How a space elevator would work

A space elevator is a proposed transportation system connecting the Earth’s surface to space. The elevator would allow vehicles to travel to orbit or space without the use of rockets. While elevator travel wouldn’t be faster than rocket travel, it would be much less expensive and could be used continuously to transport cargo and possibly passengers.

Konstantin Tsiolkovsky first described a space elevator in 1895. Tsiolkovksy proposed building a tower from the surface up to geostationary orbit, essentially making an incredibly tall building. The problem with his idea was that the structure would be crushed by all the weight above it. Modern concepts of space elevators are based on a different principle — tension. The elevator would be built using a cable attached at one end to the Earth’s surface and to a massive counterweight at the other end, above geostationary orbit (35,786 km). Gravity would pull downward on the cable, while centrifugal force from the orbiting counterweight would pull upward. The opposing forces would reduce the stress on the elevator, compared with building a tower to space.

While a normal elevator uses moving cables to pull a platform up and down, the space elevator would rely on devices called crawlers, climbers, or lifters that travel along a stationary cable or ribbon. In other words, the elevator would move on the cable. Multiple climbers would need to be traveling in both directions to offset vibrations from the Coriolis force acting on their motion.

The setup for the elevator would be something like this: A massive station, captured asteroid, or group of climbers would be positioned higher than geostationary orbit. Because the tension on the cable would be at its maximum at the orbital position, the cable would be thickest there, tapering toward the Earth’s surface. Most likely, the cable would either be deployed from space or constructed in multiple sections, moving down to Earth. Climbers would move up and down the cable on rollers, held in place by friction. Power could be supplied by existing technology, such as wireless energy transfer, solar power, and/or stored nuclear energy. The connection point at the surface could be a mobile platform in the ocean, offering security for the elevator and flexibility for avoiding obstacles.

Travel on a space elevator would not be fast! The travel time from one end to the other would be several days to a month. To put the distance in perspective, if the climber moved at 300 km/hr (190 mph), it would take five days to reach geosynchronous orbit. Because climbers have to work in concert with others on the cable to make it stable, it’s likely progress would be much slower.

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