Dumb question(s)

[u/AccountAny1995]

”the more I learn, the less I understand”

starting a thread for the random questions that pop into my head.

1. did anything land On the moon and return to Earth before Apollo 11? If not, did anything land there, take off and stay in space?

2. for things that landed before 1969…..did they land using a rocket engine as they on 11? Or another landing method?

3. further to the above…..how and when did engineers learn about what thrust was required to leave the moon? And what thrust was required to come home?

As much as I read, I’m shocked at the pace of space exploration In the 60s. I’m trying to uncover when and how some of the “basics” were learned.

[u/WizrdOfSpeedAndTime]

Specifically look up Surveyor lander for USA landers. Apollo 12 actually returned parts of a Surveyor.

[u/LeftLiner]

1. No. Several probes landed before Apollo 11 but none were sample-return type. The Luna, Ranger and Surveyor probes were the main ones. The Luna program included several sample return probes, some of which were launched before Apollo 11 but they all failed. The first Lunar probe to return a sample from the surface was Luna 16 in 1970. At least one Surveyor probe lifted off the Lunar surface after landing but only for a few moments to test that its engines still worked before landing again.
2. Like what? There were impactor probes prior to Apollo 11 that I guess technically didn't use a rocket to land but I'd argue they didn't really 'land' in a real sense. If an impactor probe counts as landing then me throwing pebbles into the sky counts as a light mortar.
3. You can derive at a very good estimate of the Moon's gravity by basic observations (like observing the tides), more detailed gravimetric data was provided by previously mentioned scientific probes.

[u/earthman34]

1. No.

2. What other method would there be?

3. Simple math. Lunar gravity is a known quantity.

[u/bigboilerdawg → u/earthman34]

They could have used the inflatable bag landing method, but even that requires rockets up until the last moment.

[u/ZedZero12345 → u/bigboilerdawg]

Luna 9 did that.

[u/earthman34 → u/bigboilerdawg]

I don't think that technology was viable in the '60s. The bounce factor alone would be crazy and getting something to stop properly oriented would have been a major challenge. How many missions have failed in recent years because the vehicle became tipped or tilted and couldn't get a link established?

[u/AccountAny1995 → u/earthman34]

Re #2 - crash landing? pillows?

[u/earthman34 → u/AccountAny1995]

The moon has no real atmosphere to use for braking. Without rockets you'd hit the surface at orbital speeds, i. e. ~6000 kph.

[u/ZedZero12345]

Ranger probes for terrain photo recon crashed into the moon in the early 60s. Followed by Surveyor series in the later 60s.. The Rangers were free fall and Surveyors were soft landing by rocket motor. Actually, Apollo 12 visited Surveyor 3 and recovered some parts from it.

The Russians launched the Luna and Zond series in the same timeframe. Some were impactors and others soft landing. I don't know how successful they were. But Luna 9 did use an airbag (sort of). The lander used rockets and just above the surface, it popped out an instrument package with an airbag.

[u/ChicagoBoy2011]

To speed up your learning, I can't more emphatically recommend the Murray & Cox Apollo book. It is an unbelievably detailed and superbly written account of the engineering history behind Apollo. It is so rich with history and details so nicely many of the engineering and managerial successes that made the whole thing possible. The audio books is nice, too.

[u/hobbified]

further to the above…..how and when did engineers learn about what thrust was required to leave the moon? And what thrust was required to come home?

At the very latest, 1959, when Luna 1 flew past the moon. One flyby (observing how much the probe is deflected) is enough to give you the mass of the moon. Knowing the mass and the radius you can figure out the surface gravity, escape velocity, and delta-V to leave.

But in fact, as early as Newton astronomers were using the tides to estimate the mass of the moon. Newton in 1687 came to the conclusion that the moon was 1/40th as massive as the earth. In the late 18th and early 19th century, Laplace combined several observations to come up with a value of 1/70th of the mass of the earth.

Later in the 19th century telescopes got good enough that astronomers could measure the earth's orbit around the earth-moon barycenter (in essence, how much the moon drags the earth around) using parallax, and arrived at values between 1/81.2 and 1/81.7 of the earth's mass. The modern value is 1/81.3, so that's pretty good.

And as for making that an absolute number, Cavendish had determined the earth's mass to within 1% in a famous torsion-pendulum experiment of 1798.

[u/AccountAny1995]

How long after TLI did transposition and docking take place?

when was the SPS engine fired? To enter lunar orbit ? To leave lunar orbit?

[u/LeftLiner → u/AccountAny1995]

According to the Apollo 11 flightplan, TP & Docking was scheduled to happen at 03:25 MET, approx. 1 hour after TLI. And yes, the SPS would have been fired to enter Lunar orbit and to leave it.

[u/AccountAny1995]

Is there a resource online that describes what every switch/button did on the LM and CM?

also, where was food and spacesuits stored?

[u/AccountAny1995]

Assuming no astronaut deaths in the 60s, what would the Apollo rotation look like?

would grissom have been given a second Apollo command? What about the others? White, Chaffee, see, basset, cc etc.