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moon lander
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You are currently reading a thread in /sci/ - Science & Math

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how did this shoddy looking thing that looks like its made out of tinfoil lift off from the moon and fly back to earth?
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You need rockets to lift that weight off from earth, but it can fly on it's own thrusters since the gravity is 1/6 lower on the moon :^)
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Stupid troll thread but it didn't fly back to Earth. Well, except on Apollo 13.
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How did leaving the moon work?
The CM was whizzing around the moon while they were down in the LM.
Then the LM went up, presumably in an arc to get into orbit?
And then they played catchup with some booster rockets until they docked?
So I guess some timing was required to rendezvouz?
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>>7798252
Yes
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Well first of all, it didn't fly back to Earth, it just flew back to the moon's orbit. The command module flew back to Earth.

Second, it was most definitely not "shoddy." It is built as lightly as possible, true, and it doesn't have to be aerodynamic because it only operates in vacuum. The "tinfoil" is actually an extremely sophisticated thermal insulation, made of many layers of different materials, many of which didn't exist 10 years earlier.

As for why it can lift off from the moon without the giant rockets needed to lift off from the Earth, it's mostly because the moon is a much smaller gravity well. The size of the rocket you need is not linear. The more acceleration you need, the more fuel you need, which in turn requires more fuel, etc. Lifting off from Earth, most of the fuel is used to lift the fuel itself. Another factor is the fact that there is no atmosphere to push through at thousands of miles per hour.
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How well did they have to time the ascent?
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>>7798275
Not terribly well, they aimed to go into a phasing orbit and slowly met up with the CM after going round the Moon a few times, plenty of time built into that to make adjustments as necessary.
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>>7798098
There wasn't much weight to it, hence the tinfoil.
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>>7798286
You need fuckloads of fuel to make it all the way back to the earth, especially when you don't have a bigass rocket thats taking you there. So where is their fuel tank ? Where are the boosters ?
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>>7798298
This post is bait
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>>7798286
Ascent stage:
Mass, empty (2,150 kg)
Mass, fueled (4,700 kg)
It may look like a toy, but it was well designed, weight skimmed to work with lunar gravity, grabrails and ladder only just able to support astronaughts weight etc.
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>>7798090
That's the thing - while on moon they realized they didn't have enough juice to come back to earth. So they stripped most of the ship and replaced parts of it with what you described as tinfoil. On ascent the acceleration was still too low, so they breached a dock adding some velocity. Then to correct the course one of the astronauts had to cut a hole in his suit's glove and escaping air gave him enough thrust to set this ship on a proper course to earth. Whole thing was crazy.
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>>7798370
Listen here nigger
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it didn't anon
>2016
>still believing in american propaganda
>still believing calculators can fly to the moon
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>>7798370
Hold up bitch
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>>7798090
The moon has so little gravity you could throw a stone into its orbit from its surface.
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>>7798370
>the Martian
People claiming it's hard science
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>>7798252
It's not that hard to calculate a rendezvous trajectory, even with basic computers. Pic related if you actually want to learn this shit. It's like 6 bucks.
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>>7798252
Orbital rendezvous is really fun and most easily understood by playing Kerbal Space Program
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>>7798460
>Fun
>Easily understood by playing KSP

Lies. My attempts at rendezvous are neither fun nor easily understood. Shit's hard.
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>>7798460
> Herbal Spaceout Program
DUDE SPACE LMAO
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>>7798473
Weed + KSP = Yesss
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>>7798403
>The moon has so little gravity you could throw a stone into its orbit from its surface.
I hope you're joking but just in case you're not, the amount of delta-v required to enter low lunar orbit from the lunar surface is 1.73 km/s. I'd love to see someone pitch that fast. Granted, that's a hell of a lot less than the 9.4 km/s required to enter LEO from the surface of the Earth.
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>>7798460
>easily understood by playing Kerbal Space Program
Fuck that, I had to make a new game because I killed my entire Kerbonaut corps inside of two hours. Orbital rendezvous are hard as fuck
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>>7798370
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>>7798483
>>7798472
Assuming you are capable of getting near your target craft and reducing relative velocity to the point you effectively have the two vessels parked next to eachother (the easy part), this is how I dock.

1. Make sure the fuel of the orbiter you will be maneuvering has a fuel tank setup which keeps the center of mass fairly static.

2. Make sure your RCS thrusters are evenly spaced from the center of mass, and as far from the center of mass as possible (better leverage)

3. Set the docking port you wish to attach to as the target (instead of the entire craft). Select the port on the vessel you are maneuvering with and click "control from here"

4. Lock your control point to the pro-target marker on the nav-ball (there are selection icons on the left side of the nav-ball when you have SAS turned on)

5. Use RCS controls (I,J,K,L, and H,N) to line up your prograde marker with your pro-target marker (requires continual adjustment usually).

