Originally posted by twhitehead
If you follow the link you will find that yes, they not only thought about it, but factored replacement of the whole cable every few years into the equation.
[b]There would also be the issue of how to stop terrorists from flying aircraft or missiles into the cable.
Would this be harder or easier than say flying a plane into the shuttle launch faci easily takes care of most of your protection issues - except possibly a large aircraft impact.[/b]
Would this be harder or easier than say flying a plane into the shuttle launch facilities?
No, but it may do more costly damage that would be much harder to repair and take longer to repair. Replacing and repositioning such a cable way up in outer space would surely be extremely costly compared with repairing a mess on the surface of the Earth where we have much easier access!
“....the fixed costs would be US$6 to 12 billion, for construction; and one-way designs (such as Edwards'
will add to the cost of the elevators ...”
( this is probably an optimistic estimate since most major engineering projects of this sort tend to go over budget )
“...Building Space Shuttle Endeavour cost about US$1.7 billion. One Space Shuttle launch costs around $450 million ...”
so, on the bases of the above figures, I would imagine that it would cost much less to repair the damage done by an aircraft flying into a shuttle launch facility than into a space elevator cable by perhaps, very roughly, one order of magnitude. If you have figures for estimated costs that falsify this then I would like to see them.
Also, the taller something is, the more attractive as a target it may appear to be to a deranged terrorist mind; and you cannot get much taller than this!
Once this gets built, it would become a massive symbol and be the priority target in the minds of many terrorists.
OK, having said all that, I concede that the risk of terrorist attack can be made insignificant simply by keeping a permanent military presence around the cable so terrorism shouldn't be the main consideration. But the question of a possible terrorist attack would be a very trivial side point compared to what I clearly have said would be the main risk which would clearly not be a terrorist attack but would be, as I said “... the occasional piece of space-rock or space junk colliding with the cable in space thus cutting it -what the hell would they do about that? - I think this would be the main safety problem.
Even the inevitable collisions with tiny bits of space dust would gradually damage the cable -have they even thought about that? ...”(my previous comment)
With such a massive length of cable in space all the way up just past geostationary orbit would mean it surely wouldn't be particularly unlikely for something to collide with it. Would you disagree?
Simply having multiple cables in a weave of some sort easily takes care of most of your protection issues
wouldn't having multiple cables rather than one massively increase costs? Having to do that would make the alternatives look even more attractive from purely the cost point of view.
Personally I think one ( not sure which one ) of the laser propulsion alternatives would be the most attractive option:
The technology needs a lot of costly development before it becomes practical but, once developed, it would offer significant advantages over both using rocket power ( which is very energy inefficient because, unlike with laser propulsion, most of the energy is used just lifting the fuel ) and using a space elevator ( which requires a massive space cable and a massive space counterweight ) .