Can we now build the "space tower"?

Very interesting article here reporting on researchers who had
previously announced a rapid means of producing synthetic gem sized
diamonds, now believe their methods will work to produce diamonds of
arbitrary size:

Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.
"A team led by Russell Hemley, of the Carnegie Institute of
Washington, makes diamonds by chemical vapour deposition (CVD), where
carbon atoms in a gas are deposited on a surface to produce diamond
crystals.
"The CVD process produces rapid diamond growth, but impurities from
the gas are absorbed and the diamonds take on a brownish tint.
"These defects can be purged by a costly high-pressure, high-
temperature treatment called annealing. However, only relatively small
diamonds can be produced this way: the largest so far being a 34-carat
yellow diamond about 1 centimetre wide.
Microwaved gems
"Now Hemley and his team have got around the size limit by using
microwaves to "cook" their diamonds in a hydrogen plasma at 2200 °C
but at low pressure. Diamond size is now limited only by the size of
the microwave chamber used.
"The most exciting aspect of this new annealing process is the
unlimited size of the crystals that can be treated. The breakthrough
will allow us to push to kilocarat diamonds of high optical quality,"
says Hemley's Carnegie Institute colleague Ho-kwang Mao."
http://www.newscientist.com/article/dn16036

Original research article:

Enhanced optical properties of chemical vapor deposited single crystal
diamond by low-pressure/high-temperature annealing.
Yu-fei Meng, Chih-shiue Yan, Joseph Lai, Szczesny Krasnicki, Haiyun
Shu, Thomas Yu, Qi Liang, Ho-kwang Mao, and Russell J. Hemley
Published online before print November 12, 2008, doi: 10.1073/pnas.
0808230105
PNAS November 18, 2008 vol. 105 no. 46 17620-17625
http://www.pnas.org/content/105/46/17620 [abstract]

The team's earlier research had showed they could make
synthetic diamonds of perhaps 50% greater hardness than natural
diamond. This should correspond to 50% greater compressive strength
as well.
Most discussion on the space elevator has centered on ultra strong
materials for a cable in tension. However, according to this recent
report,
synthetic diamond production can now be scaled up to arbitrarily
large sizes. So a compressive structure to space made of diamond might
be
feasible earlier, as diamond is much stronger in compression than in
tension.
I've seen various estimates for the compressive strength of natural
diamond. If we take it as 400 GPa, then a space tower of diamond would
have
characteristic length of 400x10^9 Pa/(9.8m/s^2 x 3600 kg/m^3) =
1.13x10^7
meters, or 11,300 km. If this new synthetic diamond method really
does create
diamond of 50% higher compressive strength than natural diamond, then
this
length would be 17,000 km.
And these are lengths without taper. Considering also that this
maximal
height for an untapered tower assumes constant gravity where in
actuality
the gravity is 1/16th as strong at 17,000 km altitude, it is possible
that a
tower made of diamond could reach all the way to geosynchronous
altitude
without taper.
There aren't many references on the net available that do the
calculations for
a space tower in compression as opposed to a space elevator cable in
tension.
Here's one that gives the equations and some sample calculations:

Optimal Solid Space Tower.
http://arxiv.org/abs/physics/0701093


Bob Clark

On Dec 8, 12:44*pm, Robert Clark wrote:
[snip]
Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.
[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

How does the free environment of 1e-21 bar and of truly zero gravity
sound?

The Selene/moon L1 should make rather nice for creating those nifty
diamonds.

~ Brad Guth Brad_Guth Brad.Guth BradGuth BG / “Guth Usenet�


Robert Clark wrote:
Very interesting article here reporting on researchers who had
previously announced a rapid means of producing synthetic gem sized
diamonds, now believe their methods will work to produce diamonds of
arbitrary size:

Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.
"A team led by Russell Hemley, of the Carnegie Institute of
Washington, makes diamonds by chemical vapour deposition (CVD), where
carbon atoms in a gas are deposited on a surface to produce diamond
crystals.
"The CVD process produces rapid diamond growth, but impurities from
the gas are absorbed and the diamonds take on a brownish tint.
"These defects can be purged by a costly high-pressure, high-
temperature treatment called annealing. However, only relatively small
diamonds can be produced this way: the largest so far being a 34-carat
yellow diamond about 1 centimetre wide.
Microwaved gems
"Now Hemley and his team have got around the size limit by using
microwaves to "cook" their diamonds in a hydrogen plasma at 2200 �C
but at low pressure. Diamond size is now limited only by the size of
the microwave chamber used.
"The most exciting aspect of this new annealing process is the
unlimited size of the crystals that can be treated. The breakthrough
will allow us to push to kilocarat diamonds of high optical quality,"
says Hemley's Carnegie Institute colleague Ho-kwang Mao."
http://www.newscientist.com/article/dn16036

Original research article:

Enhanced optical properties of chemical vapor deposited single crystal
diamond by low-pressure/high-temperature annealing.
Yu-fei Meng, Chih-shiue Yan, Joseph Lai, Szczesny Krasnicki, Haiyun
Shu, Thomas Yu, Qi Liang, Ho-kwang Mao, and Russell J. Hemley
Published online before print November 12, 2008, doi: 10.1073/pnas.
0808230105
PNAS November 18, 2008 vol. 105 no. 46 17620-17625
http://www.pnas.org/content/105/46/17620 [abstract]

The team's earlier research had showed they could make
synthetic diamonds of perhaps 50% greater hardness than natural
diamond. This should correspond to 50% greater compressive strength
as well.
Most discussion on the space elevator has centered on ultra strong
materials for a cable in tension. However, according to this recent
report,
synthetic diamond production can now be scaled up to arbitrarily
large sizes. So a compressive structure to space made of diamond might
be
feasible earlier, as diamond is much stronger in compression than in
tension.
I've seen various estimates for the compressive strength of natural
diamond. If we take it as 400 GPa, then a space tower of diamond would
have
characteristic length of 400x10^9 Pa/(9.8m/s^2 x 3600 kg/m^3) =
1.13x10^7
meters, or 11,300 km. If this new synthetic diamond method really
does create
diamond of 50% higher compressive strength than natural diamond, then
this
length would be 17,000 km.
And these are lengths without taper. Considering also that this
maximal
height for an untapered tower assumes constant gravity where in
actuality
the gravity is 1/16th as strong at 17,000 km altitude, it is possible
that a
tower made of diamond could reach all the way to geosynchronous
altitude
without taper.
There aren't many references on the net available that do the
calculations for
a space tower in compression as opposed to a space elevator cable in
tension.
Here's one that gives the equations and some sample calculations:

Optimal Solid Space Tower.
http://arxiv.org/abs/physics/0701093


Bob Clark

On Dec 8, 11:50 am, Puppet_Sock wrote:
On Dec 8, 12:44 pm, Robert Clark wrote:
[snip] Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.

[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

A 100 km tower of 10:1 taper should be rather easily doable.

If this tower were given a 1 km2 roof or top, that makes the base
11x11 km, and perhaps a foundation footprint upon the crust of as
little as 13x13 km.

If given the opportunity, I'll provide all the diamond you'd like.

~ Brad Guth Brad_Guth Brad.Guth BradGuth BG / “Guth Usenet”

"Puppet_Sock" wrote in message
...
On Dec 8, 12:44 pm, Robert Clark wrote:
[snip]
Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.
[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

=============================

This is really interesting. Has anyone having some knowledge
and experience in architecture actually roughed such a
structure?

If it's built, what is its ground loading? Where on the
equator, is the ground strong enough to carry this
weight? How about winds that want to topple this
structure, which seems a good bet to exert great turning
moment upon its base? ?? I.e., this is a good idea
but is it *doable*?

Titeotwawki -- mha [sci.space.policy 2008 Dec 08]

Robert Clark wrote:

The team's earlier research had showed they could make
synthetic diamonds of perhaps 50% greater hardness than
natural diamond. This should correspond to 50% greater
compressive strength as well.

Hmm, I'm not sure that's the case. In fact, I'm fairly certain that's
not the case. Hardness isn't linearly proportional to ultimate
compressive strength, is it? Or to put it another way, if it is, why
do we use two separate measurements?

