a wrap around space station

[why06]

I we made a space station that wrap around the entire circumference of earth would it stay in orbit forever<br /> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[inventorwannabe]

No. You need a techniqe to trace trends and compensate for misalignments. If You do it right - no problem! Have You thought about how to create gravity around the station? It depend on the speed which leads to calculations on the strenght of the station!<br /><br />Brgds / InventorWannabe

 

[Boris_Badenov]

While I think it might be technically possible, I question the need. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[qso1]

I'm not even sure its technically possible but as you pointed out, what would it be for? There is one possibility, something that large could get much of earths population off planet without having to go to the stars should some emergency require it. However, that solution is probably centuries away from being possible or practical. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[owenander]

would space elevators be possible using it as the anchor?

 

[qso1]

Without doing some research, I don't know the answer to that one. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[annodomini2]

<blockquote><font class="small">In reply to:</font><hr /><p><br />I(f) we made a space station that wrap around the entire circumference of earth would it stay in orbit forever<br /><br />Not without help. It sounds like you are describing something akin to a Ringworld, a space station in the form of a torus that completely encircles the Earth, right? If so, it could not stay in geosynchronous orbit without eventually losing stability. This was worked out mathematically by MIT students at the 1970 World Science Fiction Convention after the publication of Larry Niven's science fiction novel, Ringworld. Even the slightest deviation in it's orbit around the Earth, where one part of the station was slightly closer to the Earth than another, would cause a disequilibrium that, unless compensated for artifically, would result in the satellite orbiting more and more off-center, until it finally collided with the Earth. There's a technical examination of this at this website:<br /><br /><hr /></p></blockquote>>http://www.ghg.net/redflame/peter/ringworld.htm<p><hr /><br /><br />Going from OwenAnder's post, theoretically if you had a material strong enough you could hold it in tension with sufficient ties it wouldn't need to move.</p> <div class="Discussion_UserSignature"> </div>

 

[nexium]

I don't think GEO is necessary, except for useing a space elevator for constuction. The circumfrence would be almost three times that for LEO. With presently available materials we would need to think about 1000 tons per mile and that might allow an internal atmosphere of only one millibarr. Artificial gravity of useful amounts likely is not possible even with CNT with optimistic specs. Neil

 

[annodomini2]

I'm looking at this from a theoretical standpoint not an engineering one.<br /><br />1. No it wouldn't move as with the cables in tension at opposing points around the earths surface, like a spoked wheel.<br /><br />2. No it doesn't need to be in geostationary orbit as all sides of the ring need to fall, think of an arch that runs the full circumference of the earth. <div class="Discussion_UserSignature"> </div>

 

[Boris_Badenov]

I think a space elevator has to be up aound 66 thousand miles to work properly in relation to the Earths gravity. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[annodomini2]

<blockquote><font class="small">In reply to:</font><hr /><p>I'm having difficulty visualizing what you mean. How would any object NOT in motion about the Earth stay up? What would stop the Earth's gravity from pulling it down? And if it's not in geosynchronous orbit, how would space elevators work if the Earth's surface was not stationary relative to the object in orbit? <p><hr /></p></p></blockquote><br /><br />Lets say for theories sake that the earth is a uniform sphere (i know it isn't).<br /><br />If you were to have a uniform ring with uniform mass and excluded other gravitational objects from the equation (I'll come to this later), then that ring has a diameter of that of the earth plus 100miles * 2 for the altitude.<br /><br />The ring requires no rotational velocity as gravity acts upon all points of the ring in opposing directions, cancelling the action.<br /><br />Now bringing in the other gravitational objects is where the tethers come in, these retain the position relative to the earth in the same fashion as the previous concept, but for this there must be rotational velocity as the tethers are relative to mounting positions on the earth.<br /><br />Am I making sense now? <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[Boris_Badenov]

The Earths gravity attracts from all directions at the same time, clever. Would that really work? <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[annodomini2]

<blockquote><font class="small">In reply to:</font><hr /><p>Now bringing in the other gravitational objects is where the tethers come in, these retain the position relative to the earth in the same fashion as the previous concept, but for this there must be rotational velocity as the tethers are relative to mounting positions on the earth. <br /><br />Yes, I think I understand what you mean now. The space elevators would also act as tethers, so that the ring space station could not shift it's position off-center in relation to the Earth, correct? <br /><br />But of course, it would therefore have to be rotating, because the Earth rotates. <br /><br />But I doubt if any substance, even carbon nanotubes, would have the tensile strength needed for the job of keeping a space station that would probably have a mass in the megatons, if not gigatons, stationary. <br /><br />If you were to have a uniform ring with uniform mass and excluded other gravitational objects from the equation <br /><br />Except that you couldn't exclude other gravitational objects....there's the moon and sun and the other planets....all of which would be tugging at the space station from different directions. <p><hr /></p></p></blockquote><br /><br />That is the reason for the tethers, if you were to use 2 tethers at each point offset at angles of say 15deg or something, the tension between these 2 points would maintain 'vertical' position relative to the poles/centres of rotation and also 'horiztontal' position relative to the axis of rotation/equator.<br /><br />Yes it would have to rotate and probably need to be in geosynchronous orbit to allow for easy assembly.<br /><br />But as you have said the challenge to making something like this is a material light enough and strong enough to do the job.<br /><br />I believe there will be something at some point as many scientists appear to be losing confidence in CNT.<br /><br />But until then we shall see, the other option may be to remove the tethers and use some kind of propulsion <div class="Discussion_UserSignature"> </div>

