Hello all, I'm new to the forum.

I've spent many years thinking about a star ladder and I happen to think that in years to come, it will supercede rockets as the way people and mass is taken up into the skies above. It's great that I can express my views on a forum for other people to read who are also interested in seeing this project come to life.

I subscribe to the view that the star ladder will initially be laid out with a tiny, seed thread and will be reeled in by the counterweight and slowly reel in a thicker and stronger ribbon.

I say, that why not cash in on the potential a star-ladder has for powering the earth? Consider for a second a giant array of solar panels in orbit, harvesting electrical energy. Thousands of joules of solar energy are reflected back into space by the Earth's atmosphere.
In years to come, we are still going to have an energy crisis, nuclear, coal, oil and gas will be dwindling as we fight for control of what little fossel fuels remain on this planet. Meanwhile, the sun will still be shining for billions of years.

If during the construction of the ribbon, you could reel up a power line made out of a special nano-tech material designed for electrical conductivity whilst still being lightweight and super-strong, you could do three things:

1. Provide people on Earth with free electrical energy.
2. Power the climber via Electromagnetic induction from the power line inside the ribbon.
3. Gain funding from environmental groups to help begin the construction of the star ladder.

Why should the star ladder be purely about bringing people and mass to and from space? Why not energy as well....

Those are my thought, I would really appreciate any feedback anyone has to say about the matter.

Thanks those for taking the time to read my post.

Kind Regards,

Alistair Smith

As an alternative to winching electrifying the first say 300 km of the ribbon is probably worth while.  This would power the lifter through the atmosphere.  After that the solar panels can be opened in a vacuum.  The ribbon would need splitting into two and coating with an insulator.  The coating may also protect the ribbon against oxygen.

Electrifying the cable up to 1000 km would reduce the mass of photovoltaic cells by a quarter.  The same quantity of cooling is still needed.

Where:
P = Power in Watts
I = Current in Amps
V = Potential difference in Volts
R = Resistance in Ohms

P = I V

P = I² R

P = V² / R


Although trains are normally powered by 600 V dc (direct current) and power transmission lines work as 110 kV ac (alternating current) the resistances are so high that I am using the extra high voltage of 1200 kV ac.
http://en.wikipedia.org/wiki/Electric_power_transmission
http://en.wikipedia.org/wiki/High_Voltage

At a height of 200 km the resistance is 40 mega-ohms

P = V² / R = 1.2 e 6 ^2 / 4 e 7 = 36,000 Watts = 36 kW

At s height of 1000 km the resistance is 200 mega-ohms.

P = 1.2 e 6 ^ 2 / 2 e 8 = 7,200 Watts = 7.2 kW

Unfortunately the climbers need mega-Watts.  To be usable voltages 100 times larger or resistances 100 times smaller or a mixture.  Depending on how the cables are made the resistance used in these calculations may be too high.

There is a plan to use ribbon that is 1 cm in width below 10 km, taking that up to 200 km.

1 cm diamter = 0.01 m = 0.005 m radius
A = pi r² = pi * 0.005 * 0.005 = 7.85 e-5 m^2

If split in two, for power up and power down, the cross section are becomes 7.85 e-5/2 = 3.93 e-5 m^2


ρ = R A / l  can be re-arranged to   R = ρ l / A

ρ for CNT =  10-4 Wm (or 1 e-4)


For a height of 200 km = 200,000 m

R300 = 1 e-4 * (2 * 200,000) / 3.93 e-5 = 10,200,000 =  10.2 mega-ohms

I recall a single wire transmission line for radio frequencies. IIRC = If I recall correctly the efficiency was good for a few meters. Any chance efficiency is good for thousands of kilometers? A capacitor can not be avoided at the far end, but the Q is very poor as the other side of the capacitor has to find its way though space and Earth's atmosphere. Have you more details?   Neil

I do not think the ribbon will be able to be used for trasmitting power back to earth untill a room temperture super conductor that has much the same characteristic of carbon nanotubes is developed.

For powering the climber at the start of its run seems like it would be quite easy. I think running it out to 1000 km might be difficult but 100 km or so might be possible. This would get it above almost all of the atmosphere. A conducting strip on either edge of the ribbon would provide a sort of third rail and a complete circuit while the climber is on the ribbon.

http://www.physorg.com/preview100445957.html

Seems to me such wireless transfer of energy would in large part alleviate both the weight of the "transmission lines" and associated problems with resistance.  Further, no physical connection is then required between the ribbon and lifter, so friction and drag should be greatly reduced, if not eliminated from such a connection.

While not a scientist or engineer as many of you appear to be, from a logic stance, it would seem that using a magnetic propulsion system to power the lifter would be one of the "best options".  We already have the technology and experience building such systems.  Such a system would not have to use "rollers or other mechanical attachement to the ribbon", which would mean less friction, wear and tear, and chance to damage the ribbon from such a mechanical form of locomotion. 

As A.M. Swallow already posted in the precurser section:

http://www.newscientisttech.com/channel/tech/mg19125686.300-rusty-rind-adds-magnetic-allure-to-nanotubes.html

It appears both feasible and likely that by the time the nanotube ribbon material is likely to be available in such quantities and length to start building the ribbon, that making such nanotubes magnetic should be also well developed. 

Taken together, the wireless transfer of energy, and magnetic propulsion would give us an extremely efficient and lightweight alternative to both power and give locomotion to the climbers. This system would also resolve some of the questions about how to place/power navigational beacons on the ribbon, the concern of atmospheric drag on lifter based solar panels, and provide a simple method for providing power to the life support needs of the lifter without added weight of batteries, engines or other options that have been discussed.

As an added bonus, the high efficiency and low friction of the magnetic propulsion system can create a very high rate of speed and accelleration over distance, that might well be able to shorten the currently accepted, 7 day trip estimate. 

This approach also adds another future capability to the space elevator.  While a standard lifter would be accellerated and then decellerated by the magnetic propulsion system to allow for a safe and easy docking at the top of the elevator, this same "ribbon" and propulsion system could continue to accellerate specially designed "lifters" that would instead use the speed and inertia gained from the lifting system to "launch" from the ribbon as self contained space ships.  Such a system would likely be the cheapest and most efficeient model for supplying/cargo hauling to both the moon and mars.

I think the balloon assist is a very clever idea. I do not know how easy it would be to put into practice but it would allow for a number of possibilities. More climber could be on the ribbon at any one time since the load at the location of the highest gavity would be reduced. It would be a way to increase the maximum load the elevator could carry for the same reason. It could provide an additional safety feature for the elevator durring the period that a failure to the climber or the ribbon could be most dangerous to the cargo.