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Can we now build the "space tower"?



 
 
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  #101  
Old December 17th 08, 10:25 AM posted to sci.astro,sci.space.policy,rec.arts.sf.science
Eivind
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Posts: 8
Default Can we now build the "space tower"?

Brian Davis skreiv:

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower.


It's sillier than that even. Because wind-load scales proportionally to
diameter, more or less, this means larger structures are less influenced
by wind than small structures.

If you make a tower that is 10 times as large in every direction, then
the wind-load is also (on the order of) 10 times as large, (assuming the
wind only hits the lower X kilometres of it) however the cross-section,
influencing strength and stiffness, is 100 times as large.

We're talking a tower that is 10kmx10km on the lower part here, it's
gigantic. I'm fairly sure wind-load is completely down in the noise for
such a structure.


Eivind
  #102  
Old December 17th 08, 10:29 AM posted to sci.astro,rec.arts.sf.science
Eivind
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Posts: 8
Default Can we now build the "space tower"?

YKhan skreiv:

Diamond is not anymore or less worthless than gravel is, until you mix
gravel into concrete. Or sand is worthless until you melt it into
computer chip wafers. But diamond as simply a pretty thing to wear?
Worthless.


I'm confused now. Could you please explain what, precisely, you mean
when you say that something has 'value' ? (I'm assuming that by
'worthless' you mean 'of zero or very low value')


Eivind
  #103  
Old December 17th 08, 10:59 AM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
IanM
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Default Can we now build the "space tower"?

Yousuf Khan wrote:

Diamonds are already a commodity, except we
weren't allowed to know.

There is no reason why anyone should worship this worthless shiny stone.
This stone whose most useful purpose is as a material for cutting and
abrading equipment. Until we can find ways of harnessing degenerate
matter from dwarf stars or neutron stars, it's our hardest known material.


*wrong* google Rhenium Diboride, its *HARDER* ;-)
  #104  
Old December 17th 08, 12:14 PM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
Fred J. McCall[_3_]
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Posts: 10,018
Default Can we now build the "space tower"?

Erik Max Francis wrote:

:YKhan wrote:
:
: Sure, that's why I said "until" which has an implied "if" in there.
: Anyways, I can see even unstable degenerate matter as useful, if only
: as concentrated explosives that can blow a hole through any normal
: matter. This stuff should pack more energy than either nuclear fission
: or fusion, but less than matter-antimatter reactions.
:
:Now you're talking about something else; earlier you said they would
:"hard." Degenerate matter has no "hardness." It's dense because there
:is a huge amount of mass compacting it into a degenerate state. That
:mass doesn't give it hardness, it just makes it dense. Hardness and
:density are not the same thing.
:

For an every day example of this, look at lead (or gold). Both quite
dense. Both quite soft.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
  #105  
Old December 17th 08, 04:47 PM posted to sci.astro,sci.space.policy,rec.arts.sf.science
BradGuth
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Posts: 21,544
Default Can we now build the "space tower"?

On Dec 17, 1:25 am, Eivind wrote:
Brian Davis skreiv:

I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower.


It's sillier than that even. Because wind-load scales proportionally to
diameter, more or less, this means larger structures are less influenced
by wind than small structures.

If you make a tower that is 10 times as large in every direction, then
the wind-load is also (on the order of) 10 times as large, (assuming the
wind only hits the lower X kilometres of it) however the cross-section,
influencing strength and stiffness, is 100 times as large.

We're talking a tower that is 10kmx10km on the lower part here, it's
gigantic. I'm fairly sure wind-load is completely down in the noise for
such a structure.

Eivind


Correct. as like a mountain, it'll create it's own weather.

~ BG
  #106  
Old December 17th 08, 04:51 PM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
Michael Ash
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Posts: 128
Default Can we now build the "space tower"?

In rec.arts.sf.science BradGuth wrote:
On Dec 16, 7:14 pm, Michael Ash wrote:
In rec.arts.sf.science BradGuth wrote:


On Dec 16, 12:37 pm, Michael Ash wrote:
In rec.arts.sf.science Brian Davis wrote:
On Dec 15, 8:20?pm, Yousuf Khan wrote:


At around 10-15 km up, they will be contending against
the Jet Stream, sometimes reaching upto 400 km/h.


