Do you believe the US landed a space ship and astronauts on the moon? (drug, 2015) - Politics and Other Controversies -Democrats, Republicans, Libertarians, Conservatives, Liberals, Third Parties, Left-Wing, Right-Wing, Congress, President - Page 29 - City-Data Forum

Dane_in_LA · 08-27-2011, 01:42 PM

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Originally Posted by DifferentDrum

“It is commonly believed that man will fly directly from the earth to the moon, but to do this, we would require a vehicle of such gigantic proportions that it would prove an economic impossibility. It would have to develop sufficient speed to penetrate the atmosphere and overcome the earth’s gravity and, having traveled all the way to the moon, it must still have enough fuel to land safely and make the return trip to earth. Furthermore, in order to give the expedition a margin of safety, we would not use one ship alone, but a minimum of three … each rocket ship would be taller than New York’s Empire State Building [almost ¼ mile high] and weigh about ten times the tonnage of the Queen Mary, or some 800,000 tons.”
Wernher von Braun, the father of the Apollo space program, writing in Conquest of the Moon

See the 9th word - "directly"? This is von Braun explaining why the lunar mission will not be flown directly, but using a succession of stages. His point - which zooms right over the head of most CTers - is that the mission won't be flown with a single vehicle that takes off from Earth, lands intact on the Moon, and then returns intact. Can't be done. And so it wasn't done.

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Next up is the massive amount of fuel that will be required to power all of those rockets, for both the ascent and descent stages of the mission. The ascent stage in particular is going to be a bit of a fuel hog, as ascending 69 miles and breaking free of the Moon’s gravity is a formidable challenge, to say the least. Though it may only have 1/6 the gravitational pull of Earth, keep in mind that it is still a force strong enough to create the tides here on Earth, 234,000 miles away.

So we make the ascent stage of the LM as light as possible, do some math and build a rocket engine that can handle it. (I have no idea who this idiot you're quoting is, if the thinks that the ascent stage of the LM "breaks free" of the Moon's gravity at any point in time. The LM goes into orbit, which is obviously governed by the Moon's gravity.)

Mass of the ascent stage: 4,700 kg. Ascent engine thrust: 3500 lbf. In 1/6th gravity, that'll do nicely. Incidentally, an RS-18 (that's the ascent stage engine) was test-fired as late as 2008, right here on Earth, and did what it said on the box.

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I’m not a rocket scientist, by the way,

You don't say?

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Next we have to include everything required to keep ourselves alive and well. We aren’t going to be there very long, of course, and space is obviously limited, but we will still require some basic amenities. We will, after all, have to sleep somewhere in the ship, won’t we?

Apollo 12 and forward had hammocks, but until Apollo 15, the stays were short enough that sleeping on the Moon's surface wasn't really a necessity - nor, really, a practical proposition, people were rather excited. I th weightlessness of transit, people just sleep in their harness.

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a sanitation system,

The Apollo astronauts basically cr.pped in a plastic bag held in place with adhesive tape. It wasn't glorious.

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it is imperative that we bring along an adequate supply of food, water and oxygen – and not just enough to last for the planned duration of our visit, but enough to supply a small safety cushion should anything go wrong.

This is supposed to be unsurmountable? All of this were worked out in the Mercury and Gemini days. Unless they were faked, too.

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The oxygen is especially important, so we’re going to need a really good, reliable system to deliver that oxygen, and to, you know, recharge the oxygen tanks in our spacesuits so we can walk around on the Moon and jump like 8” or 9” high like the Apollo guys did.

Ehm - no, they didn't. What a maroon.

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According to the experts over at NASA, daytime highs average a balmy +260° F, but it cools off quite a bit at night, dropping to an average of -280° F. If you’re looking for anything between those two extremes, you won’t really find it on the Moon. It’s pretty much one or the other. If you’re in the sun, you’re going to be boiled alive, and if you’re out of the sun, you’re going to be flash frozen.

So, the author doesn't understand heat transfer, either. On the moon's surface is a vacuum. That means that heat transfer takes place via conduction where there's direct contact with the lunar environment - i.e., through the soles of the boots. And via radiation, which is a sloooow process. There's no convection.

In fact, vacuum is so great for insulation, we use it in thermos bottles.

