The Astronomy Thread

Cad

scientia potentia est
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According to wikipedia they are hoping to get the re-use time on the first stage down to < 24 hours. They are saying it should require virtually no refurbishment once they are "live". Thats fucking impressive if so.
 

khorum

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Automated refurbishment during those 24 hours is even more incredible.

The whole idea had always been a fleet of rockets and drone landing barges with a highly automated repair and refurbishment hubs to drive launch cycles down to weeks from months then down to days from weeks.
 

Sylas

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I thought the whole idea was to get material science to the point where we can build space elevators?
 

iannis

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the tensile strength is beyond our scope, and the tensile strength is the least of it.

That cable is going to wiggle. It's going to oscilate. It will very quickly become unstable and start to just whip the fuck around. Stanley overcame that problem in Mars with magic orbital AI's. But we don't have magic AI's yet. We don't have any AI's yet.

Even though the idea has been around for a hundred or more years, the engineering ain't there to actually do it. Who can say what the future holds, but the immediate future (50 years)... not so much.
 

Sylas

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I thought graphene basically solved the tensile strength problem, the problem was mass producing it? I mean I don't really know I thought we were much closer than 50 years away.
 

iannis

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They're starting to mass produce carbon filaments.. but yeah, it's not just even a problem of mass production. The yield for energy to produce them... you don't even have to do the math. You can just see that's not ever going to be practical without some world-changing innovation. You need a -lot- of this shit.

Now I'm not 100% sure about this part, but I think it's a consideration. There's also a scalar problem. You know how an ant can lift some ridiculous % of their body weight, one little ant carrying entire leaves around and shit. You blow that ant up to human size and she (edit: ants are she's) can't do it anymore and (it's been a while) but I think the reason for that is just simple geometry. The ratio of a2 b2 c2 never changes with scale, but the strength of materials sure as shit does. It seems like you'd run into a similar issue where you're taking carbon atoms strung together and trying to apply that to a scale of orbital mechanics. I might be retarded tho, but I do think that's also a real thing.
 

Khalan

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IM pretty sure they would also have to anchor the end into geosync orbit otherwise it would rotate at different speeds than the base, causing all sorts of problems. So we are talking 35,000 km above the surface of the earth.
 

khorum

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Well yeah, but we'd still need to get the CNT ribbon into orbit... even if we manufacture the graphene in orbit we'd still have to get the carbon up there. If we find an asteroid with carbon somehow we'd still need rockets to get the means to haul it into orbit and then get the equipment up there to manage it.

So yeah, we'd still need a commoditized rocket scene going.
 

Brad2770

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Tuco

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I don't think we'll be able to maintain a counterweight at 100,000km, keep it in a clean orbit and build a ribbon that is light and strong enough.
 

Tolan

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That's one of the big questions I think everyone has. Now that they've landed it, what will it take to make it launch-worthy again?

I have to imagine there are a lot of engineering decisions made to minimize weight based on the assumption a rocket is only used once. Having to reinforce everything so that it can be relaunched has to be expensive.
Why do you think there is a need for expensive reinforcements when the device gently accelerates and gently decelerates? Besides, aluminum is a relatively cheap material.
 

Cybsled

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Outside of doing it because we can, at some point these colonies will come and they are going to be all in and self sufficient ventures. All in on the biological side because after a certain amount of time entropy is going to set in and bones / muscles will weaken and who the hell knows what else. Self sufficient because well they'll fucking have to be when it takes so long to get supplies in from earth.

I'd be curious to see the ramifications of that. Will people born on Mars and live there for their childhood life be materially different? I'd certainly think so. Would they even be able to come back to Earth and function in Earth's gravity when they would weigh 2.6 times more? I know if I suddenly woke up weighing 520 LBS I'd be pretty fucked getting around.

Not something Sci Fi really touches much which I find interesting. I assume people would need some kind of Exoskeleton to visit Earth which would be sort of cool.
Actually, The Expanse on Syfy folds this into the narrative. People born out in the Asteroid Belt have a tendency to be taller due to lower gravity and they have trouble functioning on Earth due to the massive change in gravity. They actually use "gravity torture" against a Asteroid Belt person in one part and it is later revealed the legal way to deal with them on Earth is to place them into (I presume) zero buoyancy water tank.
 

Picasso3

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Why do you think there is a need for expensive reinforcements when the device gently accelerates and gently decelerates? Besides, aluminum is a relatively cheap material.
In an article later posted it said Elon has been insisent on reuse since day 1.
 

Tolan

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In an article later posted it said Elon has been insisent on reuse since day 1.
I know that. That doesn't translate into a need for expensive structural reinforcements. If it's strong enough to make it to LEO, it's strong enough to land in reverse.
 

Tuco

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Why do you think there is a need for expensive reinforcements when the device gently accelerates and gently decelerates? Besides, aluminum is a relatively cheap material.
There is nothing gentle about what that rocket did, and that rocket is in no way cheap.
 

Tolan

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There is nothing gentle about what that rocket did, and that rocket is in no way cheap.
Expense due to new technology development and (maybe) more on-board components has nothing to do with structural reinforcements, which was my point.

The G forces on that rocket are relatively low compared to many other engineering applications. Except for, perhaps, the shock of landing, which if fine tuned should be very benign, the reverse landing operation exerts similar G's as the launch.