Bill Phil

I think Orion can do LLO. Not sure, however. The Apollo CSM was likely over engineered for its ultimate purpose.

Good luck, man. Hope it goes well, or at least improves on the long term.

I'm not arguing with the listed values. Just saying that I wouldn't trust them (weight growth).

Ah, but the moon systems of the giants and their Trojan asteroids provide even more material for exploitation, without mining planets. Although some of the moons are pretty close. And, for a settlement that is proposed, most of the mass (more than 90%) is shielding. That can be just about anything. Heck, hydrogen from a giant planet might suffice, if you can recover the energy costs by fusing some of the hydrogen you acquire.

I wouldn't trust the ITS numbers. But even beyond that, the square cube law may provide some of the difference. The area (thus some of the structural mass) shrinks at a different rate than the volume (thus propellant mass), and so a larger tank doesn't need much more structure. For example, the modern Atlas V first stage has a mass ratio around 14.5, compared to the huge Saturn V first stage (S-1C), that had a mass ration of around 16.9. Keep in mind advances made in materials since the 60s, and the Saturn V first stage even had fins...Of course they each do different jobs, but a large part of that difference is likely attributable to sheer size.

Sure, but so much energy is involved, and there's so many resources on lower gravity moons, that planets aren't that worth it. Of course, if you have enough energy to travel between stars, then mining out uninhabited planets isn't that hard. OP: Yeah, asteroids are good for resources, but they usually don't make good settlements. A bunch are just piles of rubble, and they can't handle too much rotation if you want to keep gravity around. Sure, you could just spin a cylinder inside and not the whole roid, but then you might as well just start mining the asteroid and build the settlement near it. Not to say that there won't be colonies inside asteroids, or that it's a bad idea. The asteroid can provide ample shielding, as you mentioned. You don't even need to use an engine to move things around. At least not on the cargo vehicle. A good EM catapult, imparting just a little velocity, and aimed towards a "catcher" or something, will suffice. If the colonies are close to each other, you can even run a "train" between them.

Yeah, sure, they proposed a crewed version... which was also scaled up by at least 165%.

Man. If you weren't looking for a specific image I would totally recommend any space scene from 2001: A Space Odyssey. Say what you want about the movie, but it had great space scenes.

I probably do get it, but due to the nature of the internet, it's impossible to tell.

Stargate SG-1. I'm watching it right now, actually.

Favorite anime? Oh, that's a difficult one. I would say Cory in the House if I wanted to joke around, but I want to give an honest answer. Probably Trigun. Although it's pretty much tied with Cowboy Bebop.

If there wasn't any atmo we would go sideways from the launchpad. Luckily there's not much drag involved. Most losses while launching are from gravity. Steel? Why would you use steel? Aluminum is where it's at.

Yes. At some point keeping the end caps on the cylinder is pointless, so you make it a torus to save mass.

It has nothing to do with those statements because I was not addressing those statements. Your previous response had little to do with my original statement, which was about people moving to the colony, and not the logistical challenges of maintaining said colony nor the cost. I was addressing this statement: I was not addressing: My original statement was that people may decide to move to a space colony if life is better and space travel is cheap. After your response (which did not mention the logistical challenges of moving millions of people into space, only that it was improbable, which I agree with), I reiterated the premise of life being better in a space colony, and moved on to addressing the likelihood that life will not be better in a space colony for some time, and then agreed that sustaining a settlement is not cheap. I only addressed the motivations of the potential colonists to move to the colony, not the difficulty of sustaining said colony, or the logistical challenges of transporting the colonists. I was addressing the potential motivator to make people desire to move to a colony. Those challenges of said colony are not relevant. However, given certain conditions, migrating to space may become possible and potentially preferable. The likelihood of those conditions occurring is low, however. And, the logistical challenges of transporting millions of people are far less than the logistical challenges of building a colony that can support millions of people.

