Space elevator now possible?

On 25 Jul 2003 22:40:14 -0700, (Double-A) wrote:

(Robert Clark) wrote in message om...
Space Elevators Maybe Closer To Reality Than Imagined
by Richard Perry
Los Angeles - Jul 22, 2003
http://www.spacedaily.com/news/materials-03w.html


Bob Clark


Consider Nextel's new 400,000-foot high communications tower for
providing coast-to-coast walkie-talkie service! (Chuckle, snicker,
snort!) Tesla would have been envious!


It beats them thar antenna deer. Walkin all over the country just
so some city slicker can make them annoying chripin sounds!
Can't even shoot 'em. Outta be a law again it.





--
Dr.Postman USPS, MBMC, BsD; "Disgruntled, But Unarmed"
Member,Board of Directors of afa-b, SKEP-TI-CULT® member #15-51506-253.
You can email me at: eckles(at)midsouth.rr.com

"The services provided by Sylvia Browne Corporation are highly
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On Sat, 26 Jul 2003 01:43:59 -0500, "Paul F. Dietz"
wrote:

Double-A wrote:

Consider Nextel's new 400,000-foot high communications tower for
providing coast-to-coast walkie-talkie service! (Chuckle, snicker,
snort!) Tesla would have been envious!

Nah, that's clearly ridiculous and fictional.

It's actually the antennalopes.

Paul



Daymn. I wasn't paying close enough attention. I thought they were
deer.




--
Dr.Postman USPS, MBMC, BsD; "Disgruntled, But Unarmed"
Member,Board of Directors of afa-b, SKEP-TI-CULT® member #15-51506-253.
You can email me at: eckles(at)midsouth.rr.com

"The services provided by Sylvia Browne Corporation are highly
speculative in nature and we do not guarantee that the results
of our work will be satisfactory to a client."
-Sylvia's Refund Policy

"Paul F. Dietz" wrote in message
...

Deer me. Given their electronic enhancements, they're actually e-lopes.

Well, I'm hearing of places using devices to block cell phones and the
"walkie-talkie" stuff. I think they are using anti-lopes.



Paul

"Cardman" wrote in message
...

Also just how fast would a trip to 37,000 km take? I guess that
depends on how fast you want to go, where 2 to 3g seems about as fast
as some passengers could handle. Although it could go faster higher
up.

Please expand.

And how high could you go if you are running a cable up to about
91,000 km? As of course near the top it would start bending.

Please expand.

DrPostman wrote:

On 25 Jul 2003 08:59:34 -0700, (Robert Clark)
wrote:

Space Elevators Maybe Closer To Reality Than Imagined
by Richard Perry
Los Angeles - Jul 22, 2003
http://www.spacedaily.com/news/materials-03w.html


Bob Clark

Can anyone explain to me why you would HAVE to have mach 16
speed vehicles to mate up with non-fixed tethers? I have always
seen that as a better idea to the space elevator attached to the
Earth, but I never knew it would require such great speeds to
work. I even thought the idea of a set of these between worlds,
wipways, if you will, to be a interesting way of spacecraft propulsion
through our system. I am not an engineer or a scientist, so if you
could keep the explanation dumbed down a bit I would appreciate it.

How many terrestrial suspension bridges are being planned based on
SuperDooper Fiber? If private ownerhsip cannot see a profit, then
government sure as Hell can't see a profit.

The high end is somewhere around geosynchrous orbit. That's about
Mach 16 vs. the ground. Low Earth orbit is about Mach 25. No matter
how one runs the numbers - cost, reliability, local and space weather,
usablity, fabrication, center of mass balancing the silly thing, raw
solar ultraviolet degradation, ozone degradation, vulnerability to
"political statements" - it is a perfect NASA project: an utter white
elephant with men (minorities, schoolmarms, political debts) inserted.

Anybody who would trust their lives to a currently technologically
non-existent filament loaded to 90+% of its optimistically spec'd
static tensile strength when new had best look at NASA "studies" of
deployed tethers in space. Can anybody name a succssful deployment?
Trusting your life to a poly(vinyl alcohol)-built fiber is ludicrous.
PVA is water-soluble (lower atmosphere, including "sea deployments."
It doesn't like heat (raw sunshine) either.

Have you ever worked with composites? What are the chances of
spinning 25,000 miles of perfect filament? Will you trust the
splices? What is the catastrophic failure rate for the tiny low-tech
bull**** political boondoggle Space Scuttle? Feynman estimated about
1%. That has been holding nicely.

First, we find Superman. Second, we get him to grow his hair real
long (Project Rapunzel; massive red kryptonite R&D). Third...

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

In sci.physics, Robert Clark

wrote
on 25 Jul 2003 08:59:34 -0700
:
Space Elevators Maybe Closer To Reality Than Imagined
by Richard Perry
Los Angeles - Jul 22, 2003
http://www.spacedaily.com/news/materials-03w.html


Bob Clark

Bond energy of C-C: 348 kJ/mol
Bond length of C-C: 154 pm

That bond energy is in a slightly inconvenient form, so we
convert by dividing by Avogadro's Number (6.022 * 10^23 atoms/mol).
This yields 5.779 * 10^-19 J per actual bond, or 3.607 eV.

A carbon atom weighs 1.993 * 10^-26 kg. On Earth the carbon
atom experiences a grav force of about 1.954 * 10^-25 N.
If one were to (somehow) hold onto both carbon atoms and
apply a certain force, when would the bond snap and the atoms
become free (or at least bound to other atoms)?