I always find it humorous that when talking about very tall, space-
elevator-style constructions, the terrifying jet stream always seems
to pop up. For a structure in compression 150 km high, any minor force
exerted by the wind below 10 km is literally going to be like a high-
velocity wind directed at my ankles: locally something to be concerned
about, but not a factor for the tower. And for tensional
(conventional) space elevators, it's even sillier: you build them at
the equator, and their minimum cross-section is down in the "turbulent
ten" lowest kilometers. Besides which, there is no jet stream at the
equator. Sigh... invoking non-applicable threats into situations where
they wouldn't matter much anyway really doesn't inspire confidence in
the line of reasoning.


I think people also forget about the effect of atmospheric density. Jet
streams are fast but they aren't all *that* strong. They're very high and
therefore are in very thin air, which substantially reduces the force that
they will impart to anything they encounter.


Typical skyscrapers are built to withstand hurricane-force winds, which
happen at sea level and are therefore more forceful. Those winds also act
along the entire height of the skyscraper instead of just some small
portion, which as you point out makes them even less significant.


Spooks, moles and MIB of the mainstream status quo have license to
kill.


That's, er, fascinating, but what's it got to do with jet streams or space
towers or, well, *anything*?


A space tower or much less my LSE-CM/ISS doesn't fit into that box of
yours, does it.

If some outsider is rocking that mainstream boat, the first thing
folks tend to do is send in the clowns, and if that doesn't work they
release those pesky MIB.


Oh I get it, you think I sent the spooks after you to shut you up!

How quaint? Don't you crazy people ever come up with anything *new*?

By the way, while you're being crazy, do you think you could stop quoting
my signature? It looks silly and serves no useful purpose.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon
  #108  
Old December 18th 08, 05:44 AM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
Alain Fournier[_2_]
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Posts: 373
Default Can we now build the "space tower"?

Yousuf Khan wrote:
Rock Brentwood wrote:

It was built in the vicinity of a large volcano, called Mount Doom,
and its construction was said to lead directly to a profusion of
languages (hence the alternate designation 'Babel'), including Elvish,
Orcish, Entish, and the other languages accounted for in the latter-
day trilogy.

From that day onward, people have looked upon the notion of a tower
reaching the heavens with fear and trepidation.



I'm sure we can handle a couple hundred more languages. :-)


Wow, handling a couple hundred more languages amazing!
Watakushi wa, go gengo ga muzukashi desu*. Parfois je męle
différentes langues**. Ciň puň fare confusione†. Ich könnte
hundert Sprache nie beherrschen††. :-)

* Me, I have trouble with five.
** Sometimes I mix different languages.
† That can bring some confusion.
†† I could never handle a hundred language.


Alain Fournier
  #109  
Old December 18th 08, 07:10 AM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
BradGuth
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Posts: 21,544
Default Can we now build the "space tower"?

On Dec 17, 7:51*am, Michael Ash wrote:

Oh I get it, you think I sent the spooks after you to shut you up!

How quaint? Don't you crazy people ever come up with anything *new*?

By the way, while you're being crazy, do you think you could stop quoting
my signature? It looks silly and serves no useful purpose.


The funny thing is, you're serious.

I have a few zingers, but what's the point?

Do you have any idea how much of our hard earned public loot per
second (including inflation) is getting used as mainstream toilet
paper?

~ BG
  #110  
Old December 18th 08, 10:32 AM posted to sci.materials,sci.astro,sci.physics,sci.space.policy,rec.arts.sf.science
Erik Max Francis
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Posts: 345
Default Can we now build the "space tower"?

BradGuth wrote:

On Dec 17, 7:51 am, Michael Ash wrote:
Oh I get it, you think I sent the spooks after you to shut you up!

How quaint? Don't you crazy people ever come up with anything *new*?

By the way, while you're being crazy, do you think you could stop quoting
my signature? It looks silly and serves no useful purpose.


The funny thing is, you're serious.

I have a few zingers, but what's the point?


They probably mention "MIB" again, which is exactly the point.

--
Erik Max Francis && && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
It's funny when you think about it / How coincidence rules
-- Anggun
 




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