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From: Stan Berkovich, of Evanston IL
To: Bill Reeves, flight director for the planning team

Question: (Perhaps this is the wrong forum to ask this question, but...) Are there any plans to test/develop an earth-to-orbit tether any time in the near future? I've heard that the materials that can make this sort of experiment possible are finally available in large quantities. Maybe the elusive orbital tower is many years away, but why not start with a very thin tether dropped from low orbit into the upper atmosphere, say 10 miles below? Would it not be possible, then, to start at geosynchronous orbit, and drop a much longer tether (after a series of progressively longer test-drops) in both directions, resulting in a 40,000 mile-long moderately-loose thread, along which small test payloads could climb? Moreover, wouldn't it also be possible to assist in positioning the atmospheric section of such a tether with high-altitude aircraft flying within limited circular patterns? Are there no experiments in this area currently planned? -Stan Berkovich

Answer: Stan,

Actually, a tethered satellite experiment has twice flown aboard the Space Shuttle, the last aboard STS-75. This experiment involved an "upward" deployment of a small satellite attached to the Shuttle with a 20 km long electrically conductive tether. The plan was to demonstrate the power generation capabilities of long, conductive space tethers as they moved through the earth's magnetic field at orbital velocity. Unfortunately, during the deployment of the tethered satellite on STS-75, the tether broke just before reaching its fully deployed length, but not before many of the electrodynamic properties of this system were demonstrated.

Although there are no additional tether demonstration flights currently on the Shuttle manifest, it is quite possible that this promising technology will one day fly again aboard the Shuttle. "Downward" deployments of satellites into the earth's upper atmosphere have been considered for future missions.

Tethered spacecraft have been successfuly tested on unmanned vehicles and additional missions are planned.

For information about the difficulties of constructing the "space elevator" that you alluded to, check out the following URL:

http://liftoff.msfc.nasa.gov/academy/tether/SpaceTowers.html

Thanks for your question, Stan.

Paul Snow
Rendezvous Guidance & Procedures Officer



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Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 10/15/2003
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