Moon Landings for Dummies

[+ouija ouija]

Hello there all you serious and knowledgeable Space Exploration and Space Flight fans .

Please would you take time to answer some questions I have? These are some points that stood out for me when I watched a video of an interview with Neil Armstrong, about working towards the first Moon landing(the simplest possible explanations would be appreciated ..... thank you):

1 Before anyone actually landed on the Moon, how did scientists know it had low gravity?

2 ditto 'No atmosphere on the Moon'? He(Armstrong), said "You're flying in a vacuum" .... how did they know that?

3 He said they had 20secs of fuel left when they landed. Why didn't they have more fuel on board? I know it's all extra weight, but seriously ..... 20secs?!!

4 Why have the Russians never attempted to put a man on the Moon? Finance wouldn't be a problem, surely? At least they would then be equal, not 'less' than their arch-rivals the Americans.

5 Have the Russians ever claimed that the Americans did not land on the Moon?

Before you say "why don't you all Google this?", I know I could but I probably wouldn't be able to understand half of it! I would like to be able to communicate with a real person who can answer any secondary questions I have.

Thank you.

[+OverSword]

Why don't you google this?

Sorry ouija, just pulling your leg.

[+ouija ouija]

*slaps*

[MissJatti]

why not ask your idol lord shiva

[+ouija ouija]

why not ask your idol lord shiva

Do you have his address? number?

[+and-then]

I know? a little. I'm sure there is a formula in math that can use the size of the object to calculate the gravity. The fuel issue wasn't planned - they either over flew the landing site or couldn't find it as planned so they had to improvise. When you listen to the team on the radio they say "you've got a bunch of guys about to turn blue here" or something like that. Until I heard the full story later that comment didn't make much sense.

I've never heard the Russians question the truth of the landing. I think the issue with vacuum was assumed since there was never any observable weather on the moon's surface. That's all I can guess on - someone will come along directly and REALLY explain it I'm sure

[TSS]

You can work out gravity from mass and distance, and mass from distance and orbit. Even the ancient greeks work distance out to within 8,000 miles, which is something you can look up if you want the exact method. The Russians? no they never claimed the Americans never landed on the moon, I can't think of any reason why the Russians would want to make themselves look incompetent by making up something like that.

[theotherguy]

The pull of gravity is the mass of one object multiplied by the mass of another object, then divided by the square of half the distance between the two objects. If one object (the moon) has substantially less mass than another object (Earth), it will pull much more weakly on a a nearby object (an astronaut). I forget how they derived the mass of the moon, though...

[Waspie_Dwarf]

1 Before anyone actually landed on the Moon, how did scientists know it had low gravity?

The surface gravity an object is a direct result of it's mass and radius.

The radius of the Moon can be directly measured.

Mass can be determined by using Kepler's 3rd Law, which relates the mass of a body to the distance at which if orbits an other (in this case the Earth) and the period it takes to complete an orbit. Since the distance from the Earth to the Moon can be measured, as can the time the Moon takes to complete one orbit it's mass can be determined.

Since the Moon's mass and radius are known it's surface gravity can be calculated.

2 ditto 'No atmosphere on the Moon'? He(Armstrong), said "You're flying in a vacuum" .... how did they know that?

That the Moon has no atmosphere has been known since Victorian times. It is simple to prove. When the Moon occults (passes in front of) a star if there is an atmosphere the star will visibly dim before the Moon cuts off all it's light. If there is no atmosphere the star will simply disappear as the Moon passes in front of it. The second of these scenarios is what is actually observed, therefore the Moon was known to have no atmosphere.

3 He said they had 20secs of fuel left when they landed. Why didn't they have more fuel on board? I know it's all extra weight, but seriously ..... 20secs?!!

As Apollo 11 came in to land Armstrong noticed that they were heading towards a boulder field. He took manual control and over-flew the original landing point. This used more fuel than was originally calculated.

4 Why have the Russians never attempted to put a man on the Moon? Finance wouldn't be a problem, surely? At least they would then be equal, not 'less' than their arch-rivals the Americans.

The Russians did attempt a manned Moon programme. They had huge problems with there equivalent of the Saturn V, known as the N1. In 4 launch attempts between February 1969 and November 1972 it exploded 4 times. The Soviet Union abandonded it's Moon programme in 1974.

5 Have the Russians ever claimed that the Americans did not land on the Moon?

Well some individuals have, but the Soviet government congratulated the USA on it's achievement.

Edited March 27, 2014 by Waspie_Dwarf

[+ouija ouija]

Prize for best post so far goes to Waspie-Dwarf! Thank you, Waspie.

[ChrLzs]

A couple of small additions...

Armstrong was actually down to a 30 second landing fuel warning - that didn't mean it would run out in 30 seconds. The warning was so he knew IF he had to abandon the landing attempt, he needed to do it within 30 seconds or so, or he might not have enough fuel to re-ascend into orbit and safely dock with the orbiting CSM..