I wish I knew offhand. Assuming one has a monocarbon bond
line (otherwise known as an insanely long hydrocarbon!)
one would have a total mass of 14 / 6.022*10^23 / (1.54*10^-10)
= 1.51 * 10^-13 grams/meter. (Remember the hydrogen atoms;
that's why 14, not 12.) Of course this is assuming linear
bonds, which isn't quite right as carbon is generally tetrahedral;
the effect would be somewhat like that of a zigzag. Coiling
such a line would probably be disastrous. :-)

In any event, even were one to have a space elevator,
one wouldn't save that much energy. It turns out that
lifting a mass of 1 kg 200 km out of the Earth's grav
field would cost

GmM / d - GmM/(d+h) = 1.905*10^6 J.

where d is the Earth's radius, which I'm taking to be 6.378*10^6 m.

The shuttle does this more or less routinely, of course, at great
expense per launch.

Synchronous orbit is where sqrt(G*M/r) = 2 * pi * r / t,
or G*M/r^3 = 4 * pi^2 / t^2, or r = (G*M*t^2 / (4 * pi^2))^(1/3)
= 4.228 * 10^7 m.

To raise a 1 kg mass to this orbit would require 5.321 * 10^7 J.

Angular velocity may not be a problem during this ascent, but
regular velocity is. On Earth, we're moving around (on
the Equator, anyway) at a speed of 6.378*10^6 * 2 * pi / 86400
= 463.8 m/s. Or, if you prefer, the terminator (the boundary
between night and day) is moving east to west at this speed.
(Or we're moving west to east.)

A 1 kg mass sitting on the Earth has a de facto energy
of 1/2 m v^2 = 108,000 J just sitting there. (Not much
it can do with it, admittedly.) Boost that same mass
to our equatorial geosynch elevator terminus and it now
has to move at a velocity of sqrt(G*M/r) = 3,075 m/s.
The kinetic energy is now 4,726,000 J.

The elevator would save *nothing* on energy costs regarding
the payload mass. I'd have to compute how much energy
one might save regarding reactive mass expenditures.
That reactive mass has energy too -- wasted energy, in
many respects, but it's the only method we know of by
which one can acquire the needed velocity or momentum to
achieve orbit. Of course one might have to string a power
cable, and given the electric field in the van Allen belts,
is that really such a hot idea? And there are a number
of other phenomena such as those peculiar red plumes we
see on occasion high in the ionosphere; we've never had
to worry about launching in a thunderstorm but this
hypothetical elevator will have to weather all kinds of
weather, possibly including cyclones.

And then there's the question of angular momentum. The mass
on Earth has to increase angular momentum in order to get
into space on this elevator, unless one wants to risk deorbiting
the satellite by slowing it down. I've no idea how one might
borrow angular momentum from the Earth in order to do this,
apart from making that dangling flexible line into some sort
of rigid truss; at least that way the base can impart a force
on the Earth to slow it down to compensate.

Sorry, Arthur C. Clarke. :-) Assuming he's the original
proposer of this thing. It's the first place I've seen it,
anyway; he proposes a monofilament band and a bank of
batteries to power the elevator. I don't know if batteries
will be enough to make up the energy deficit. I'm not even
sure a gasoline motor can do it, although I'd have to work
it out; that 45 MJ/kg cited for chemical energy from the
gas does not include the oxygen required to burn it.

--
#191,
It's still legal to go .sigless.

And then there's the question of angular momentum. The mass
on Earth has to increase angular momentum in order to get
into space on this elevator, unless one wants to risk deorbiting
the satellite by slowing it down. I've no idea how one might
borrow angular momentum from the Earth in order to do this,


What happens when a figure skater is sinning rapidly on the surface of the ice
and then extends her arms? She is borrowing angular momentum from her central
torso and sending it out to her arms, hands, and finger tips, if you don't know
how to do this, you'll never learn to skate.

apart from making that dangling flexible line into some sort
of rigid truss; at least that way the base can impart a force
on the Earth to slow it down to compensate.

Are you forgetting that recent discover about centrifugal force causes my
circular movement. When you are driving your car down a highway and you make a
sudden turn what happens to those passengers in your car who aren't wearing
their seat belts? This is called centrifugal force. Without centrifugal force a
cowboy would not be able to swing a rope around over his head and rope a steer,
he would not be able to transfer the angular momentum from his arm to the rope.

Tom

"Paul F. Dietz" wrote in message
...
TKalbfus wrote:

What happens when a figure skater is sinning rapidly on the surface of
the ice
and then extends her arms?

They put dollars in her G string?


If she spins fast enough does she reach 2 or 3 G?


Paul

(Robert Clark) wrote in message om...
Space Elevators Maybe Closer To Reality Than Imagined
by Richard Perry
Los Angeles - Jul 22, 2003
http://www.spacedaily.com/news/materials-03w.html


Bob Clark



Has anyone considered the problem of vibrations? High-speed jet
stream winds blowing past the cable could have the same effect as a
bow being pulled across a violin string. Harmonic vibrations could
build up to incredible intensities! Enduring the hum of the world's
largest stringed instrument could be unpleasant. Riding up upon its
vibrating string could be catasrophic!

Double-A

Uncle Al wrote in message
...
First, we find Superman. Second, we get him to grow his hair real
long (Project Rapunzel; massive red kryptonite R&D). Third...

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!


"Sure it could be done if we weren't so stoooopid and do you know haaaarrd
it would be."

There isn't any better way to do it. Quit yer whining.