Spaced

Random thoughts on space elevators:

Is it possible to build a perfectly balanced highway to space? A space elevator? The news is full of reports on progress on this rather exotic concept.

It seems to me that even if the space elevator were perfectly balanced (whatever this means), if an accident broke the elevator in the middle, the top half would be released and eventually would drift away not because of atmospheric drag, but because of irregularities in the orbit of the asteroid or other weight used as an orbiting anchor. Not to mention the orbital velocity of the orbiting elements.

On the other hand, it might break apart. I haven't decided what would happen to the bottom half, although intuitively, it would seem likely to sheer apart. The reason is that while parts of the lower half might be going at orbital speeds, other parts would not.

Think of it this way: The Shuttle, at about 300 miles above the Earth, moves at about 17,000 miles per hour (MPH) relative to the Earth. Since the maximum speed^1 of Earth's rotation is about 1,000 miles per hour relative to a theoretical, non-rotating Earth (or, alternatively, to the celestial sphere projected inversely upon the Earth), the difference would have to have an effect on those elements of the space elevator whose orbital speed is not at the appropriate speed. Consider, further, that the lower one orbits, the faster the speed that one must travel relative to the Earth maintain that orbit. For this reason, escape velocity is about 25,000 miles per hour close to the surface of the Earth.

After writing the above, I found a great site simulating accidents involving space elevators.

Space elevators -- a far-out idea? Or one whose time has come?

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1. The speed of the Earth's rotation varies depending on where on is on the surface. Rotational speed is at or very near its maximum at the Earth's equator, which is why rockets are launched there (e.g., Cape Canaveral for NASA and French Guiana for ESA). The linear speed of Earth's rotation at the exact poles is exactly zero.

[Editing for typographical corrections or enhancements, or for purposes of clarification, not specifically noted.]