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/sci/ - Science & Math

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10842445 No.10842445 [Reply] [Original]

Uhhhhh... So... how did we get back from the moon when we didn't have reusable rockets back then?

>> No.10842459

>>10842445
We got 1 use rocket on the moon.

But truth is more lethal.

Have you seen Neil Armstrong? No it was his clone. He stayed on the moon in module, to prove that we are not getting out.

>> No.10842467

>>10842459
They couldn't clone a person back then. They used identical twins to act like they came back.

>> No.10842471
File: 162 KB, 800x1048, LEM.jpg [View same] [iqdb] [saucenao] [google]
10842471

>>10842445
The Apollo Lunar Module (AKA the LEM) was a two stage vehicle. Each stage had it's own engine and propellant. The descent stage, with it's legs and other equipment necessary for landing, was what carried the second ascent stage down from low lunar orbit to the lunar surface. Once the task of landing on the moon was complete and the Apollo crew wished to return to the command module in low lunar orbit, the ascent stage will decouple from the descent stage to fly into an orbit where it'll meet the Apollo capsule. The ascent stage also contains the cabin that contains the astronauts and their gear necessary to explore the lunar surface.

Note that the descent stage is left on the lunar surface, that is because no parts in Apollo were reused. The ascent stage is brought back to Earth orbit attached to the capsule for extra living space for the astronauts, but it gets left to the heat of reentry and is thusly destroyed. Why no reusability? At the time rocket technology wasn't developed enough give such space vehicles both the spare capacity and capability to be reused. On top of that, the incredible goal of sending men to the moon and returning them safely before the 70s required a speedy development of equally incredible technologies and thus left little room to consider reusability when faced with other tasks that were never done before such as orbital rendezvouses and controlled landing on a non-terrestrial body. Those tasks were given priority over reusability to meet the time constraints of Apollo.

>> No.10842477
File: 149 KB, 580x456, 1550623953373.jpg [View same] [iqdb] [saucenao] [google]
10842477

>>10842471
I apologize for any flubs in that post btw, I'm a third into a wine bottle right now. Working towards a half.

>> No.10842483

>>10842445
we didn't reuse rockets

>> No.10842494

Who the fuck was recording this???
>*/sci/ is silent*

>> No.10842507

>>10842494
https://www.hq.nasa.gov/alsj/GCTA-Report.pdf
A camera on the rover that can be remotely controlled from Earth. Before you ask "then how did they time the camera pan correctly with that huge time delay?", the launch of the ascent stage was known about ahead of time and the speed at which the ascent stage flew vertically as well.

>> No.10842522

>>10842471
Its true name is the Lunar Excursion Module and I won't hear any different.

>> No.10842671

>>10842507
That and they tried and screwed it up on the previous mission.

>> No.10842717

>>10842445
We bummed some gas off the moon creatures.
They not teach you this shit in school?

>> No.10842756

>>10842445
I remember that reading as a kid, I thought the Command Module was reused because it was the only part that came back to Earth.

>> No.10843413

>>10842445
Why would we need reusable rockets to land on the moon?

>> No.10843462

>>10842445
https://www.youtube.com/watch?v=VhUGNaLgDJ8

>> No.10843667

>>10842445
You do realize there was an capsule that remained in orbit for the return journey, right? And that the lander only needed enough fuel to return to the capsule?

>> No.10844861

>>10843667
I read that the LM-4 "Snoopy" ascent stage is still in solar orbit, the last surviving flown lunar module. (source: https://space.stackexchange.com/questions/2496/where-were-the-various-apollo-lunar-modules-lms-discarded))

>> No.10844895

How did they manage to film that?

>> No.10844945

>>10844895
See >>10842507

>> No.10845616

>>10842477
I'd be tossing cookies after one whole bottle.

>> No.10846099

>>10843413
If the LEM descent and ascent engine was the same, reusing for both stages, you could save a lot of weight that could be used for more equipment or more sample return.

>> No.10846129

>>10846099
I think some of the early protoypes used that concept. Not sure exactly why it got scrapped but I'd guess it had to do with added complexity.

The ascent stage requires less thrust and throttling capability, so using the larger more complex descent engine for ascent would be overkill. You've also got to have additional complexity to make the engine share fuel from both stages, as well as the mechanisms to have the ascent stage stick down through the descent stage and ascend safely without snagging on anything (landing sites were not flat or level.) Plus you now need an engine that can be reliably lit and relit.

>> No.10846169

>>10842671
they fucked it up multiple times
the ascent stage webm that people say looks fake is of Apollo 17

>> No.10846300

>>10846129
Were the two engines of that much difference in terms of complexity?
Undoubtedly the descent engine needed more thrust, after all it had to carry fuel and also a separate engine for ascent. You could save ascent weight by having separate descent and ascent fuel tanks but I am not sure how much difference that would have in practice. It was separate on the missions but that too adds complexity.

>> No.10846356
File: 68 KB, 700x700, 8289642.jpg [View same] [iqdb] [saucenao] [google]
10846356

>>10842445
Anyone else feel mad sometimes at how fucking easy it is to get to lunar orbit compared to earth orbit

Look at the size of that shit. Wasn't the rocket engine the size of a large briefcase or something?

REEEEEE

>> No.10846432

>>10846356
>Wasn't the rocket engine the size of a large briefcase or something?
No, the RS-18 is about 3ft 11in tall. Still pretty small compared to something like the Merlin 1D or RD-180.

>> No.10846664

>>10844861
There's a really fun KSP mission to go and rescue it and return it to Earth.

It's also worth noting one of the Rhino stage rockets used to push the apollo craft to the moon accidentally missed the moon and went into solar orbit as well. Some amatuer astronomer found it a few years back and thought it was an asteroid until someone noticed its albedo and size were spot on for a rhino stage rocket.

>> No.10847365

>>10846300
The descent engine weighed twice as much, and produced about 3x as much thrust. It also had deep throttling which was new tech at the time.
Relighting engines wasn't easy either because the hypergolic fuels were so corrosive. The ascent engine was never test fired prior to launch because it was one use only. The best they could do was test other engines of the same design.

>> No.10847370

>>10847365
>go on first moon mission
>ascent engines fails to fire

That would have sucked

>> No.10847371

>>10847365
>Relighting engines wasn't easy either because the hypergolic fuels were so corrosive
It wasn't that the fuel was so corrosive, the Aerozine 50 that was used in other rockets can be dealt with. It was that the ascent engine was ablatively cooled (to reduce mass) meant that it couldn't be test fired.

>> No.10847506

>>10842471
Why was helium in the lunar module?

>> No.10847518

>>10847506
Too keep the propellant tanks pressurized even when fuel was being drained. This was important as both the descent and ascent engines had their propellants fed to them just from the pressure difference between the tanks and the engine.

>> No.10847524

>>10847365
>Relighting engines wasn't easy either because the hypergolic fuels were so corrosive.
Sure? RCS thrusters are often using hypergolic fuel and has to be relit many times.

>>10847506
Pressurising fuel and oxidiser tanks.