N
nexium
Guest
The space elevator described at www.liftport.com seems to be much the same as the Dr. Edwards elevator. The CNT = carbon nano tubes needs to be hundreds of times stronger than Kevlar for the starter ribbon to have a mass of 20 tons and the finished ribbon 200 tons. The climbers = lifters or elevator car will be only 5% to 10% of the total ribbon mass, so the total movement is rather small. Perhaps more important, nothing happens a few miles up the ribbon when a climber starts up the ribbon. The ribbon stretches locally due to the weight which is increased by the climber accellerating up the ribbon. The stretch transient travels up the ribbon at perhaps 500 kilometers per hour, so the climber could outrun it's own stretch transcent.<br />If my 500 kilometer per hour estimate is average, it is 200 hours before the far end starts to fall toward Earth. By then the climber is likely past GEO altitude, and is now pushing the ribbon away from Earth which partially cancels the pulling it was doing the first 36,000 kilometers. If the climbers stop at or before GEO altitude or leave the ribbon for destinations elsewhere in the solar system instead of parking at the far end as a counter-weight, there are acumulating problems keeping the ribbon from falling toward Earth. Over periods of weeks, it will require careful management of the transcients traveling on the ribbon. Over compensating can mean the ribbon is tryng too hard to move away from Earth which may break the ribbon due to excessive tension. This is an unlikely problem, unless telemetering gives bad data and/or humans make a bad judgement call or micro meteorites damages the ribbon just before a strong transcient arrives. Please embelish, refute and/or comment as I may have this wrong. Neil