6. Approach at .5m/s until you are about 5m from target port, then reduce to about .2m/s to avoid bouncing off.

Easy-peasy-what-a-sleazy!!
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>>7798090
It never went to the moon
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>>7798528
I appreciate the advice, but I can actually dock decently well. It's the rendezvous I can't do.
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>>7798414
It's harder than most other shit churned out these days.. The math of stripping the ascent vehicle also mostly works out, although it has calls for some odd design choices. e.g. Having the ascent vehicle be Two Stage to orbit when SSTO is possible. The math also implies a specific impulse that's a bit higher than what would be expected for the given fuel mixture. For someone that wasn't a rocket scientist, they did an acceptable job.

The glove thing though was completely retarded and I still can't believe the movie turned that joke into an actual means of resolving the plot. After they blow the hatch in the movie it feels like a different director showed up and they gave up on the whole, "Let's avoid Hollywood bullshit" the film had tended towards before then.
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Flight plan says orbit insertion at 124:30 (7 min after liftoff) and docking at 128:00, three and a half hours later. The Command Module designer was Maxime Faget and the Moon smells like spent gunpowder, they said.
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>>7798562

the moon doesn't have any atmosphere it can't smell like anything you fucking idiot
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>>7798599
>The moon doesn't have any atmosphere so it can't smell like anything
Ignoring the fact that the moon doesn't have air, so you can't breathe anything either. Or that the astronauts couldn't take off their helmets without dying. Or that you *can* smell things without an atmosphere, you fucking idiot. Are there no smells on the ISS?
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>>7798599
but the moon dust they collected can
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>>7798656

That's not the moon that's just dust
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>>7798698
Which makes up a pretty large part of the moon.
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>>7798539
A few tips for Rendezvous.

1. If the craft you are maneuvering needs to catch up to your target, put it in a lower orbit, by about 10 - 15km. (the lower the orbit, the faster the orbit)

2. If the target needs to catch up to the craft you are maneuvering, put it in a higher orbit by about 10 - 15km.

3. Accelerate time until one of the encounter indicators reads about a 15km separation.

>You want to start manually augmenting the approach when the distance reaches about 15km and is dropping, so you have momentum on your side.

4. When you reach the point where the distance between you and the target craft reaches 15km, find the prograde marker on the nav-ball (make sure your nav-ball is in "target mode" by clicking the text on the top that indicates orbit, surface, or target) You want to pull the prograde marker onto the pro-target marker by accelerating toward the side of the protarget marker opposite of the prograde marker.

> accelerating pulls on prograde and pulls on retrograde.

> a good rule of thumb for approach velocities is 1m/s per 10m separation (should be going 100m/s with a 1km separation, 10m/s at 100m separation)

5. To slow your approach in a controlled fashion, orient your craft so the 'front' points retrograde, push your retrograde marker over your retro-target marker by accelerating toward the side of the retrograde marker opposite the retro-target marker.

>acceleration pushes retrograde and pulls prograde.

I hope this helps, got work to do (weed) but I will keep this thread open if any questions arise I will respond in an untimely manner (weed)
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>>7798977
Addition: When looking at the navball you can think of the line that interects your manipulations point, pro/retro-target, and pro/retro-grade indicators as a lever.

Thats the way I look at it anyway. Your manipulation point is the force you apply to the lever to manipulate the pro/retrograde marker, which is the load you are lifting with the lever, in order to deliver it to the pro/retro-target.
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How did the shuttle catch this speeding fucking bullet when it shot up into space?

Honestly how can any of you believe that the shuttle caught this fucking thing based on video evidence.
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>>7798370
>whole thing was crazy
Stopped reading right there
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>>7798090
It was built plenty strong enough to withstand whatever net acceleration it was under (obviously greater than 1/6 G), but didn't need to be designed around aerodynamic considerations (as the moon has no atmosphere, and the LEM wasn't designed for atmospheric reentry). Which means really the only forces acting on it are the weight on the landing gear and the thrust from the engines. No need to worry about building parts of it from flimsy materials that would get torn off flying through the air at 100 mph.

>>7798298
They were able to save on fuel by making it multi-stage, the descent engine and its empty fuel tanks were left behind. An the interior was pretty cramped, it wasn't exactly made to be comfortable for long durations.

>>7798396
"Rocket science" is actually fairly simple mathematically, the hardest part is just making sure all your figures (weight, propellant mass flux, center of gravity, planetary orbits) are correct. And computing power is really a non-issue anyway if you calculate everything in advance and stick to the plan.