If he had aborted and re-ascended to the CSM without landing, he and his crew would have been able to safely return to Earth, but they would have missed their chance to be first.... and the crew of Apollo 12 would have been the next to try.. Needless to say that was quite an incentive for him! So he made the judgement to continue, got it down safely well within the safe time limit and his judgement was dead right.

Many reports of the landing neglect to explain what the 30 second warning actually meant, preferring the implied drama that they were about to crash!!! But the 30 seconds was a carefully calculated value for a safe decision point and it left a significant safety margin. So he would have known that in reality he had more time than that to truly make the final decision. Even though it would have given some mission control staff heart attacks! (Somewhere those margins are available - if you want I can chase them down..)

Also, note that not only did the Russians congratulate the USA (perhaps grudgingly - it certainly wasn't as well promoted in the Russian press!), they had to.. They had tracked the mission all the way to the moon and also listened in to the transmissions by intercepting them with directional antennas pointed at the moon (it is impossible to fake that). In addition, apart from any spying that the Russki's were doing, the entire Apollo mission was incredibly openly and comprehensively documented - anyone could verify all the technical details (and many did and still do). This unprecedented openness happened largely because of the terrible Apollo 1 tragedy which cost 3 lives and almost killed off the Moon program. NASA knew that it had to change its approach completely, and what better way than to open the mission to high level scrutiny by anyone and everyone.

IMNSHO, the Apollo project was without doubt the most ambitious technical achievement ever undertaken by mankind, and I doubt whether anything we do will ever overtake it in terms of the huge leap in our technical abilities that it demonstrated. I can still vividly remember the drama leading up to the landing and the way the entire world came together and held its breath... and then the euphoria when they made it and also returned safely... Those were wonderful times, even if it was all fairly shortlived. By the time we got to Apollo 17, it seemed that it had all become routine.. (not to me, though!)

Sadly we live in a different world now...

[Whisperer]

"Sadly we live in a different world now..." so true, I was fascinated with it all but it got boring after a while as the TV didn't show much of what was going on in my part of the world, just printed 'news reports'.

[Waspie_Dwarf]

IF he had to abandon the landing attempt, he needed to do it within 30 seconds or so, or he might not have enough fuel to re-ascend into orbit and safely dock with the orbiting CSM..

An addition to the addition.

The lunar module was actually 2 modules, the descent module and the ascent module. The ascent module used a different engine and had separate fuel tanks from the descent module. Even if the descent module HAD run out of fuel there would have been enough fuel to abort the landing and return to orbit.

[ChrLzs]

The lunar module was actually 2 modules, the descent module and the ascent module. The ascent module used a different engine and had separate fuel tanks from the descent module. Even if the descent module HAD run out of fuel there would have been enough fuel to abort the landing and return to orbit.

Yup, exactly.. It's an interesting topic and I've seen some discussion about the logistics of 'dropping' the descent module before they landed and then quickly lighting up the ascent stage's rocket to get back up... and I think the astronauts were a bit nervous about that possibility. If they left everything *way* too late and had to do all that close to the ground, it could have been nasty!

But as it turned out, the hardware performed so well that everything went wonderfully smoothly for every mission (but one.. and with a few tiny exceptions.. ) Given this was all developed and done in the 50's, 60's and early 70's, I think it is an absolutely brilliant example of just how clever we can be if motivated..

And all without Google, let alone a single personal computing device!!! Long live the slide rule, I say!

Edited March 27, 2014 by ChrLzs

[Waspie_Dwarf]

Given this was all developed and done in the 50's, 60's and early 70's, I think it is an absolutely brilliant example of just how clever we can be if motivated..

In February 1945 my father (who was 8 at the time) received what he referred to as, "a present from Werner Von Braun," a scar on his head from the impact of a V2 that hit the suburbs of London.

Just over 24 years later, as a three year old, I sat on my fathers lap and watched 2 men walk on the Moon, the result of a present to the entire human race from the same Werner Von Braun.

Today rockets have the capability to send us all to oblivion or to send us to other worlds. To end the human race or to make our species virtually immortal. I think (hope) we will choose the latter.

Edited March 27, 2014 by Waspie_Dwarf

[Peter B]

Hello there all you serious and knowledgeable Space Exploration and Space Flight fans .

Please would you take time to answer some questions I have? These are some points that stood out for me when I watched a video of an interview with Neil Armstrong, about working towards the first Moon landing(the simplest possible explanations would be appreciated ..... thank you):

[snip]

4 Why have the Russians never attempted to put a man on the Moon? Finance wouldn't be a problem, surely? At least they would then be equal, not 'less' than their arch-rivals the Americans.

I just thought I'd contribute a few thoughts on this question, seeing as the other questions have been fairly comprehensively answered.

The first answer, as Waspie_Dwarf pointed out, was that the Soviets (not Russians - a subtle but important distinction) did have a program to attempt a manned lunar landing, but the rocket needed for the program just couldn't be made to work. Had the N-1 worked, it would have carried a Soyuz spacecraft on top, the Soyuz being designed with a moon landing mission in mind. It would have also carried a second spacecraft called the LK, which was the Soviet equivalent of the Lunar Module. The LK was actually tested four times in Earth orbit in 1970-71, although the missions were given deliberately anonymous Kosmos designations - the Soviets didn't publicly admit they were testing a lunar lander.

