2172: "Lunar Cycles"

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mschmitt
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2172: "Lunar Cycles"

Postby mschmitt » Fri Jul 05, 2019 6:45 pm UTC

Image
Title text: "The Antikythera mechanism had a whole set of gears specifically to track the cyclic popularity of skinny jeans and low-rise waists."

What is the cycle for when the Moon is scary bright?

jgh
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Re: 2172: "Lunar Cycles"

Postby jgh » Fri Jul 05, 2019 6:57 pm UTC

Reminds me of when every computer came with a Biorythms demo program.

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GlassHouses
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Re: 2172: "Lunar Cycles"

Postby GlassHouses » Fri Jul 05, 2019 8:40 pm UTC

jgh wrote:Reminds me of when every computer came with a Biorythms demo program.

Yeah, they were everywhere for a while, weren't they? I wonder why that was. Did anyone ever actually believe in biorhythms, like some people believe in astrology, or was it simply because this was something that was brain-dead simple to program on even the most basic devices?

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da Doctah
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Re: 2172: "Lunar Cycles"

Postby da Doctah » Fri Jul 05, 2019 8:41 pm UTC

In my country, "Pork Moon" is called "ham".

gcgcgcgc
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Re: 2172: "Lunar Cycles"

Postby gcgcgcgc » Sat Jul 06, 2019 8:00 am UTC

I believe the usual cycle is

Supermoon - > Hypermoon - > Ultramoon - > Adolescence -> Self-replication into many smaller moons, some of which will detach from the gravitational field of their host planet and search for a new host.

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Ken_g6
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Re: 2172: "Lunar Cycles"

Postby Ken_g6 » Sat Jul 06, 2019 3:58 pm UTC

Pork Moon: The only time when spending billions of dollars on the Space Launch System to get to the Moon, instead of using the much cheaper Falcon Heavy or waiting for the BFR, makes sense to anyone except congresspeople. :mrgreen:

ijuin
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Re: 2172: "Lunar Cycles"

Postby ijuin » Sat Jul 06, 2019 7:48 pm UTC

Falcon Heavy only lifts 64 tonnes to LEO. A crewed lunar landing would require a full launch for the Artemis lander, one for the trans-lunar injection stage, plus a launch for the Orion or lunar-capable Crew Dragon with extra Service Module fuel.

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orthogon
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Re: 2172: "Lunar Cycles"

Postby orthogon » Mon Jul 08, 2019 1:44 pm UTC

The title of this comic made me wonder about the design of a lunar cycle, i.e. a bicycle designed for use on the Moon. So far I've thought of the following:

- Weight would be less of an issue than on Earth (I'm ignoring the problem of getting it to the Moon in the first place).
- The absence of air would mean that higher speeds were possible (assuming a good cycling track had been installed) so higher gear ratios might be needed.
- On the other hand, you'd be riding the damned thing while wearing a space suit, which might limit your performance.
- Conversely, the low-gears might not be needed as cycling uphill would be much easier. With terrestrial gears, you could cycle up much steeper hills, but there would be the problem of stability (not falling off backwards) and of getting enough grip (not slipping down backwards).
- One difficulty might be keeping the front wheel on the ground (even on the level), since the "thrust" from the back wheel would be similar but the weight would be one sixth, so there might be a tendency to unplanned wheelies. A longer wheelbase or more weight up front might be needed. Perhaps even a front-wheel drive arrangement would be necessary.
- The handling would be different - the rider would have longer to make the micro-corrections needed to keep upright against the weaker gravity. Would this make it easier to learn?
- Conversely, cornering would require bigger movements - more lean would be required to develop enough moment to counter the centrifugal force at a given speed and curve radius.
- I can't work out whether inducing the lean would be harder or not - I know you have to steer momentarily the "wrong way" to get the bike to lean, but I'm not sure how much of a role gravity plays in this process or whether it's pure kinematics.
- I guess you'd need to do something to increase the tyres' grip since the force between tyres and ground would be less.

(I'm sure somebody has worked this all out already, but it's more fun trying to think it through from first principles than just googling it).
xtifr wrote:... and orthogon merely sounds undecided.

ijuin
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Re: 2172: "Lunar Cycles"

Postby ijuin » Mon Jul 08, 2019 2:32 pm UTC

Tyres should also be silicone instead of rubber, since vulcanized rubber does not handle vacuum or temperature extremes sufficiently well for the lunar environment.