>>7799010
What?

>>7799064
>end of post
>"stopped reading right there"
I sincerely hope this is bait.
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>>7798599
They tracked moon dust from their suits into the module, when they took off their helmets again, they smelled the dust that was in the module.
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>>7799010
https://youtu.be/pw_EmpGACT4
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>>7798090
Where are the stars?
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>>7799320
You can't see them because the relatively bright reflected sunlight washes them out.
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>>7799328
What?
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>>7799329

It's daytime on the moon. The rocks are as bright as rocks on earth. Stars are very dim and if your eyes are adjusted to see the ground in broad daylight then they can't see the stars.
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>>7799339

Literally what.
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>i don't understand how somthing is possible
>therefore it's impossible
>QED

Modern discourse.
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>>7799120
>I sincerely hope this is bait.
I believe he was attempting humour.
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Yo, why the fuck haven't we gone back to the moon and set up a giant laser light that we can enable and disable by radio just to prove to any retards that we've been to the moon?
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>>7799484

>pandering to retards
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>>7799345
On a bright sunny day, if you shine a torch at the ground the sun light is too bright in relation to see the light of the torch.
But at night, the light of the torch seems very bright.
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Why are you people so eager to dismiss these videos as fake all the time ? How do you just ignore the footage and witnesses for the moon landings and things like UFO sights with tons of videos ? Not everything is fake you know. Skepticism is fine but denying everything is just pointless.
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>>7798268
>The "tinfoil" is actually an extremely sophisticated thermal insulation, made of many layers of different materials, many of which didn't exist 10 years earlier.
thats why i wear it on my head
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>>7798252
>Get chosen for a manned mission to the moon
>You're the guy that has to stay in the command module
This must sting hard.
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>>7799364
That's pretty much the same reasoning /sci/ uses to argue that reactionless drives and faster than light travel are impossible.
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Saw some of these in the Smithsonian. Flimsy looking. Like a soda can. Those guys who went to the moon had guts.
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>>7799304
>posts video game
LOL
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>>7799711
There's a big difference between "the math is too hard for me" in orbital rendezvous (something we know has occurred many times, unless there is a massive conspiracy that everyone is in on), and "our current understanding of science indicates that this is physically impossible" in FTL and your woo drives.
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>>7799795
>our current understanding
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>>7798090
The only thing that has the appearence of tinfoil here is your head.
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>>7799814

Kelvin was completely correct in the context of Newtonian physics though.

Predicting that Newtonian physics were accurate only on a tiny (astronomcally speaking) frame of reference and that the idea of mass and Gravity was fundamentally wrong was a bit beyond his time (although not too long)
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>>7799484

Because we did the opposite, we put a mirror on the moon that always faces Earth that at space agency can shoot a laser at and reflect back from.
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>>7799814
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>>7799829

There are fundamental problems with the current models too, and they are far from comprehensive. Kelvin's dogma is salient.
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>>7799320
The stars are everywhere, bro. The problem is that the exposure on the camera is far too short to pick up significant light from them, so they appear no different then noise if they even appear at all. This is actually a good thing because it allows the camera to see detail on the surface, like the differences between the astronaut and a rock. If the exposure was much longer, then everything would just look white, as if the camera was taking a picture of the sun through a mirror.

Which is actually pretty cool to think about. The sun is so bright it practically turns rock into a mirror.
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>>7799010
the shuttle is also moving, and they launch the lander on a path such that (hopefully) the relative velocity of them is close enough to zero by the time they intersect that they can dock with a few manipulations...
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>>7799832
>Implying a human had to go there to put a fucking mirror on the moon

a probe could do that no problem
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>>7798370
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>>7799929
>practically turns rock into a mirror
which reflects about 10% of the light
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>>7799320
Do me a favor, go outside during the day and try to take a photo of the stars.
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>>7799339
There's no atmosphere on the moon to refract the sunlight and obscure the sky, so daytime means nothing if the sun is not in your field of view, at least that's my non-expert understanding.

The reason for no stars is because in order to expose the relatively bright foreground (moon surface, astronauts) the exposure settings for the camera are not long/open enough to capture the light from the much feinter stars.

You can emulate this by going outside on a starry night and taking a picture of someone with the flash on (the flash would emulate the bright sunlight shining on the moon's surface). You won't see any stars in those photos.
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>>7799832
Isn't it dirty?
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>>7800074
That ~10% of light is still enough to illuminate the surface of the Earth that is in shadow and significantly warm the Earth, too. Pretty crazy
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>>7798090
Because it's space aluminium foil duh
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>>7798252
Keep in mind they had a speech prepared for the news of their loss if they missed well before they even landed on the moon.

source: http://watergate.info/1969/07/20/an-undelivered-nixon-speech.html
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>>7798090
It's not actually made of tinfoil. It looks like it is, but that's because it's *covered* in tinfoil (for temperature control reasons), but made of perfectly decent structural materials.

