Space Elevator

On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
:By CARL HARTMAN, Associated Press Writer
:
:WASHINGTON - President Bush (news - web sites) wants to return to the
:moon and put a man on Mars. But scientist Bradley C. Edwards has an
:idea that's really out of this world: an elevator that climbs 62,000
:miles into space.

OK, so you use a whole lotta solar power beamed at your cart to climb
62,000 miles straight up (without becoming a crispy critter, but
that's another topic).

Where are you going to get the mass and energy to accelerate yourself
laterally to reach orbital velocity? Aren't you just going to
decelerate the beanstalk and send it whipping to the west as the earth
rotates beneath you, winding the beanstalk along the equator like an
earth sized yo-yo?


At 24,000 mile you're at geosynchronis orbit, ready to float free. If
you want an orbit lower down you just burn a little rocket fuel (that
you brought up with you) to slow down & drop lower.

The other 38000 miles of line wants to pull away from the Earth so
acts as a counter weight keeping the whole thing pulling straight up.
If you keep going past the 24,000 mark before cutting loose you start
picking up the velocity you need to get to the Moon, as well as many
other fun spots around the system .

Any deflection caused by sending payloads up gets cancelled out by
stuff coming back down, i.e "My Parents Went to Jupiter & All They Got
Me Was This Cheap T-Shirt" x 10-6.

H.

"Howard Eisenhauer" wrote in message
news
On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
:By CARL HARTMAN, Associated Press Writer
:
:WASHINGTON - President Bush (news - web sites) wants to return to the
:moon and put a man on Mars. But scientist Bradley C. Edwards has an
:idea that's really out of this world: an elevator that climbs 62,000
:miles into space.

OK, so you use a whole lotta solar power beamed at your cart to climb
62,000 miles straight up (without becoming a crispy critter, but
that's another topic).

Where are you going to get the mass and energy to accelerate yourself
laterally to reach orbital velocity? Aren't you just going to
decelerate the beanstalk and send it whipping to the west as the earth
rotates beneath you, winding the beanstalk along the equator like an
earth sized yo-yo?


At 24,000 mile you're at geosynchronis orbit, ready to float free. If
you want an orbit lower down you just burn a little rocket fuel (that
you brought up with you) to slow down & drop lower.

The other 38000 miles of line wants to pull away from the Earth so
acts as a counter weight keeping the whole thing pulling straight up.
If you keep going past the 24,000 mark before cutting loose you start
picking up the velocity you need to get to the Moon, as well as many
other fun spots around the system .

Any deflection caused by sending payloads up gets cancelled out by
stuff coming back down, i.e "My Parents Went to Jupiter & All They Got
Me Was This Cheap T-Shirt" x 10-6.

H.

This space elevator thing is elegant in a Newtonian sort of way but I
suspect that there is a lot more to it that hasn't been completely thought
out.

They say put it on the equator where the winds are low. Well, they are low
most of the time but there is always the occasional typhoon.

Then there are the electrical effects. A carbon nanotube cable will conduct
electricity pretty well. Some claim it's a room temperature superconductor
candidate. A tropical lightning strike can be several million amps and this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts per
meter.

What about tidal effects? Twice each day the Moons gravity will pull on the
structure.

Bill Daniels

On Sat, 26 Jun 2004 23:15:26 GMT, "Bill Daniels"
wrote:


"Howard Eisenhauer" wrote in message
news
On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
*Snip*


H.

This space elevator thing is elegant in a Newtonian sort of way but I
suspect that there is a lot more to it that hasn't been completely thought
out.

You may well be right- not really my field but I've heard the math is
the same as applies to suspension bridges, thats to say well
understood.

They say put it on the equator where the winds are low. Well, they are low
most of the time but there is always the occasional typhoon.

True, but anything with the kind of strength we're talking about here,
under that amount of tension ain't gonna be much bothered by the
occaisional blow.

Then there are the electrical effects. A carbon nanotube cable will conduct
electricity pretty well. Some claim it's a room temperature superconductor
candidate. A tropical lightning strike can be several million amps and this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts per
meter.

