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> they just hand wave that all failure will happen on the moon side and never affect earth... um okay? Because of testing?

They don't handwave it, they calculate it. It's significantly less handwavy than your back-of-napkin objections.

Can you point to the specific section of the paper where this is calculated. I admittedly only skim read, but I did go through the whole thing, and I'm convinced I missed this kind of analysis somewhere.

A cable in geosynchronous orbit isn't a problem. Of course the problem is it won't stay there: the dynamics are likely to be interesting.

Now let's do some basic arithmetic. Moon is about 10^22 kg. Saying it will move as a result is like worrying that a semi will stop because of a fly.

If you hang a cable from your home ceiling with a little weight at the free end, what position do you expect the cable to stay? Why do you not expect it to stay down if you hang it on the Moon?

The cable in not in geosynchronous orbit, it's in geosynchronous altitude. If it is cut, it will fall into Earth.

Just to check, are you asking about a tiny cable on the surface of the Moon, or a 1-light-second-long cable where both ends are “the bottom” in local gravity even though they’re on opposite ends of the straight cable?

Oh, thanks, I see the problem now.

I imagine it would be nailed down at the Moon, even though it 's going "up" on that end too, the Earth end will very likely weight much more than the Moon and pull the entire cable. But the fact that it must be much fatter near the Moon does indeed complicate things.

> Wouldn't this cable greatly alter said orbit?

Only if it's extremely massive.

So a cable at 300,000km at, oh, I dont know, an average of 1 meter wide, is not massive?

I think scrapping together enough material on earth to build this will be the first problem.

2.36 x10^8m for rough cylinder volume.

Steel weight would be 1,864,400,000,000 kg. Yes itd be a hybrid material. So, half of that? Maybe a quarter? That's not an insignificant amount of material at a 1m diameter cable. We haven't even gotten to labor costs and energy required.

I get astronomically, its insignificant. But I doubt it's going to have no effect.

The moon weighs 70,000,000,000,000,000,000,000 kg.

That's 37,545,591,074 times your projected weight of the cable.

Is it valid to say this is the "weight" of the moon?

I would have assumed such measurements would deal exclusively with the moon's mass.

Are the two terms used interchangeably in this context? (honest question, I really have no idea)

I'm using them interchangeably here, but you're right, it was sloppy - I should have said mass. (They're only equivalent on Earth, and even there a given mass's weight changes based on where you are!)

> So a cable at 300,000km at, oh, I dont know, an average of 1 meter wide, is not massive

Massive to a man, not a moon...

No it would actually have no effect... Again your numbers are vastly out of scale.

"Let’s say such a line was made of a cable witha0=10−7m2: its total mass would then be around 40,000 kg. This is about twice the mass of the original lunar lander,and would make transporting and constructing such a cable completely plausible" -- From the linked paper.

> What if the cable attached to the moon and then locking the other end to earth orbit alters the month's orbit?

Sorry that's functionally just not possible. More so the moon is already moving away from the Earth at a couple centimeters per year. You're not even going to slow that down.

Your intuition is out of proportion, because astronomical objects are big. Really big. A spider riding on the left side mirror of a 18-wheeler has a better chance of drastically changing its course.