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15:39
@ArthurDent i'm really looking forward to seeing that (even though i won't understand it)
 
1 hour later…
17:01
^ me trying to coax a really rather awesome engineer who listens a lot to The Space Show to come take a look at this tether issue.
 
3 hours later…
20:07
@ArthurDent actually the first asteroid is 7500 tons, and then they get bigger. not that that changes the point.
20:46
Ha, that would be cool if we could get some expert advice. Even without him, once i get this simulation up it should show us the orbital stability. Then we can apply constraints and estimate how much fuel it would take to keep it stable.
he's a NASA guy. it would definitely be cool.
John Powell?
no, John Fincannon. The guy who did a really elaborate analysis on John Powell's idea.
Looks like he was an electrical engineer.
OH DANG he went to A&M!
That's where I graduated
fine school :)
20:54
Have you ever read the book The Moon is a Harsh Mistress?
I bring it up cause you answered about not sending stuff from the Moon back to Earth. In that book they have a catpult that does just that. I'm curious how big such a catapult would have to be.
I guess it would be more like a railgun
I have not. i read the Wikipedia article about it.... i haven't read any fiction at all for 8 or 9 years
Not even scifi? That's interesting.
i already feel like i have an uphill battle when i say things will be so big and awesome, but i hear what you are saying
the lack of atmosphere would make it far more practical than the impossible designs for the Earth.
with the infrastructure in place, energy will be extremely cheap. with the option of railguns, coilguns, sling launchers - it seems that at some point transport will cease to be an issue
reentry would really be helped by being able to send things to a tether though, not straight into the atmosphere.
20:59
Yeah of course this would not be one of the first things to focus on. It might, however, make it easier to persuade people of the long-term benefits of lunar colonization.
You mean a tether that goes into the Earth's atmosphere?
yep, i hear you there too. in order to make the powerful argument, you have to show what happens in the long game
That would be incredibly more difficult than a lunar tether
no, it is an orbital tether that uses the same trick the lunar tether does, such that the speed it is moving above the surface is a lot lower than orbital velocity
Oh yeah. I think the biggest issue with something like that would probably be orbital debris.
At least given our current LEO situation.
yes, one of the nice things about it is that the tether itself is able to host a service that handles debris, and can do so much to make satellite launch cheaper, it has leverage to get people to put their satellites in orbits convenient for the tether
at the moment, the foot is 250 km above the surface and moving at 4.5 km/s
21:04
Yeah that's true. I think such a tether would be a great help. What sort of material could the tether consist of though?
The tension will be astronomical
yeah, in its case, it sort of needs those carbon nanotubes, or maybe graphene
Well once I get this simulation running, we will be able to figure out what the tension is
although if it was massive enough, our best existing materials aren't out of the question
And it would be trivial to apply it from the Moon to the Earth
do you think it would be possible to post that simulation somehow? can we add it to the repo?
21:06
Once I get it up, sure
It'll just be a matlab script
what i'd really love would be to put it on the website, like we've done for a couple of Hoh's programs
Making it look pretty will probably be more challenging than the physics itself
pretty can come later. this is for the engineers out there.
21:23
ugh I changed the frames to make the derivatives easier but they're still gross
 
2 hours later…
23:12
@MolbOrg i'm going to try to come back to this after getting some more modelling stuff done. i've been doing a lot of the philosophy stuff for a few days now.

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