Last I checked deltaV/m was more liket ~200V. I heard the speculation
about nanotubes being superconductors a few years ago back before they
were able to produce them in decent quantities but haven't heard
anything since, If they really are I think somebody would have noticed
by now. To bad though, a superconducting space elevator would be a
neat way to generate "free" power, a-la the NASA/Italian experiment
with a tether a few years back. .

What about tidal effects? Twice each day the Moons gravity will pull on the
structure.

Bill Daniels

Yes, it will. Geosync satellites get pulled around quite a bit by the
moon (& sun's) gravity. Then they get pulled back again., Not a
biggie.


H.

Arthur C Clarke said that the space elevator would be built "about 20 years
after everyone stops laughing." I think we
have a while to wait yet (heh heh).


My concerns are also practical. The things I have read sound like a bunch of
folks who have the theory analyzed, but
don't really want to confront the real world details. The math has been
worked out in great detail by a cadre of folks
who have been working on this for many years. Just because something is
impossible doesn't stop folks from designing it.
http://www.space.com/businesstechnol..._020327-1.html


anything with the kind of strength we're talking about here,
under that amount of tension ain't gonna be much bothered by the
occaisional blow.


The tensions are unimaginably high at the hub, but at ground level (at the
ends of the tether), they are zero. A typhoon
would be a BIG problem.


Then there are the electrical effects. A carbon nanotube cable will
conduct
electricity pretty well. Some claim it's a room temperature
superconductor
candidate. A tropical lightning strike can be several million amps and
this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts
per
meter.

Last I checked deltaV/m was more liket ~200V.

A dV/dM of 200V per meter, in anything approaching a superconductor could
give nearly infinate
current (I=V/R as R approachs 0 --- Ohms law). That is what burned the
Italian tether. I have not seen
any data on how they plan to avoid this fate. I am sure they have a plan - I
just haven't seen it.

Lightening would do bad things to it I am sure.


I heard the speculation about nanotubes being superconductors a few years
ago back before they
were able to produce them in decent quantities but haven't heard anything
since, If they really are I
think somebody would have noticed by now.

I agree. It probably isn't a superconductor, although there might be a way
to make it into one.


To bad though, a superconducting space elevator would be a
neat way to generate "free" power, a-la the NASA/Italian experiment
with a tether a few years back.

The power is there, using it to power the tram would be downright elegant,
but you sure can't ignore it - ask the Italians.

And the next detail is bullistic damage. It forms a ribbon, very thin but a
meter or so wide (tapering). If a piece of
space debris were to blow a hole in it half way up, sufficiently large to
cause a failure, the consequences
would be amazing, as the upper part went winging off into space, and the
lower part came crashing to
earth with a lot of mass and residual velocities of up to 17,000 mph.



Bottom line - the advances in carbon nanotube manufacture show promise. It
used to be said that this thing needed to be made
from "unobtainium" - now it is not quite so unobtainable (but still not
exactly available either.) but there are still many problems,
and more than one look to me to be showstoppers for now.

In article , Ron Webb wrote:

The tensions are unimaginably high at the hub, but at ground level (at the
ends of the tether), they are zero. A typhoon
would be a BIG problem.

Huh? There'd be no reason to make a system with zero tension at the ground,
and a lot of reasons not to. I'd assume the tension would be quite large for
purposes of stability as well as so the loads going up don't pull the whole thing
down. Certainly one engineering consideration would be making sure the
largest conceivable typhoon would be a non-issue.

From a standpoint of aviation, the biggest concern would be finding enough
red lights so you could put three of them at each hundred foot level, and hiring
enough guys to keep changing them. I make that 9.9 million bulbs.

Of course, they could change the lighting regulations, but if it only takes twenty
years to build the elevator, they might have to put them on anyway....

Mike Beede


Mike Beede

Why don't we just pile the cash up and burn it...wouldn't that be much
cheaper???

What kind of idiots would give them 2.5 million dollars to research this and
NASA gave 1/2 a million.

