timmy wrote:Want me to re-check your calcs?
I haven't actually done calcs but make a big circle with one hand and a straight line with your other hand as it lets go... I really think it will work just fine. The biggest risks of impact with the the habitat itself would come from the mirrors, and maybe any other large protrusions on the hull, but not in a straight line. It'd be cuz of the Coriolis effect. But given the huge size here the protrusions would have to be big too... so yeah the mirrors are a maybe but I don't think hull hugging trains would, nor other spacecraft launching off the side.
The mirrors are in a very predictable location, of course, and so is the trajectory of any tangential launch, so preventing that, if needed, is as simple as doing the math and finding the launch (and attachment, for going the other way) points that are dangerous and prohibiting their use. Tangential launches are great for inter-hab transit - it is reasonably fast (within about an hour, you can get from anywhere to anywhere in a cluster that houses one billion people, in about an hour.... and if aligned right, you might get to other similarly large clusters in the same time!), reasonably safe and very cheap. You let go of one rotating cylinder. You have speed from this in a straight line. If you keep the others aligned right - which does take a little station keeping as the years go by but you're probably doing that anyway - you just grab on to the destination when you arrive. When you get there, just like you were parked on the launching hull... you'll be parked on the destination hull. Just hook on and done.
But yeah, in the space habitat cluster, transportation can be cheap and fast.
What about inside the habitat though? Since there's ground, water, and air, it is more like earth - transportation is going to be different. Here's the cool thing though: space *is* there, right under your feet. That's how we get to hull hugging subways.
Here's an interesting fact though: with the lower speeds and increased numbers of stops, going 20 miles to the other side of the habitat might take just as long as going 1000 miles to the other side of the cluster. That could be some fun to think about.
Anyway though, you'd go into subway stations and board a train. We could do all kinds of layouts here, but the way I like it is to have rings and lines on the habitat.
The rings have six stops, two for each of the three populated strips (and skipping over the three unpopulated strips - the windows / lakes) along the circumference of the cylinder. This means any place along this ring is like 5-10 minutes walk from a station. Or they could have three stops, if there isn't enough demand to justify more.
The lines go lengthwise and are really more like a loop. The number of stops would be demand again, but I'd kinda like to have a potential access point about once a mile - these access points would be useful for maintenance too, and perhaps the train need not stop if nobody is actually waiting/going there.
We can have a few trains doing each line if there's enough traffic to keep wait times low.
Anyway the way these work is they hang off the bottom of the hull. There's like abovehead rails to which the trains are attached and can use space wheels and safety connection cables, so if something breaks, you just hang on there. (Worst case scenario btw, everything breaks and the trains falls out into space... no big deal because there'll be rescue ships on standby anyway for all the other free civilian traffic, so they can just go out and tow it back. I'm going for redundancy rather than reliability: keep the trains and space cars simple and cheap, knowing that things can go wrong and it is OK cuz a rescue ship will be there if you can sit tight for 20 mins.)
I think a good speed here would be between 30 and 50 mph. About the same speed you might drive a car today. The distances aren't that long. They could be powered by a third rail or a small solar panel right on the train - one side will be pointing straight at the sun, 24/7, so that is reliable. The only energy needed is acceleration and making up for loss of friction on the wheel, and of course the people's convenience inside, so it isn't really much. I wouldn't even bother with stuff like life support, though it is technically a spacecraft, just because every few minutes it will make a stop and open the doors anyway. Just want enough reserve for accidents.
Why not have the tracks inside? We could, but benefits here are keeping the sound out (some will be heard from underground but I don't think it would be much if anything noticiable through the meters of ground), keeping the ground clear for other use, nobody will get hit by a train when it is outside, and speed could potentially be higher.
Besides tracks on the ground are sooooo 19th century. Well, ok, tracks inside are a good decision too and we can do it either way but this is cool.
So now we have a mass transit infrastructure that can get us from anywhere, to anywhere, remember this is a huge area too, with over one billion people living here and potentially over 100 climates etc.... in a travel time of two or three hours, at MOST, including stops and some delays. And virtually energy free in simple, low cost vehicles.
You live in NYC and want to visit LA? No problem, take a tangential shuttle over. One hour travel time at a small cost, it could very well be free, and you're there. You can make it a day trip.
Many of the benefits I've previously written about the Star Trek transporter here... but all hard science tech. Nothing we couldn't build today (if we were in space). Note btw: it need not be all mass transit, a private vehicle could do a tangential launch too, simple enough to be affordable and safe enough to be lightly regulated. (Not much different than private cars in the real world.)
How cool.
Now, let's go inside the habitat. If the mass transit system is as successful as I hope, we might not need so much of a road network. Roads are very useful, so I'd still want them, but we might be looking at a lot of single or double lane country style roads, with three or four lane roads being fairly rare. Just not that much traffic. The roads may even be shared, with cars and pedestrians together. If the residents opt in to snow, clearing can be simpler just because there's less that needs to be done! Also remember a ground car is going to be intra-hab only, but you could perhaps drive it into a ferry to go to another hab. That'd be interesting.
I love quiet roads. And green cars - if the max range you need is 50 miles, and max speed like 50 mph, that's to and from anywhere, round trip, in the hab, you can do electric without expensive batteries and super motors.
Here's some interesting implications of all this:
1) the space society might be kinda low tech. By simplifying the problems, we've simplified the required solutions, like with our simpler green car and these dumb spacecraft instead of advanced propulsion. Higher tech might just not get developed due to lack of demand.
2) with commuting being so easy, we might see a lot of economic specialization (contrary to the typical space bias of every little bit being 100% self-sufficient)
3) with all this traffic and access ports, illegal migration, smuggling, invasions, etc. can be more difficult to prevent than, again, the typical space bias makes you think. I guess they could close their borders and move away from the cluster if they really want to be isolated, but that comes at a cost. And, as I've actually written about before, criminals could try to get rid of evidence by just shoving it out one of the various airlocks...
I used to think of a commando raid on a space hab as involving them attaching and cutting their own hole to enter. But instead, they might just use an existing train station port. Of course, cutting your own hole has advantages too, but either way is fun. You could take a space fighter in through an automobile ferry port too. Imagine the surprise!
Oh well, I'd better stop rambling eventually. But bottom line: artificial habitats change the transportation landscape so much. Obviously for interhab transit, but it does for inside the habitat too, and the fun just never stops coming.