|NASA Plans Elevators to Space|
Open your imagination now. You hop into the elevator and hit the button for the 11,457,600th floor. Hope you dressed warmly, because when you hop out, you'll be hopping right into space. Science fiction? Not anymore, says NASA.
Amid soaring costs of space shuttle flights, new security concerns, and repeated launch delays, NASA scientists continue to look for slower, yet simpler and reusable ways of getting satellites and into space. One of those ways may just be the space elevator.
According to NASA, a space elevator would essentially be a long cable with one end attached to a point on the Earth's equator while the other end remains held by its own outward centripetal force some some 22,187 miles (35,787-kilometers) directly overhead in a geostationary orbit. Magnetically powered vehicles would climb the cable, serving as a mass transportation system for moving people, satellites and other payloads between the Earth and space.
The space elevator is really a spin-off of an earlier NASA plan for lifting objects into orbit without rockets called Space Towers.
To build a space elevator, NASA would first use the space shuttle to carry reels holding a thin inner-layer of cable into orbit. The cable would then be unrolled with the free end being snaked down from orbit and attached to an anchoring station located somewhere on the Earth's equator. To stabilize the upper-end of the cable, an artificial "asteroid" would be attached to act as a counterweight. With the initial inner cable in place, automated "climbers" would then begin adding additional strengthening layers of cable from the ground up. Total construction time is estimated by NASA at three to five years.
For a cable strong enough to withstand the enormous forces involved, NASA pins its hopes on a newly developed "carbon nanotube" material shown in tests to be over 100 times stronger than steel.
The billions of dollars needed to build the first space elevator would more than be recovered through both its commercial potential and downright costs savings, say NASA planners.
The current cost of placing a 26,450-pound (12,000-kg) payload into orbit with the space shuttle is about $264 million. The same payload could be placed into orbit using the space elevator for under $18,000. A human passenger and luggage totaling 330-pounds (150-kg) could ride the elevator to space for under $250.
By utilizing space elevators, developers of delicate communications satellites will no longer be forced to sacrifice innovation to the necessity of building their satellites to withstand the forces of being blasted into orbit. Larger, far more capable satellites could be placed into orbit at much lower costs and almost zero risk of damage.
The idea of space elevators is not at all new. As early as 1895, Russian Scientist Konstantin Tsiolkovsky, inspired by the Eiffel Tower, wrote of an Earth-orbiting "celestial castle" tethered by a cable. In his 1978 novel, "Fountains of Paradise," famed science fiction writer Sir Arthur C. Clarke envisioned a space elevator built of the very carbon fiber materials being studied today.
The timetable for construction of an actual space elevator hinges mainly on development of the carbon-based building materials. While NASA is using a planning horizon of the year 2100, private-sector companies currently working on designs think an operating space elevator could be built by as early as the end of this decade.
Geostationary Orbit: An object in a geostationary orbit remains directly above a fixed point on the Earth's equator at an altitude of approximately 22,187 miles (35,787 km) above mean sea level. A satellite in a geostationary orbit is in fact orbiting the earth at the same rate at which the earth is rotating. Most communications satellites are launched to remain in geostationary orbits.
Centripetal Force: When you are riding in a car on a curve, centripetal force is what makes your body move in the opposite direction, away from the radius point of the curve. [Illustration]