Massive engineering projects?

[GamePhil]

That's pretty much what I remembered. I just thought it was a total waste and dismissal of such a huge concept. The Dyson Sphere should have been the story, not a throwaway teleporter character.

I expect it was something they meant to use, but never got around to, in the same way as she wasn't meant to be a throwaway but was a character that just didn't work out.

[DocMan]

I expect it was something they meant to use, but never got around to, in the same way as she wasn't meant to be a throwaway but was a character that just didn't work out.

I think they changed writers or editors (or both) so they neve got back to the mystery. Then they dropped Lila because she was insufficiently popular.

Doc

[Sociotard]

I read about a city in south america that has smog problems, because they're in a valley, so the wind won't blow it away. They are proposing blasting a channel through the mountains to make a biiiiig crossbreeze. How nifty is that?

[Ternaugh]

A few projects:

The Transatlantic Tunnel: Imagine shuttling from London to New York under the Atlantic on a maglev train in a little under an hour. Of course, the tunnel has had the air evacuated from it so that the train can hit 5000 kph+ speeds.

For maglev info, try:
http://travel.howstuffworks.com/maglev-train.htm

For Transatlantic Tunnel info, try:
http://media.dsc.discovery.com/conve...teractive.html

And for a fictional, alternate earth treatment, try:
A Transatlantic Tunnel, Hurrah! by Harry Harrison (oop, though probably available used)

Floating Cities: These are large arcologies designed to travel on the oceans of earth. An early design, the Freedom Ship, is basically a huge ocean liner with room for 50,000 residents.

http://travel.howstuffworks.com/floating-city.htm

Laser Launch Facilities: Why burn reaction mass, when you can get the boost you need from a ground-based laser? Put the lasers in space, with large solar arrays, and you have a way to apply a push to ships without them requiring large amounts of reaction mass aboard.

Try The Mote in God's Eye, by Larry Niven and Jerry Pournelle for a truly powerful example. David Brin's Sundiver also mentions the use of laser rocketry, but in a less "hard science" manner.

Terraforming: Of course, Mars is the primary choice for terraforming, but why stop there? With a lot of work, Venus could be converted to a more habitable world. Or, how about restoring parts of earth ravaged by slash and burn, stripmining, and global warming?

JoeG

[Agemegos]

How about permanent shuttles? KSR had one in the Mars trilogy, I believe. A shuttle with all of the living quarters, life support and such is on a permanent Hohman transfer orbit between any two planets. Then you only have to accelerate the people to speed. All of your life support payload is already there.

I have been hesitating to reply: but I really don't think this is going to work. The Hohmann orbit has a definite period that cannot be adjusted and that is different from the period of either of the planetary orbits that it is tangential to. So it will shuttle back and forth between Earth's and Mars' orbits right enough, but Earth and Mars won't be there when it gets there. And it's not like you can get out and wait.

[keithcurtis]

I have been hesitating to reply: but I really don't think this is going to work. The Hohmann orbit has a definite period that cannot be adjusted and that is different from the period of either of the planetary orbits that it is tangential to. So it will shuttle back and forth between Earth's and Mars' orbits right enough, but Earth and Mars won't be there when it gets there. And it's not like you can get out and wait.

I probably misremembered the orbit type. It's been a while since I did any reading in that area. However, many Sci-Fi authors and engineers have proposed this idea, so there is probably some kind of trajectory that will work. KS Robinson's a pretty savvy fella.

Keith "How about engineering a Smoke Ring--on purpose?" Curtis

[Agemegos]

I probably misremembered the orbit type. It's been a while since I did any reading in that area. However, many Sci-Fi authors and engineers have proposed this idea, so there is probably some kind of trajectory that will work. KS Robinson's a pretty savvy fella.

Well, I must say that I find that remarkable. The only way I can see it having a chance is using a gravity slingshot at each end, and thus consisting of segments of two different solar orbits, and even so… Earth's and Mars' orbits only conincide in any given way once every 780 days, so if there is a trajectory to get you from here to there its launch window only recurs about once every two years. If this transfer orbit is to repeat its cycle it needs a period of 780 days. Travel time might well be assymetrical, of course, but this does imply a much longer average trip: 390 days each way instead of 259 in the Hohman orbit.

Of course you aren't aiming for a bitangential orbit, so you could just calculate a new interception orbit for each pass: you'd need to manoeuvre at each periapsis anyway. It all gets much too hairy for my rudimentary knowledge of Lagrangean mechanics.

I'd like to find out the charcteristics of this orbit: can you give me any sort of hint about where I can find a study about it?

[Agemegos]

I'd like to find out the characteristics of this orbit: can you give me any sort of hint about where I can find a study about it?

It's okay, I found them. The orbits are called 'cyclers'. They depend on using Earth's gravity (and sometimes rockets) to put the shuttle into a different orbit for each repetition: which is pretty gung-ho stuff. How do people find those solutions?

[Dr. Anomaly]

Keith "How about engineering a Smoke Ring--on purpose?" Curtis

That'd be massive, all right, but a bit beyond the scope of what was asked for, don'cha think, Keith?

[keithcurtis]

That'd be massive, all right, but a bit beyond the scope of what was asked for, don'cha think, Keith?

Sorry, got carried away. What about this wheel thing? Sounds terribly complicated.

Keith "and what color should it be? "Curtis

[Dr. Anomaly]

Sorry, got carried away. What about this wheel thing? Sounds terribly complicated.

Keith "and what color should it be? "Curtis

Forget the complexity...just how many leaves is it going to cost?

[LordZarglif]

What is a Smoke Ring? I know that it's a book by Niven, but what is it?

[Worldmaker]

Try finding Bigger Than Worlds by Larry Niven. I think it was most recently published in Playgrounds of the Mind

[Intrope]

What is a Smoke Ring? I know that it's a book by Niven, but what is it?

it's a ring of gas (in the book, breathable) in a close orbit of a neutron star.

The way this came about (if I remember the book correctly) is that the original star system had only two things in it: the primary star (Voy, I think is what it was called) and a gas giant in a very close orbit (like Mercury). When the star went (Super?)Nova, it left behind a neutron star. It also stripped a lot of gas of the gas giant, but not all the gas was blown out of the system; a good bit of it would come back over time. The result: in the orbit of the core of the gas giant, gases of various sorts collected. Eventually, the center regions of this torus around the neutron star had so much gas in it, that the pressure was about earth normal (but only in the center of the torus).

In the book, the smoke ring is inhabited by native life forms evolved to live in an earth-like atmosphere with no gravity. The humans in the story are descendants of a colony ship (they actually rebelled against the ship's AI, which lurks around trying to extend the neo-fascist/communist empire of the State to the smoke ring. So far, no luck...)

To get back on topic, I can't really see how you'd make a smoke ring until you're pretty close to being able to build a ringworld (nor why you'd want one).

[Mentor]

Arcologies and artificial islands are also great concepts resulting changes in terms of the cultural changes just as would the orbital or zero G habitats.