Micro Gravity and A Space Elevator?

So while I'm still on the subject, seems likely if you have gone to all
the trouble and expense to build a space elevator you'd design it so
that the masses are attached to the cable in such a way that
here are both anchor cable and transport cable. So the 'elevator' can
pass by the 'station platforms' on the way up. At the counter-weight
mass you might also have the cable to extend beyond with a slightly
smaller counter-weight to give you negative g. Perhaps on a separate
elevator with an 'upside-down' orientation!

So the 'elevator' would be designed more like a vertical train. In fact
it is probably wise to have multiple transport cable 'tracks'. Then you
can simultaneously have trains going up and down. There could be
separate cars on the train that could be unloaded at various
drop-off/platform stops along the cable. Thus you could have stops at
300miles, 500miles, 1000miles (oops! Van Allen Belt!!) etc. up to and
beyond geosynchronous orbit. The 'train' would need to travel fairly
fast if you want to get to anywhere above the Earth's atmosphere in any
'reasonable' amount of time. But the 'elevator' could travel at
different speeds at different points along its journey. With less air
resistance the higher up it is the faster it can go. I'm thinking
something along rail gun technology. Of course if you're willing to wait
months to get to your destination, you can go more slowly. So the cabs
have to be more like living habitats that move (imperceptibly).

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.

Dave

On 2020-06-11 1:24 PM, David Spain wrote:
But the 'elevator' could travel at
different speeds at different points along its journey. With less air
resistance the higher up it is the faster it can go. I'm thinking
something along rail gun technology. Of course if you're willing to wait
months to get to your destination, you can go more slowly. So the cabs
have to be more like living habitats that move (imperceptibly).

Actually, have read articles that suggest rocket propulsion for this
purpose. To save on carry along oxidizer, maybe another use for a
SABRE[1] engine? Like the old water powered steam engines or even modern
locomotives, you'd make way stops to refuel. Thus there may also be
required a 'cargo' train/elevator or cargo cars. I'm going to coin a new
noun for these things. The Space Trelevator or just Trelevator for
short. All Aboard! :-)

Fun to imagine how such tech would be managed/implemented.

Dave

[1] https://en.wikipedia.org/wiki/SABRE_(rocket_engine)

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.

On 2020-06-11 2:16 PM, 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.


As well as bad weather, high shearing winds, lightning strikes etc.
which would be all too common a problem no matter how well you sited the
ground station.

As far as stray aircraft is concerned: Well one of the schemes to power
the cable climber, uses ground based lasers to power it.

Just sayin'.... :-)

Dave

PS: On a serious note, doesn't look to me where the proposed ground site
would be, right along the equator and possibly out at sea to the west of
South America, near the Galapagos Islands, is a highly traversed area of
air transit. Obviously this would need to be an air travel exclusion
zone. But there is also terrorism to consider...

On Thursday, June 11, 2020 at 2:37:27 PM UTC-4, David Spain wrote:
On 2020-06-11 2:16 PM, 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.


As well as bad weather, high shearing winds, lightning strikes etc.
which would be all too common a problem no matter how well you sited the
ground station.

As far as stray aircraft is concerned: Well one of the schemes to power
the cable climber, uses ground based lasers to power it.

Just sayin'.... :-)

Dave

PS: On a serious note, doesn't look to me where the proposed ground site
would be, right along the equator and possibly out at sea to the west of
South America, near the Galapagos Islands, is a highly traversed area of
air transit. Obviously this would need to be an air travel exclusion
zone. But there is also terrorism to consider...

Hurricanes, tornadoes, etc.

Plus someone else mentioned satellites

In article ,
says...

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.

Post 9/11 I agree that this is something to seriously consider.

Micrometeorite and orbital debris is also a huge concern. It's not like
a space elevator can initiate a collision avoidance maneuver. Better
add clearing out all significant orbital debris to the price tag of your
space elevator.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

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.

--
Niklas Holsti

niklas holsti tidorum fi
. @ .

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.

"Scott Kozel" wrote in message
...

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.

I saw someone do the math once. Ignoring any payloads, the cable itself is
so light that it "falling" on pretty much anyone or anything most likely
wouldn't do much kinetic damage. As for other problems (say falls against a
road, truck runs into it) that's another issue.

It certainly would be fairly spectacular to see though!

BTW, still worth reading "Fountains of Paradise" by AC Clarker.


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
https://www.amazon.com/Disaster-Resp...dp/1484221834/

On Jun/12/2020 at 13:27, Greg (Strider) Moore wrote :
"Scott Kozel"Â* wrote in message

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.

I saw someone do the math once. Ignoring any payloads, the cable itself
is so light that it "falling" on pretty much anyone or anything most
likely wouldn't do much kinetic damage. As for other problems (say falls
against a road, truck runs into it) that's another issue.

What happens is a complex issue. I wouldn't trust it to gently lay
itself on the ground. If the cable breaks, I would get out of its path.

Imagine if the cable breaks near the top. The broken off part just flies
off, we can ignore that part. The top of the cable still anchored to the
ground is still pulling the bottom part up but the bottom part is
pulling down harder than the top part, so the cable is slowly coming
down vertically. At first the cable is still taut, but it is gaining
vertical speed downward. This puts some slack in the top of the cable,
not the bottom where the pull is stronger. The bottom part of the cable
is accumulating on the ground near the anchor point. After a while, the
top part has too much angular speed for its lower altitude and starts to
pull the cable eastward. As the cable gets lower, this eastward pull
becomes stronger and the cable that was on the ground near the anchor
point starts being pulled eastward. When all the slack of the grounded
cable is taken up, the cable now has significant eastward speed and you
have a huge mass with significant speed pulling eastward. SNAP. Not pretty.

Now imagine that instead of breaking near the top, the cable breaks near
geosynchronous altitude. Much the same as above happens again, even if
the top part at geosynchronous altitude is not pulling up, it wants to
stay at its altitude but is pulled down by the bottom part. Things go
along much as in the case where the initial break was much higher up, it
only happens in a different time frame.

Imagine this time that the cable breaks at an altitude of 10,000. This
time ignore the bottom part which hits the ground. A little more
surprisingly, the top part will do much as the two examples above. The
cable first goes up vertically, then the bottom part loses angular
momentum. It starts pulling the cable westwardly, this westwardly pull
accelerates, but mostly in the bottom, while the top is accumulating
some slack. After a while, the top part receives the cue that there is a
big westwardly pull. Again SNAP.

In reality, all of the above can happen together. Different parts of the
cable will be pulling in different directions there will be some slack
accumulating here and there and the the cable becoming taut again and
snapping here and there.

The pieces falling to the ground might not be taut. Who knows, you could
have some big balls of cable that have curled up. And even if you don't
have big balls of cable, you can have some cable fall lightly to the
ground and then be dragged eastward pulling anything with it.

The physical properties of the material used to make the cable would
also have an effect on what happens.

Just a simple cable breaking could have a mostly unpredictable chaotic
outcome. One could put in some apparatus here and there on the cable to
keep it somewhat under control. If you roll in the cable where some
slack accumulates, you don't end up having wide speed differences for
different parts of the cable.

It certainly would be fairly spectacular to see though!

Yes. :-(


Alain Fournier