OT: About Space Elevators
 

Just FYI since we've discussed adding Space Elevators to the game, you can get a huge amount of information about how practical it would be to build one for Earth right now by visiting www.highliftsystems.com -- especially the downloads sections where lots of PDF and Word files are available with technical information.

Re: OT: About Space Elevators
 

What happens if the Space end of the ribbon breaks Geosynchronus orbit by whatever unknown reason even for a second?

And what happens if the Ribbon breaks?

And will it be accesable to everyone?

Three reasons Why I don't like the idea of a space elevator.

Re: OT: About Space Elevators
 

I got a friend who's always taking about this, and I just don't get it. How is it better that launching things.

I may be a dense old chemist, dregeing up high school physics but, isn't the energy needed the same no matter how you achieve orbit? How do you adapt the terrestrial end to things like chanes in the earth's surface due to tidal forces. How do you maintain something that long. Doesn't air resistance still affect things on their way up?

I want simple questions like this answered before I wand through a bunch of plans.

[ October 09, 2002, 00:39: Message edited by: Arkcon ]

Re: OT: About Space Elevators
 

Will it survive a colision with a fully laden 737?

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">It's quite simple actually. The amount of energy to get X tons into space is the same, but the energy can be generated on the planet, or in orbit, and transfered to the elevator through the cable itself. The elevator can have a realatively small and simple electric motor and receive joice form the cable. So you don't have to carry the fuel in the vehicle going up.

The weight of the fuel in a conventional orbital launch vehicle is a great majority of the total weight of the vehicle. And the more fuel you have, the more you need to carry the fuel, and so on.

Tidal stresses, air resistance, and other things are serious problems. Coming up with materials and designs that can handle those loads is the main stumbling block to acheiving something like this.

<font size="2" face="Verdana, Helvetica, sans-serif">It won't go flying off into deep space if that's what you are asking. The cable doesn't hold the orbital vehicle down. In effect the sattelite/cable combo beceoms a verry long sattelite circling the earth over one spot, which it just happens to touch.

If it breaks, it would likely be a bad day for anyone that happens to be where it decides to land. That danger would likely be lessened greatly by the location chosen. They would put it where if it did fall it wouldn't land on populated areas. It wouldn't even have to be over water, although that would be safest. Given a likely altitude of the orbital end of 250 to 300 miles. There are some over land areas that would be safe.

And is any space travel accesable to anyone? But the costs invovled in this would be so low it would make orbit within reach of many that have no hope now.

<font size="2" face="Verdana, Helvetica, sans-serif">Is that supposed to be a joke? No, it won't. But what will? Not much. But if it were the target of a terrorist attack it would likely be very expensive in terms of cost, but not nearly so in terms of lives lost as the World Trade Towers.

Geoschmo

[ October 09, 2002, 01:08: Message edited by: geoschmo ]

Re: OT: About Space Elevators
 

Actually, to rephrase my question:

What happens to the people/goods that are on the ribbon if the Space end of the ribbon breaks Geosynchronus orbit by whatever unknown reason even for a second?

And also, they wouldn't make a ribbon out of fabric; will there be some kind of massive whiplash?

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">The elevator itself would most likely have some sort of parachute recovery system. That's not a big deal wieght wise or technologically. We can do that now. A much bigge concern is what would happen to the ribbon itsself, or more precisley anyone it falls on. No matter how light it is, 300 miles of it is going to be heavy.

Re: OT: About Space Elevators
 

Instead of asking these questions here you should visit the site and you'll find the information. That's why I posted the site. Nevertheless, I'll try to answer some of these questions.

The Space Elevator is basically a very long cable that stretches from a space station in geosynchronous orbit to the ground. The point of ground contact must be very close to the equator, of course, and that limits where it can be setup.

