
How to Land on the Moon - NaOH
https://newatlas.com/apollo-11-moon-landing/59108
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rkagerer
_When Neil Armstrong brought his Lunar Module, Eagle, in to land, he found
that the site was strewn with boulders and had to very quickly find somewhere
else to put down._

I thought they overshot their intended landing site, in part because Armstrong
missed some visual landmarks when his attention was taken away from the window
several times by a 1202 alarm. The area beyond the site was rocky (which they
knew beforehand) and by the time he located and touched down on a clear spot
they had < 30 seconds of fuel remaining (leading to some clenched butts in
mission control).

~~~
dmix
What would have happened if they hit some boulders with the lander? Was there
a real chance they could have been stuck on the moon?

~~~
agildehaus
The walls of the LM were 0.012 inches thick. A tad under 4x the thickness of a
soda can. You can imagine why hitting anything might ruin your day.

~~~
perl4ever
This raised the question, for me, of just how thick is the sheet metal on a
typical earth-bound automobile.

It appears that steel panels in modern cars are probably something like 0.03
or 0.04 inches thick. Aluminum panels may be 0.05" or 0.06", possibly thicker
or multiple layers.

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netingle
I want to know more... How does one know one is in orbit? How do you work out
when to fire you thrusters to leave orbit and head towards something like the
moon?

~~~
extropy
Radars, star trackers and some math.

Random Google link: [https://timeandnavigation.si.edu/navigating-
space](https://timeandnavigation.si.edu/navigating-space)

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DEADBEEFC0FFEE
One of the early games I played on either my ZX81 or possibly BBC B was a
lunar lander simulator. Really just a timeline and some maths and some dials.
You contolled the decent with some thrusters. Burning fuel makes it lighter,
which changes the thrust. Don't run out of fuel, dont land to heavy, make sure
you land vertically. Good times.

Nope, that's a confabulation.
[https://youtu.be/jlS3fr3t4Fg](https://youtu.be/jlS3fr3t4Fg)

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anonu
I just finished watching the national geographic on Apollo. It's really well
done. The drew on a lot of local news footage which gives you a unique insight
into the era.

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himeexcelanta
Always love newatlas.

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chenster
Don't forget bringing a golf club

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jaco8
I landed on the moon many times in 1975 using the HP-25 moonlander program. It
achieved this in 49 lines of code and a few manualy supplied data points.
Boulders were never a problem.

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somatic
> When the spacecraft is about 2,000 ft (610 m) from target, it switches to
> the landing phase. This is when the computer hands over manual control to
> the Commander, who guides it in for final touchdown. Slowed to a hover, _the
> module can be steered by tilting it like a helicopter to make any necessary
> corrections._

A rocket landing on (top of) a column of thrust and a helicopter suspended
below a disc of thrust are not even remotely the same thing. Classic failure
to reason from first principles.

Here’s a suitable analogy: it’s like the difference between having a center of
mass behind the center of pressure, and a center of mass in front of the
center of pressure.

For the interested layman:
[https://en.wikipedia.org/wiki/Longitudinal_static_stability](https://en.wikipedia.org/wiki/Longitudinal_static_stability)

~~~
jacobolus
> _Here’s a suitable analogy: it’s like the difference between having a center
> of mass behind the center of pressure, and a center of mass in front of the
> center of pressure._

This "analogy" is more abstract than the original statement and is only going
to make sense to someone who more-or-less also understands that one.

How about “it’s like pulling a floating balloon by a string vs. pushing the
balloon from the side and trying to keep it moving in a straight line in both
cases”

Or maybe “it’s like balancing a vertically-oriented baseball bat while holding
it at the top vs. balancing a broom while holding it at the bottom.”

~~~
jacobolus
Erm, sorry, my editing was only half baked above; I tried to change my example
from a broom to a baseball bat and accidentally left both in.