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PM 2Ring
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Re: 2172: "Lunar Cycles"

Postby PM 2Ring » Wed Jul 10, 2019 8:54 am UTC

Your lunar cycle will also need to deal with the dreaded moon dust. It's much grittier than earth dust, since it hasn't been eroded by processes that polish off the pointy bits. It contains very fine particles, so it gets everywhere, and due to the lack of water it's chemically harsher than typical earth dusts.

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Re: 2172: "Lunar Cycles"

Postby markfiend » Wed Jul 10, 2019 10:25 am UTC

mschmitt wrote: scary bright

Ooh thanks for that. I've read the "Inconstant Moon" story many years ago and had forgotten what it was called (and who it was by!)
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ijuin
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Re: 2172: "Lunar Cycles"

Postby ijuin » Wed Jul 10, 2019 3:17 pm UTC

PM 2Ring wrote:Your lunar cycle will also need to deal with the dreaded moon dust. It's much grittier than earth dust, since it hasn't been eroded by processes that polish off the pointy bits. It contains very fine particles, so it gets everywhere, and due to the lack of water it's chemically harsher than typical earth dusts.

A good point—this means that the gearing and chains will need to be in an enclosed housing as well to protect them.

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Re: 2172: "Lunar Cycles"

Postby Vroomfundel » Wed Jul 10, 2019 7:13 pm UTC

orthogon wrote:Perhaps even a front-wheel drive arrangement would be necessary.


Front-wheel drive is not a good idea, even more so on the moon; it will tend to slip easily. The same forces that cause the spontaneous wheelies also increase the grip on the rear wheel. Front-wheel drive on a bicycle will be as efficient as its rear break i.e. not much.
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GlassHouses
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Re: 2172: "Lunar Cycles"

Postby GlassHouses » Thu Jul 11, 2019 1:34 am UTC

Vroomfundel wrote:
orthogon wrote:Perhaps even a front-wheel drive arrangement would be necessary.

Front-wheel drive is not a good idea, even more so on the moon; it will tend to slip easily. The same forces that cause the spontaneous wheelies also increase the grip on the rear wheel. Front-wheel drive on a bicycle will be as efficient as its rear break i.e. not much.

My bicycle has only a rear brake. I'm not going to claim that that arrangement is optimal, but I seem to be able to navigate traffic with it, at least without crashing into things on a regular basis, and so do millions of other people -- I believe the rear-wheel backpedal-brake setup is still popular, at least in the Netherlands, for being reliable and low-maintenance. And apparently effective enough for use in normal traffic.

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SuicideJunkie
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Re: 2172: "Lunar Cycles"

Postby SuicideJunkie » Thu Jul 11, 2019 4:41 am UTC

Rear wheel brakes won't stop you as fast, but also won't suplex you into the pavement if you push too hard.

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Pfhorrest
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Re: 2172: "Lunar Cycles"

Postby Pfhorrest » Thu Jul 11, 2019 4:53 am UTC

I once braked so hard on my old one-speed that I somehow bent the front wheel in a 90 degree angle. I don't pretend to understand how the physics behind that worked. Could have had something to do with cornering at the same time.
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Re: 2172: "Lunar Cycles"

Postby pogrmman » Thu Jul 11, 2019 3:26 pm UTC

SuicideJunkie wrote:Rear wheel brakes won't stop you as fast, but also won't suplex you into the pavement if you push too hard.

A bicycle with only a rear brake (not the pedal type, the hand type) is how I broke my first bone. I’m confident that it wouldn’t be happened had both wheels had brakes: I broke hard and it caused the front of the bike to fishtail, so I fell off.

Admittedly, I was going down a very long, steep hill beforehand, so I had a lot of speed. But I still think having both brakes would’ve prevented that.

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ucim
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Re: 2172: "Lunar Cycles"

Postby ucim » Thu Jul 11, 2019 3:44 pm UTC

For caliper hand brakes, the front is typically much more effective than the rear. Coming down a hill at top speed, I needed to brake hard to avoid a car pulling out. I ended up balanced on just the front wheel, between flipping over and not flipping over.

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Old Bruce
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Re: 2172: "Lunar Cycles"

Postby Old Bruce » Thu Jul 11, 2019 6:48 pm UTC

Put the bike inside a rugged air-tight big hamster ball.

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measure
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Re: 2172: "Lunar Cycles"

Postby measure » Fri Jul 12, 2019 1:14 pm UTC

Old Bruce wrote:Put the bike inside a rugged air-tight big hamster ball.

Put anything inside a rugged air-tight big hamster ball.


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