I wish NASA and congress would take about 10% ofNASA's budget and invest in
researching affordable alternative energy uses that EVERYONE can afford!!!
Solar, etc type of "stuff"......wouldn't you love to be able to fly your RV-6
on the energy of, heck, from the stars??? Solars cells that can pik up energy
from the stars, not to mention our sun. Or affordable batteries for vehicle
that will run your car, aircraft, boat for 800 miles or more at speeds we know
today. I know, I know...this is some BIG pipe dream...but heck, we've gone to
the moon and we perform body transplants EVERYDAY..in fact, I have both
transplanted corneas......if we can do stuff like this..why can't we take some
of what I believe is wasted money and research something that ALL OF US can
utilize and especially afford??? I want to say "SCREW YOU" to OPEC, etc and
just get out in my car and go anywhere I want in something that's not
polluting our skies.

Oh well, just an idea...I can dream, can't I.

Mike Beede wrote:

From a standpoint of aviation, the biggest concern would be finding enough
red lights so you could put three of them at each hundred foot level, and hiring
enough guys to keep changing them. I make that 9.9 million bulbs.

Of course, they could change the lighting regulations, but if it only takes twenty
years to build the elevator, they might have to put them on anyway....

Our guvunmit radar balloons, don't have lights on their tethers...
They geaux up something like 15 to 25k'...

On Sun, 27 Jun 2004 10:22:24 -0800, "Ron Webb"
wrote:

Arthur C Clarke said that the space elevator would be built "about 20 years
after everyone stops laughing." I think we
have a while to wait yet (heh heh).


My concerns are also practical. The things I have read sound like a bunch of
folks who have the theory analyzed, but
don't really want to confront the real world details. The math has been
worked out in great detail by a cadre of folks
who have been working on this for many years. Just because something is
impossible doesn't stop folks from designing it.
http://www.space.com/businesstechnol..._020327-1.html

Agreed, there are plenty of examples out there supporting your case.
On the other hand, it's been proven time & again that Man Will Never
Fly, rendering this whole newsgroupe & many years of postings a bit of
a waste-

Realisticly there is much research & real world experimentation to be
done before the concept is either proven or disproven. Hopefully
they'll offer me a job helping out with that .


anything with the kind of strength we're talking about here,
under that amount of tension ain't gonna be much bothered by the
occaisional blow.


The tensions are unimaginably high at the hub, but at ground level (at the
ends of the tether), they are zero. A typhoon
would be a BIG problem.

I don't think they're un-imaginably big, just a number followed by a
lot of zeros. Everything I've read on the subject says that the
ground anchor would be under tension for stability purposes. However,
consider this- Not being sure of the elastic modulus of a Nanotube &
Glop composite cable, I'll make the un-warranted assumtion it's not
much. So even if the anchor is under little or no tension any big
wind that comes along will have to deal with the inertia of the
cable's portion lying outside of the atmosphere before causing a
deflection. Hurricane winds are limited mostly to the troposphere,
~30,,00 feet at the equater if I recall correctly. I'm pretty sure
there are large suspension bridges around with an equivalent wind load
to 30,000 feet of space elevater that withstand typhoons just fine.


Then there are the electrical effects. A carbon nanotube cable will
conduct
electricity pretty well. Some claim it's a room temperature
superconductor
candidate. A tropical lightning strike can be several million amps and
this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts
per
meter.

Last I checked deltaV/m was more liket ~200V.

A dV/dM of 200V per meter, in anything approaching a superconductor could
give nearly infinate
current (I=V/R as R approachs 0 --- Ohms law). That is what burned the
Italian tether. I have not seen
any data on how they plan to avoid this fate. I am sure they have a plan - I
just haven't seen it.

Lightening would do bad things to it I am sure.


The potential for high voltage is certainly there, but consider that
the source impedance of the atmospere is rather large untill actual
ionization occurs, which would limit the currents available. Possibly
large, but not unlimited. Also, AFAIK, superconducting effect breaks
down once a certain current desity is reached in the conductor,
another limitation. TANFL.

As for lightening, I'm from the school of thought that says a
conductor stuck up into the atmosphere actually discourages
lightening, drains away all those pesky ions in the neighborhood.
leaving a nice insulating volume of poorly conducting air around it.

I heard the speculation about nanotubes being superconductors a few years
ago back before they
were able to produce them in decent quantities but haven't heard anything
since, If they really are I
think somebody would have noticed by now.

I agree. It probably isn't a superconductor, although there might be a way
to make it into one.


