2000 — Space Elevators: An Advanced Earth-Space Infrastructure for the New Millennium
August 2000
Author: David Smitherman, NASA Marshall Space Flight Center.
Cover Artwork: NASA artwork of the space elevator was created by Pat Rawlings, Science Applications International Corporation. This illustration for a space elevator concept is taken from the geostationary transfer station looking down the length of the elevator structure toward Earth. Electromagnetic vehicles travel the length of the elevator to transfer passengers and cargo between Earth and space. Six vehicular tracks surround a high-strength tubular core structure fabricated from advanced carbon nanotube materials. Three tracks carry passengers and cargo vehicles, while the other three tracks provide for service vehicles that maintain the elevator systems. Large reels with high-strength cables work back and forth to provide small adjustments to the position of the geostation and an asteroid counterweight above (not shown) to maintain the center of mass for the entire structure at a geostationary point above the Earth. Inflatable spheres and space station modules provide habitable volumes for the transfer of passengers and cargo through the station to outbound orbital transfer vehicles.
SUMMARY
This conference publication, “Space Elevators: An Advanced Earth-Space Infrastructure for the New Millennium,” is based on findings from the Advanced Space Infrastructure Workshop on Geostationary Orbiting Tether “Space Elevator” Concepts, held in June 1999 at the NASA Marshall Space Flight Center, Huntsville, Alabama. Subsequent consultation and review of the document with the participants was made prior to publication to clarify technical data and ensure overall consensus on the content of this publication.
Introduction: What is a Space Elevator?
A space elevator is a physical connection from the surface of the Earth to a geostationary Earth orbit (GEO) above the Earth ≈35,786 km in altitude. Its center of mass is at the geostationary point such that it has a 24-hr orbit and stays over the same point above the equator as the Earth rotates on its axis. The vision is that a space elevator would be utilized as a transportation and utility system for moving people, payloads, power, and gases between the surface of the Earth and space. It makes the physical connection from Earth to space in the same way a bridge connects two cities across a body of water (see cover art and fig. 2).
The Earth to GEO space elevator is not feasible today, but could be an important concept for the future development of space in the latter part of the 21st century. It has the potential to provide mass transportation to space in the same way highways, railroads, power lines, and pipelines provide mass transportation across the Earth’s surface. The low energy requirements for moving payloads up and down the elevator could make it possible to achieve cost to orbit <$10/kg. The potential for low-cost mass transportation to space makes consideration of the technology paths required for space elevator construction very important today. The technology paths are beneficial to many other developments and can yield incremental benefits as progress is made toward making space elevator construction feasible.
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