Although... there has been talk of using some fancy engineering to make 'diagonal' cables from temperate lattitudes meet several hundred miles up and then connect to the single cable coming from the large station in geosynchronous orbit. Once you got it setup it would work as well as the single cable system. The problem is in setting it up! http://forum.shrapnelgames.com/images/icons/icon7.gif

There are several reasons this is an easier way into orbit than rockets or other launch vehicles. The first is simply that you don't have to push so hard to go up! Heating thousands of tons of gas to very high temperatures by combustion so they will bLast you upward in the process is very inefficient, not to mention dangerous. With the space elevator you could have an electric motor more-or-less like those on current elevators in high-rise buildings. Or perhaps a 'pneumatic tube' type system with the air being pumped up to the station serving to propel the elevator as well! http://forum.shrapnelgames.com/images/icons/icon10.gif Anyway, not having to gain speed by 'throwing' stuff away from yourself at high speed is both more efficient and safer. If the elevator cars are 'external' to the cable then you also have to deal with air resistance but this is better with the cable than with rockets as well. You also don't have to go for super-sonic speed right away. Obviously it will be a long ride into orbit if the whole trip is at standard elevator speeds http://forum.shrapnelgames.com/images/icons/icon12.gif but it's best not to go more than a few hundred miles an hour for the first 50,000 feet or so. After that you can go thousands of miles an hour with no major air resistance problems. Not having to fight the atmosphere or design for the heating from friction makes the elevator cars much cheaper than rocket vehicles. If the elevator will be inside the cable (more difficult but we'll probably do that eventually) then you could evacuate the air and use the 'pneumatic tube' effect as I mentioned before.

The possible accidents and problems are many of course. If the cable breaks somewhere up in orbit and loses 'equilibrium' so that it comes down, it will cause damage across hundreds or thousands of miles of terrain. It's got to be made of incredibly strong materials so it will probably destroy anything it comes down on, crashing at orbital speeds. If the whole cable comes down it would wrap almost all the way around the earth!

The 737 question is not such a problem as you might think. A modern jet airliner is basically a huge aluminum ballon. It's very fragile and the cable is very strong. An airliner would be sliced up if it hit the cable but probably do little damage. More dangerous would be a hit on the ground link where an explosion and fire might damage the anchorage. I think the elevator 'cars' will be far more vulnerable than the cable itself. They cannot be heavily armored without increasing costs quite a bit. They are rather similar to jet airliners in that respect! A small bomb could punch a hole in one when it's part way up and expose everyone inside to the vacuum of space. This could be at least as tricky to guard against as it is for airlines since explosives have become so high-tech and difficult to detect.

The station in orbit is pretty safe actually. You can use it as a launching point for ships headed out from earth and they will get a good boost, but the station itself will not 'come down' any more readily than a station without a cable. Obviously, if something grabs the cable and pulls it out of orbit you've got troubles. But that would take a lot of force. It's got to be a large station to anchor the cable and make the 'center of gravity' of the whole assembly rest in orbit. Hundreds of thousands, if not millions, of tons. There has even been talk of trying to capture an asteroid and use it as the counter-weight. That's a whole other mega-engineering project. We can worry about that after we've got at least one working cable... In the meantime we'll probably mine the moon for the bulk of the station material.

The issues of who would get to use it, and what it would be used for, are actually more serious than the engineering questions. It looks like we've got a material that can be strong enough to make the cable (Carbon nano-tubes). Everything else is known technology. But once it is built what effect will it have on the world? That's a very different problem than the technology.

[ October 09, 2002, 05:06: Message edited by: Baron Munchausen ]

Re: OT: About Space Elevators
 

Here is my problem with it. This cable needs to be what, 15 miles at the least? They plan to also put this thing on a floating platform in the ocean (for logisitical reasons to remove stress on the cable).

Suppose the platform gets caught in a hurricane, or even just a small squall.

I can see that big platform going "SQUEEEEAKKK SQUEEE-SQUEEAKKK!!" followed by one hell of a "POP! PING! SHSHHRHRHHHHRAAAATCH!" and then that cable is going to come down nice and fast and make one hell of a splash/dent (depending on location.)

Re: OT: About Space Elevators
 

Actually, it is more like 100,000kms long. You can learn a lot by just the FAQs posted at the website Baron posted. I still think something like this is far in the future...

[ October 09, 2002, 05:16: Message edited by: Captain Kwok ]