The orbital elevator is a short variant of skyhook. A sounding rocket carries cargo to the bottom end of an elevator orbiting the Earth at 6 km/s. The cargo gains only 1 km/s when it travels up the elevator. A plastic elevator has the lifetime of a few months and the minimum mass of 100 tons.


Robert Zubrin, "The Hypersonic Skyhook," Analog Science Fiction/Science Fact, Vol. 113, No. 11, September 1993, pp. 60-70.

Eagle Sarmont, "How an Earth Orbiting Tether Makes Possible an Affordable Earth-Moon Space Transportation System," SAE Technical Paper 942120, given at Aerotech '94, Los Angeles, CA, October 3-6 1994.

Robert Zubrin, "The Hypersonic Skyhook," Journal of the British Interplanetary Society, Vol. 48, No. 3, March 1995, pp. 123-128.


The elevator is extremely massive, unless it is made of a material having great specific strength. Buckytubes are too expensive, so the only practical material is a strong plastic. To avoid the extreme radiation of the Van Allen belts, the plastic elevator is restricted to altitudes ranging from 5,000 km to 13,000 km.

The Coriolis force of moving cargo compromises the stability of the elevator. An electrodynamic tether alone cannot restore its orbital momentum, because it would operate at the bottom end of the elevator and would further destabilize it. The electrodynamic tether has to be aided by an ion engine or a solar sail placed at the top end of the elevator.

Orbital elevator

Curator: Al Globus
NASA Responsible Official: Dr. Ruth Globus
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