It could lift off from the Moon, despite being far smaller and less sturdy than an Earth ascent rocket, because:

>1. No atmosphere to get in the way, and thus no need to account for the rigors of atmospheric ascent at high velocity, or to add extra thrust to deal with drag.

>2. Dramatically lower gravity, thereby meaning you need much less thrust, and so your ship doesn't need to be anywhere near as sturdy.

>3. A much shallower gravity well, meaning much lower delta-V is needed. Because the rocket equation (the equation governing the amount of rocket you need to transfer some amount of payload) is exponential, this causes a radical reduction in the amount of fuel needed compared to going from Earth to Earth orbit. For instance, a given rocket engine might take 9 tons of propellant to lift 1 ton of payload to Earth orbit, but only 0.6 tons of propellant to lift that same payload off the Moon to Lunar orbit.
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>>7800513
Oh, and
>and fly back to Earth

It didn't. The actual flying-back-to-Earth parts of the spacecraft were left orbiting the Moon (with poor forgotten Michael Collins aboard) while the landing-on-the-Moon part** was detached and landed. After it lifted off again, they reattached it.

*The Command/Service module
**The Lunar Excursion Module
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>>7798090
One for the Moon and one for the Studio.
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>>7799733
>Flimsy looking. Like a soda can.
One of my lecturers back at university was working on the space race projects. he told us stories that you never hear in the flag waving shows or glossy books. He put it plainly that it was like rubber bands and chewing gum that held things in place and it sure was flimsy looking. There was simply not any margin for extra sturdiness or margins.

It was a cold war space race against the Soviet Union. It was victory or death. And they made quite a few contingency plans in case of death. In hindsight it is amazing things went as well as they did but it was a different era. It was in the same era that they got the Blackbird operational in five years.

Then something happened, not sure what. Space became the domain of career bureaucrats with no goals other than their own career and thus got the Space Shuttle with all the problems that brought. It is also a sign of our time that F-35 is not yet really operational.

As I said, the space race was a long, long time ago.
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A soda can is actually also a pretty impressive feat of engineering, if you think about it.
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>>7799829
Newtonian physics was the ONLY physics in Kelvin's time. Everything under physics was covered by Newtonian physics. It really doesn't seem so unreasonable that we will someday develop a new branch of physics that's radically different from our current understanding, just like relativity was compared to the old Newtonian model of physics.
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>>7798090
They hung what was basically tin foil on it. This is common for thermal management in space. There's no wind to blow it off, and small holes don't cause a problem, so it's not like they need a durable outermost surface.

That tells you nothing about how it was built underneath. You could hang tin foil on foot-thick armor plating if you want.

However, it was very lightly built and fragile. The forces involved in landing and return to orbit are small. Lunar gravity is only about one sixth what we have on Earth, so the accelerations needed to land on and launch from the moon are similarly small.

The astronauts had to be careful with the lander, because they could basically have torn it apart by hand if they wanted. While they were being made, minor incidents like dropped tools caused serious damage.
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>>7800533
>Michael Collins
I love space and literally never heard of this guy, what a fucking looser.
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>>7802206
The Blackbird leveraged many decades of aviation knowledge, and it took 5 years. The Apollo program took only 8, and had far less robust tech and knowhow to leverage, plus had the challenge of the unknowns of operating in space and the moon. I don't think you can compare the two, the Apollo mission was a monumentally greater challenge.
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>>7802206
How's it going in Canada, eh?
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>>7803060
That's not a picture of the Avro Arrow.
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>>7802206
It's not like the Saturn V wasn't a super expensive boondoggle either
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>>7802987
>The Blackbird leveraged many decades of aviation knowledge
How many decades of titanium clad aerospace structures were you aware of? Considering the plot to just get the material it cannot be many.

Anyway Apollo was based on Mercury and Gemini which were based on German technology from the 1930's.

My experience form industry, including aerospace industry is that the beancounters now call the shots. Not so back then, and that is the ear my lecturer told us about. That time they needed, absolutely needed, the results and engineers and scientists were i charge of getting those results.

Then came the rot. Technical guys warned about launching Challenger. Bean counters said "go!". And 7 astronauts were killed. Normally this would be regarded as murder. None were ever investigated. None will ever face trial.
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>>7798414
it's hard science for hollywood
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>>7798090
>looks like its made out of tinfoil
it pretty much was in the grand scheme of things
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