 

[scottb50]

That may apply for very small particles, but a solid structure would be pretty much static. Why you would want to this is another thing. The only problem I could see is gravity differences pulling on one section and not others. <br /><br />The biggest problem I see is putting that much structure into orbit to begin with. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

That's what I was saying, you could build it strong enough if you needed to. I just thing the possibility of putting that much mass in orbit to do it is beyond capabilites or needs. <div class="Discussion_UserSignature"> </div>

 

[annodomini2]

I know, I was saying from a theoretical standpoint.<br /><br />Although to add another concept to this idea, if you were to make the ring controllably flexible in some way.<br /><br />For example, to get it into orbit with current technology it would have to be in sections.<br /><br />So if we took a train carriage as an example and added cylinder struts to which we could extert force on the adjacent modules to maintain a certain level of tension, this theoretically would allow us to adjust the tension according to the force applied. <br /><br />Also due to the possibility that this may not be the case if the forces do achieve a state where the system would break up as the initial design is modular the systems can be designed such that if forces exceed design tolerances the modules can be allowed to seperate preventing damage to the system.<br /><br />The tension system may allow a reduction in energy usage to maintain the orbit, but the flexibility to prevent damage to the system.<br /><br />Opinions please? <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[barrykirk]

Sounds to me like a combination of a suspension bridge and an arch bridge.<br /><br />The ring would be under compression, not under tension.<br /><br />Offhand, I don't know of any material that would have that kind of compression strength.<br /><br />The cables could be stationary and would hold the ring<br />in place, kind of like a suspension bridge.<br /><br />Interesting concept, but probably not possible.<br />Gravity wouldn't be a problem since anybody on the ring<br />would experience almost 1 G at all times.

 

[nexium]

About 500 kilometers is minimum altitude, otherwise you have large air friction losses which need to be made up unless the structure is made of something much stronger than CNT = carbon nano tubes. If the structure is slightly faster or slower than orbital speed, it will have a bit of gravity, but likely not enough to be useful. If space elevators provide access to Earth's surface, the altitude of the ring needs to be slightly above GEO stationary altitude. CNT is elastic and many other substances are quite plastic = adjust the shape under stress, so the minor differences in Earth's gravity, require only a bit more strength than a reasonable safety factor without considering gravity fluctuations. As others posted the gigatons of material required are far beyond present and near term technology.<br />Forever is a very long time. The ring would likely be beyond ecconomical repair after a few centuries, and it would need to be speeded up annually or oftener to avoid increasing stress as it slowed down. Neil

 

[why06]

Bringing this subject back up... I don't see that the balance problems will be that big an issue especially considering the same thing goes on with rings around planets.<br /><br /><br />It would seem that attaching space elavators to the Ring would form adouble purpose of suspension and a supply line. <br />The orbiting world can be created over time so that by the time Earthlings sart civilizing other planets an external docking port will have been created to surround earth.<br /><br />The moon is always a substitute but it is not as good as Earth.<br /><br />any thoughts... <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[why06]

We can use old external fuel tanks connected by carbon-nano tubes. <br />-We could generate enough energy to power all the Earth<br />- It would provide a spaceport large enough to begin full scale buissness opertunities.<br />- We can make it along and along. <br />-As we build the first space elevator. Production would Quadrouplify.<br /><br />I will look at some sites and maybe read "Ringworld" and see if I can come up with an easy way to do this. <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[why06]

That's true....<br /><br /><br /><br /><br /><br /><br />But teathers might stabalize the object.<br /><br />It will be composed of In dividual space station connected by carbonanotubing. We will need at least 4 than 8 to create a octagonal shape. <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[nyarlathotep]

The major issue that I see is that should the pellet loop jam or for any other reason fail, which it most certainly will, the station is going to have the energy of a very large hydrogen bomb when it hits the ground. So every month or so you are going to detonate the station and the multi-billion dollar accelerator under it. <br /><br />Lofstrom's launch loop tries to solve the "inevitable catastrophic failure wipes out the ground station" problem, but how the hell do you construct a 100km tall vacuum tube required to enclose the pellet stream on an incline? This is an even bigger materials problem than the space elevator.

 

[peace_maker]

sounds like deep space 9 on star track

 

[why06]

I said to do the elavator <img src="/images/icons/rolleyes.gif" />.... <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>