Again: "Provided life is better in whatever colony" That was the linchpin of the argument. Of course, life being better in a colony likely won't happen for a long time, if at all. Sustaining any settlement isn't cheap, even ones that aren't colonies. The only question is who will bear the cost: the colony or the original settlement. It's likely the original settlement.

Not really. A torus has a diameter much larger than the smaller cylinder's diameter. A cylinder has no such smaller cylinder. We can also nest smaller cylinders within Kalpana One for various purposes, as is proposed in the paper. A torus is very inefficient for shielding. You have to not only shield the "ground", but also the "walls" and "roof" of the smaller cylinder. In a cylinder, you only have to shield the ground and the end caps. The longer it is the more efficient it is. Once again, there are methods to counteract the instability of longer cylinders. A torus may be useful for smaller stations and settlements, but when scaling up the inefficiencies of the geometry become harder to handle.

Maybe economic incentives. Provided life is better in whatever colony and space travel is relatively cheap, then it wouldn't be hard to imagine people moving there. Maybe not a whole lot, but a number in the millions could be possible.

Hollow cylinders of length 1.3 times the radius or greater are not stable. However, cylinders are the best option when comparing living area to total mass, under certain assumptions. And even a longer cylinder can be kept stable by connecting it to another longer cylinder. Angular momentum cancels out and you get giant flywheels for some kinds of maneuvers. Only issue is that the bearings would need to be insanely strong. http://alglobus.net/NASAwork/papers/2007KalpanaOne.pdf The link above is a paper on the Kalpana One design for an orbital space settlement.

It has nothing to do with mindset. There are plenty of people willing to do many things for money. To some, that includes staying isolated for years at a time. If you can't support a base as far away as Mars you have no business trying to build a colony there. Remember, a colony will be, for all intents and purposes, identical to a base for at least the first ten to twenty years or so, maybe more. Sure, you may have a hundred or so "permanent residents", but you will likely have plenty of transients doing science there who will ultimately desire to return home eventually. I'm thinking something like McMurdo Station, but with longer transit times and maybe smaller.

L-2 =/= Lunar Orbit The Delta-v from L-2 to useful targets is low. As a fuel depot, it would be best. Currently there are "plans" to use SLS flights to "refuel" DST. DSG will probably evolve into a depot over time. Gotta start somewhere.

It's not that far for a base at all. Even if it is, though, then that immediately rules out a colony. If it's too far for a base, it's much too far for a colony.

Neither. No celestial body yet discovered is truly suitable for colonization. Now, if we're talking about Mars or Venus being the only choices...? I'd prefer Mars, but Venus would make better sci fi. You're also forgetting Delta-v to return. Taking off from Venus and entering a low orbit would take many km/s of Dv. Mars is just 4 and some change to orbit, not to mention the lack of a significant atmosphere can allow us to use EM catapults to take off. The most I can see in the near future is bases on Mars, with bases in the Venusian sky eventually. Maybe colonies in the far flung future, but that's the far flung future.

You can send more payload to L-2 than to TLI. Thus, pooling resources at L-2 could be beneficial for Lunar activity. I personally think the DSG plan is a good idea. We really have no experience for long term space flight beyond LEO. Gaining that experience is a good idea if we desire to go to Mars. Also, I think NASA is underselling DSG's size, or at least not planning for the future in a realistic way. There will likely be at least two (if not four, SLS, FH, NG, and VH) LVs that will be able to service DSG. Maybe some Bigelow modules could find their way there, too. LOR was chosen for Apollo to minimize time, and, to an extent, mass to TLI. If I remember correctly, DSG as currently proposed is a mobile station. Maybe it could deploy landers in LLO and wait for them there? But that's just speculation.

I would love to see a reference to Thunderchild from War of the Worlds (this is technically a war of the worlds...) Maybe Donnerkind, which is German for Thunderchild, but we get to put a "k" in there. Of course I am in no position to request anything. I really like this story, it's very well done.

Nukes in space are just radiation sources. Albeit a huge amount of radiation. Could vaporize the roid, but that's a stretch. You'd be better off just pushing it with an Orion than blowing it up.