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I’m not at all sure how the air conditioning system is going to work, come to think of it, since air conditioning requires a steady supply of – and please stop me if I am stating the obvious here – air.

And because this guy who didn't want to listen to his 8th grade physics teacher can't imagine how somethings' done, it can't be done. The thermal control is by sublimation. Liquid water exposed to vacuum sublimates - that is, converts to vapor. That's an endothermic reaction - it consumes thermal energy from the environment. The rest is just plumbing, one can google thermal control garment.

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I never questioned it or cared much one way or the other, but I ran across this article, which is long, but can be read part by part.

It is also written by a complete ignoramus.

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Originally Posted by DifferentDrum

Those suits were able to provide the astronauts with everything they needed to stay alive in the Moon’s harsh environment. Remember NASA’s elaborate rendering of what a Moon work station protected from space radiation would look like?

Due to solar storms. Had the Sun erupted while an Apollo mission was underway, the astronauts would have perished. Luckily, they can be predicted with pretty good accuracy, but this was a calculated risk. For a long-time stay on the Moon, you have to be able to ride out a storm, of course.

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Neil and Buzz didn’t need any of that fancy stuff because they were wearing the magic suits. And those extreme temperatures of +260° F to -280° F? Not a problem when you’re wearing the magic suit. Not only could they provide the cooling needed to combat the searing temperatures in the sun, but they could also provide the heat to counteract those frigid shadows.

Heat transfer again. No convection. So you counteract radiation by making the suits white, you provide insulated boots, and you build-in a sublimation cooler in the PLSS. The basic problem is that of shedding the astronaut's body heat.

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As can be seen in NASA’s photos, the egress side of the lunar modules (the side with the ladder and hatch) was usually in the shade (though almost always well lit). What that means is that, after traipsing around in the sun for a spell, the astronauts would have had to step into the shadows to reenter the spacecraft. And when they did so, those spacesuits were apparently smart enough to react instantly and switch over from turbo-charged air conditioning to blast-furnace heating in the blink of an eye. Awesome!

In the time the author took to type that, he could have educated himself on the relevant physics.

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In addition to providing radiation protection that today’s technology is unable to match, and a climate control system that is beyond anything available in the twenty-first century, the magic suits also provided the astronauts with breathable air, which definitely came in handy. What the suits did, in essence, was provide the astronauts with their own little portable, climate-controlled, radiation-protected atmosphere.

Ehm - pretty much. Engineering is cool.

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Of course, to actually do that (if we’re pretending that it could be done at all), the suits would have had to have been pressurized. And it is perfectly obvious from all the photos that the suits were not, in fact, pressurized, because if they were, the astronauts would have looked like the Michelin Man bouncing around on the surface of the Moon

I guess this joker just argued any spacewalk out of existence?

Again, a bit of reading would have gone a long way. The suits were pressurized to 0.25 atmospheres (having the astronauts breathe pure oxygen lets you do that), which makes it considerably easier to provide mobility. A restraint layer keeps the suits' shape. The joints are engineered to retain a constant volume when moved. Even so, astronauts doing EVA (even today) always have to work hard to overcome the resistance, particularly in the gloves. So we don't send sissies to space, problem solved.

subsound · 08-27-2011, 01:51 PM

LoL

That Mitchell and Webb Look - Moon Landing Sketch - YouTube

ergohead · 08-27-2011, 01:56 PM

I still want to see a rocket land tail-down, using just thrust, on earth, man.

Moon ain't got no landing strip.

Dane_in_LA · 08-27-2011, 02:18 PM

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Originally Posted by jetgraphics

Do the math...
Each Apollo mission was composed of a Saturn V.
Apollo 11 - 17 account for SEVEN huge throw aways (ignoring the orbital missions)
Versus
1 earth orbit shuttle (3 passenger), 1 orbit-to-orbit shuttle (3 passenger), 1 lunar orbit shuttle (3 passenger)
1 earth orbiter, 1 lunar orbiter
...
At the end of each mission, the vessels would remain, needing only fuel and resupply.
...
Frugal? Yes.

In the sense that building a bridge to Hawaii will make it possible to drive there, thus making for frugal travel.

You're hand-waving into existence two orbiting facilities that would need to be launched - and saying that "only fuel" will be needed is rather silly, because fuel and oxidizer is the biggest part of the mass budget.