But there was also a geopolitical dimension to why the Soviets didn't attempt a manned lunar landing. It was the Cold War - an ideological conflict between the two most powerful countries in the world. The Space Race was simply another front in that war, one in which technological skill was the weapon, intended to convince undecided nations around the world that the Americans or Soviets had the better technology. The Soviets took an early lead in the Space Race, launching a satellite first, sending an animal into space first, sending a spacecraft to the Moon first, and sending a man into space first.

From an American point of view early Soviet successes in the Space Race were a disaster, and this is what prompted President Kennedy to set the challenge of landing a man on the Moon and returning him safely to the Earth. The thinking behind the challenge was that it was difficult enough that a whole new generation of rockets would be needed, giving the Americans a chance to catch up. Hence the Saturn V and N-1 rockets.

Although the Soviets never publicly acknowledged at the time that they were in a race, we've known since the fall of the Soviet Union that they certainly behaved that way. Right up until Apollo 11 the Soviets were designing manned missions intended to steal the Americans' thunder, but the unmanned test missions required before the manned missions couldn't be made to work.

So why did the Soviets give up? Wouldn't getting to the Moon make them equal to the Americans, even if it came after the Americans? The answers to these questions go back to the nature of the Cold War - it was a conflict between only two nations; coming second was the same as coming last. While, say, we might admire everyone who completes a marathon, even if they don't win it, from a propaganda point of view the Cold War was very different: doing the same thing as your opponent after they've done it means you've lost. The way around it was to not be publicly seen to be in a race you might not win. As a result, rather than doing what the Americans had already done, the Soviets concentrated on doing something else first. So they sent unmanned sample retriever missions to the Moon, pointing out (correctly) that these missions were much cheaper than the Apollo missions, and didn't risk anyone's lives. The fact that the Soviet sample return missions returned a tiny fraction of the data and lunar material of the Apollo missions was a subtlety lost on most people.

[Waspie_Dwarf]

So why did the Soviets give up?

The reasons why the Soviets gave up is complex and mired in the internal politics and personalities of the Soviet Union's space programme. It also gives us an insight into why the programme failed in the first place.

Until his death in 1966 the identity of leader of the Soviet Union's space programme was kept a state secret. He was known to the outside world as "The Chief Designer". His name was Sergei Pavlovich Korolev.

However Korolev did not lead a united space programme. The Soviet Union had no equivalent of NASA. Instead there were many different design bureaus. These were often fiercely competitive with each other, sometimes to the detriment of the Soviet space programme. Each bureau was favoured by different members of the Politburo, so fortunes shifted as politicians fell in or out of favour.

One of these rival bureaus, OKB-52, was run by Vladimir Nikolayevich Chelomey.

Had the two men combined they may have give the American's a real race to the Moon (even with the far small budget at their disposal). However they fought rather than united. Chelomey had has own plans for the Moon, using his UR500 rocket (still in use today, we know it as the Proton). Chelomey refused to work on Korolev's N1.

Another designer was Valentin Petrovich Glushko. His genius was in designing rocket engines. However by all accounts he was bull-headed and egotistical. He also felt (probably correctly) that he didn't get his share of the credit for Korolev's successes.

Korolev wanted Glushko to build large rocket engines which used liquid oxygen as an oxidiser. Glusko refused. As a result, unlike the Saturn V which used just 5 engines (which used liquid O₂ as an oxidiser) in the first stage, the N1 ended up with 30 engines. It made it a plumbing nightmare and lead to the fires and explosions that occurred on all four launch attempts.

With Korolev dying in 1966 there was no longer his genius behind the project. Maybe he could have sorted the problems out. Sadly we will never know.

After his death Korolev's deputy, Vasily Pavlovich Mishin, became chief designer and he continued with the N1. However Mishin was replaced in 1974... by Glushko. Glushko quietly killed the N1 and his part in its failure was hidden from the outside world until after the fall of the Soviet Union.

If you wanted me to sum up why the USA landed men on the Moon and the Soviet Union didn't in one sentence it would be this; "because the USA had NASA".

Edited March 27, 2014 by Waspie_Dwarf

[+ouija ouija]

Ripping stuff! Thank you everyone who replied

[Peter B]

Incidentally, if you'd like to learn more about the Space Race in the context of the Cold War, I can highly recommend the board game "Twilight Struggle" by GMT Games. It's a game about the Cold War, with one player controlling the USA and the other the USSR. It's mostly about building influence around the world using cards which represent historical events from the Cold War, but the Space Race plays an important if peripheral part in the game: success in the Space Race earns victory points, and if one side builds a big enough lead in the Space Race they gain small but useful advantages.

But the game overall is thoroughly interesting and fun to play.

[+ouija ouija]

I love board games