Space Elevator Climber Design

A space elevator is a long ribbon that extends into space and hangs in a state of equilibrium because the centrifugal force throwing the top half of the ribbon out into space balances the force of gravity trying to drag the bottom half down. The elevator becomes functional when a climber car uses the ribbon to lift itself into space. The ribbon will be a few microns thick and several inches wide and likely made of carbon nanotubes.

The simplest way to climb the ribbon is to use some form of friction rollers that can grip it and then spin to climb up the ribbon. The rollers will require an electric motor to spin them and that means there is a power supply needed. Batteries would add too much weight to the car. Many proposed solutions involve using a laser beam to transfer energy to solar panels mounted on the climber. The source beams can be placed both on the ground and in space.

The voyage of the climber car changes significantly at different stages in the journey. The entire climb involves a distance of just over 36,000 kilometers to reach a geosynchronous altitude and farther if the climber is to be launched into a trajectory designed to reach other positions, such as the asteroid belt. The first 100 kilometers will involve the atmosphere and the possibility of weather phenomena. Once the climber car is beyond the atmosphere, there is no more resistance from air friction and the car can go faster. Limiting the climber to a speed of around 300 km/hour will result in a trip that takes over 5 days. If the climber can go faster as it gets higher and weighs less, the time may decrease.

The climber will need to be a spacecraft, with a contained atmosphere and life support mechanisms to meet the needs of the duration of the journey. It will need to be made from light but strong materials and will need to have extendable solar panels. In fact, since the climber can be slung out from the end of the ribbon toward other destinations in the solar system, by being released at a point that is beyond the geosynchronous middle, it may in fact be a space craft intended to make a journey longer than just the climb out of the gravity well. This uses the same principle as throwing a rock with a sling that is spun around before releasing the rock. The point of release determines the trajectory.

Another factor involved is that if the climbers are to be used to simply reach the geosynchronous level and then return to Earth to pick up more cargo, the climber also must be lowered back down the cable. This takes up valuable time and cargo capacity on the ribbon. It is likely to be cost effective to simply find some other use for the climber cars in space, instead of returning them to the ground. This would make the trips into space one way. If the space elevator is to be used to lift people and materials to space habitats, it makes sense to use the climber cars as part of the construction process in building the habitats. They can be designed to become a part of a space wheel that is fit into a framework when it arrives at the construction site.

If a superconducting thread can be woven into the ribbon, it may become possible to feed the power to the friction rollers through the ribbon itself. This also might allow linear accelerators to be used for the lifting process.

SEE ALSO:
Space Elevator Fundamentals
Space Elevator
Climbing a Cable to Space

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