To bad though, a superconducting space elevator would be a
neat way to generate "free" power, a-la the NASA/Italian experiment
with a tether a few years back.

The power is there, using it to power the tram would be downright elegant,
but you sure can't ignore it - ask the Italians.

I thought the whole idea of the Italian tether Was to generate power-
wasn't the problem with it a stuck cable reel?

And the next detail is bullistic damage. It forms a ribbon, very thin but a
meter or so wide (tapering). If a piece of
space debris were to blow a hole in it half way up, sufficiently large to
cause a failure, the consequences
would be amazing, as the upper part went winging off into space, and the
lower part came crashing to
earth with a lot of mass and residual velocities of up to 17,000 mph.

Again, I agree with you on the space junk problem, I did hear
recently that the problem has been considered, can't remember what the
take on it was though. But consider this, it wouldn't be just the one
cable, I believe the design would be four or more cables tied
togeather every so often that would tend to minimize the potential
for (hind quarters of a cat mounted on a wooden plaque) from smaller
pieces of junk. The larger pieces' orbits are pretty well defined,
they'd have a good idea of what could cause major damage well ahead of
time. What to do about it? Damned if I know- I guess maybe they're
not gonna give me a job afterall .

I do remember from the same article that the problem of a broken
cable coming down isn't thought to be a major concern. Due to the
density of the cable & it's profile in theory once it hit the
atmosphere, instead of falling down @ 17,000 + change MPH as you (& I
as well) thought, it would end up "fluttering" down, coupla feet per
second range. IIRC the simulation showed it would all end up
reasonably close the the anchor site. Still a big mess to clean up
though-


Bottom line - the advances in carbon nanotube manufacture show promise. It
used to be said that this thing needed to be made
from "unobtainium" - now it is not quite so unobtainable (but still not
exactly available either.) but there are still many problems,
and more than one look to me to be showstoppers for now.


You can never tell what's gonna show up & bitechya on the ass when you
start something as new as this, always unforseen problems there are.
Can't say that I see what they are right at the moment though-

Howard.

According to the newspaper article I read, the proposed fiber is a "tape"
roughly three feet wide and a few thou thick. A flat ribbon is
aerodynamically unstable and will vibrate axially in any wind. This thing
would seem to be the ultimate Tacoma Narrows Bridge. Just my first
impression.

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love
America

"Howard Eisenhauer" wrote in message
news
On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
:By CARL HARTMAN, Associated Press Writer
:
:WASHINGTON - President Bush (news - web sites) wants to return to the
:moon and put a man on Mars. But scientist Bradley C. Edwards has an
:idea that's really out of this world: an elevator that climbs 62,000
:miles into space.

OK, so you use a whole lotta solar power beamed at your cart to climb
62,000 miles straight up (without becoming a crispy critter, but
that's another topic).

Where are you going to get the mass and energy to accelerate yourself
laterally to reach orbital velocity? Aren't you just going to
decelerate the beanstalk and send it whipping to the west as the earth
rotates beneath you, winding the beanstalk along the equator like an
earth sized yo-yo?


At 24,000 mile you're at geosynchronis orbit, ready to float free. If
you want an orbit lower down you just burn a little rocket fuel (that
you brought up with you) to slow down & drop lower.

The other 38000 miles of line wants to pull away from the Earth so
acts as a counter weight keeping the whole thing pulling straight up.
If you keep going past the 24,000 mark before cutting loose you start
picking up the velocity you need to get to the Moon, as well as many
other fun spots around the system .

Any deflection caused by sending payloads up gets cancelled out by
stuff coming back down, i.e "My Parents Went to Jupiter & All They Got
Me Was This Cheap T-Shirt" x 10-6.

H.

"Bob Chilcoat" wrote in message ...
According to the newspaper article I read, the proposed fiber is a "tape"
roughly three feet wide and a few thou thick. A flat ribbon is
aerodynamically unstable and will vibrate axially in any wind. This thing
would seem to be the ultimate Tacoma Narrows Bridge. Just my first
impression.

The problem with the Tacoma bridge was that the materials couldn't
handle the flexing. Lots of materials are designed to vibrate -
saxophone reeds, guitar strings, etc.

So what would the pitch of this critter be, and how many Db?