On Friday, June 12, 2020 at 7:08:10 AM UTC-4, Niklas Holsti wrote:
On 2020-06-11 21:16, Scott Kozel wrote:
On Thursday, June 11, 2020 at 1:24:46 PM UTC-4, David Spain wrote:

Another feature not to be discounted are stops along the cable that
remain in the atmosphere. You could have observation stations in both
lower and upper troposphere, stratosphere and ionosphere. Something that
is exceedingly difficult to do today, even with balloons.

Something that I haven't heard addressed, is how to protect the cable from
aircraft collisions. No matter how well marked and lighted, sooner or later an
aircraft will hit it, resulting in the severing of the cable and the crashing of
the aircraft.

Perhaps the fixed part of the cable (the orbital tower) should end high
up, higher than planes fly and significant storms blow. The small hop
from and to the ground could be handled by winched cables, no big
problem if one of them gets hit, although the load/cab being winched up
or down may be lost, of course.

The only important reason for anchoring the cable to the Earth's surface
arises if the cable is used to accelerate significant amounts of _net_
mass (upwards mass flow downwards mass flow) to orbital or escape
velocity, in which case the cable has to bend to the west (along the
rising direction) and extract momentum from the Earth's rotation through
its connection to the surface. This connection could of course also be
designed to tolerate isolated airplane strikes, for example it could
consist of many thinner cables that connect to widely separated points
on the ground but converge to the central, main cable high up. The
failure of one or two of the thin cables could be tolerated, and the
cables could be replaced.

Another comment: accelerating a cab outwards along the cable by
"centrifugal" force at altitudes above the geosynchronous is not really
a "free ride", because the momentum has to come from somewhe either
from rocket propulsion, or from the cable's orbital momentum (which is
not suistainable), or from the Earth's rotation, via tension in an
inclined cable.

Something that I read in the literature a few years ago, what happens if the
cable breaks?

It would depend on where it breaks, as to what part falls to the ground,
what part heads out into space, and what part might just wave around at high
altitude and not fall.

Also the expense of rebuilding part or all of the elevator cable.