

Reflect on your previous posts, and you will see that.

Kindly don't talk down to me.  You are not some zen master.  You're just the same run-of-the-mill sort of charlatan that wants credit for things he hasn't earned, and wants to pretend he's some otherwise deep thinker.  Get over yourself.

[jr Knowing]

Hi Jay,

Again. You read what you want to read. I said time warp.

Time Warp:A hypothetical discontinuity in the flow of time that would move events from one time period to another

[JayUtah]

Again. You read what you want to read. I said time warp.

And Bezos did not.