Space Bridge: A Space Transportation Proposal

[PJay_A]

Proposal:

Launch a satellite into orbit. The satellite would feature equal detatchable halfs. Each half would contain equal loads of hundreds of miles of coiled nanocarbon cable attached as a single long cable. Once parked in orbit, the satellite would split and each half would detatch and unbearth, firing indepenpent thrusters, moving in opposite directions appart from one another at a safe slow speed, uncoiling the cable so that the cable connects, bridging the two now-independent satellites. The goal is that eventually the satellites will reach geosyncronous orbit all the while uncoiling the cable.

Because of the curvature of orbit, the middle point of the cable between the two satellites would be its closest distance from land. The further the satellites are from each other, the closer to Earth that midway point becomes. Let's launch with enough cable so that we can distance the two satellites apart enough so that the cable midway cuts through the atmosphere's "near space". On the ground, space travelers would simply float up via hot air baloon to near space at a docking port of the orbiting Space Bridge's midway point. From there, a cable car using electromagnet propulsion would take the passengers to either satellite in geosyncronous orbit. Eventually pressurized modules and docking ports for interorbiting spacecrafts could be added to the satellites.

Can this be done? I think it is much more realistic than the Space Elevator concept, and probably would be multitudes less expensive to build!

 

[samkent]

Interesting!

But the cable would also be orbiting the Earth at the same speed as the two sats. Which means the path of the cable would be an arc the same shape as the orbital path as the sats.

If the sats thrusted hard enough to keep the cable straight, the weight of the payload would pull on the sats. Increasing the speed of one and decreasing the speed of the other.

Ignoring that effect. Wouldn’t the cable car have to pull itself with the same overall power as would a ordinary rocket, to reach the same orbit?

 

[MeteorWayne]

HI PJay_A, this thread belongs in Space Business and Technology, so I'll move it there. I'll leave a copy here over the weekend.
Meteor Wayne

 

[tampaDreamer]

If the cable goes low enough to catch a hot air balloon, it'll catch a lot of atmospheric drag. Also I think the cable will constantly tend toward the arc of the orbit, with constant thrusting required by the satellites. I don't think this proposal works without perhaps something like vasimr, if proven.

 

[emudude]

I think the drag would be minimal, if he is talking about an altitude of about 50km...but I still agree with tampadreamer, VASIMR technology or something similar would be required to maintain geosynchronous orbit if you consider the payload's effect and the drag, no matter how minimal.

 

[PJay_A]

Interesting!

But the cable would also be orbiting the Earth at the same speed as the two sats. Which means the path of the cable would be an arc the same shape as the orbital path as the sats.

If the sats thrusted hard enough to keep the cable straight, the weight of the payload would pull on the sats. Increasing the speed of one and decreasing the speed of the other.

Ignoring that effect. Wouldn’t the cable car have to pull itself with the same overall power as would a ordinary rocket, to reach the same orbit?

Hmmm... The arcing would be a problem. What if we allow arcing, but reverse the direction of the arc so that the arc pulls downward, with the half-way point using greater mass to pull the arc in the downward direction. If this is done, would the geostationary satellites keep the "bridge" anchored, or would this downward also pull on the satellites, causing them to fall out of orbit? If so, is there a mechanism that that could be incorporated to prevent that?

 

[neilsox]

Yes arc upward, but if the center is depressed toward Earth even slightly, the center is less than orbital speed so the depression will increase until the the center is at an altitude of 50 kilometers. 2 Any lower and the cable will get hot in the atmosphere = considerable energy is needed to prevent dropping lower. The cable needs to be about 91,000 kilometers long = about the length of the Edwards type space elevator. 3 The stress on the cable is about the same as for the Edward's space elevator = the cable material is not yet available 4 The cable has more mass than the satellites = the satellites need to be higher than geosynchronous orbit = about 45,000 kilometers so the center of mass is about 36,000 kilometers = about 40,000 kilometers, I think, as the gravity of Earth decreases somewhat with increasing altitude. Otherwise I think it works as the original post suggests.
Somewhat less demanding on the strength to weight ratio of the cable is the rotating bolo, which also needs to be thousands of kilometers long to have low ground speed at 50 kilometers, altitude. There are details in the forum at http://www.liftport.com If bolo does not find it, try rotating tether. Neil