Most discussion on the space elevator has centered on ultra
strong materials for a cable in tension.

There's a very good reason for this: buckling. You're proposing a very
very tall, thin tower acting in compression, and assuming the failure
mode is pure compression. It's not (not even close).

While we're at it, making the bottom so that it won't fail in
compression isn't going to do you much good if the rocks under it
will... In short, it's not the compressive strength of diamond you
have to worry about here, as it's not what will limit it.

--
Brian Davis

On Dec 8, 1:26 pm, "Martha Adams" wrote:
"Puppet_Sock" wrote in message

...
On Dec 8, 12:44 pm, Robert Clark wrote:
[snip] Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.

[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

=============================

This is really interesting. Has anyone having some knowledge
and experience in architecture actually roughed such a
structure?

If it's built, what is its ground loading? Where on the
equator, is the ground strong enough to carry this
weight? How about winds that want to topple this
structure, which seems a good bet to exert great turning
moment upon its base? ?? I.e., this is a good idea
but is it *doable*?

Titeotwawki -- mha [sci.space.policy 2008 Dec 08]

It's doable. However, seems nearly everyone is deathly afraid of the
big bad wolf.

I'd posted my 100 mile high structure as a topic, and lo and behold,
every brown-nosed clown within Usenet came out to play, or rather to
topic/author stalk and bash for all they could muster. Otherwise my
topic was banished and/or officially ignored as best they could
manage.

~ BG

On Dec 8, 4:26*pm, "Martha Adams" wrote:

This is really interesting. *Has anyone having some
knowledge and experience in architecture actually
roughed such a structure?

Yes; tall structures have popped up now and then, but never to my
knowledge in reference to geosync. Even for shorter distance,
dynamically-supported structures tend to be more favored (mostly
because the materials requirements in question are much more
tractable).

If it's built, what is its ground loading?

Depends rather strongly on how it's built, but the ground loading is
very high. There is the question of how long you need it to stand, of
course (mountains can't be supported by crustal strength, but that
doesn't mean you can't drop a mountain-sized load on the crust - it's
sag and flow, but on long timescales).

How about winds that want to topple this structure...

Considering the fact that such a structure would be multiple (10, in
this example) kilometers on a side, and the winds in question are only
even a minor issue in the lowest 10-20 km of the atmosphere, I'd say
wind loading "tipping" such a structure is pretty much a non-issue...

*I.e., this is a good idea but is it *doable*?

I can't see any reason to do it, when much better methods (i.e.,
tensional structures) could be build for a small fraction of the
materials cost, and would be safer to boot. For very short towers
(kilometer to 10 km?), perhaps... although still largely silly. guy
wires will only get you so far... and then you start thinking about
why you didn't make the entire thing a guy wire in the first place.

--
Brian Davis

On Dec 8, 2:50*pm, Puppet_Sock wrote:
On Dec 8, 12:44*pm, Robert Clark wrote:
[snip] Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.

[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

Not for an elevator cable in tension, but they are for a tower
structure in compression.
See the calculations he

Optimal Solid Space Tower.
http://arxiv.org/abs/physics/0701093

Bob Clark

On Dec 8, 4:05 pm, Robert Clark wrote:
On Dec 8, 2:50 pm, Puppet_Sock wrote:



On Dec 8, 12:44 pm, Robert Clark wrote:
[snip] Artificial diamonds - now available in extra large.
18:11 13 November 2008 by Catherine Brahic.
"A team in the US has brought the world one step closer to cheap,
mass-
produced, perfect diamonds. The improvement also means there is no
theoretical limit on the size of diamonds that can be grown in the
lab.

[snap]

While that's quite interesting, there's a huge gap between
big cheap diamond crystals and an orbital tower.

I'm not even sure diamonds are strong enough. IIRC, they
fall short quite a bit.
Socks

Not for an elevator cable in tension, but they are for a tower
structure in compression.
See the calculations he

Optimal Solid Space Tower.http://arxiv.org/abs/physics/0701093

Bob Clark

I fully agree. A tower with a 10:1 taper and a substantial foundation
that's situated on the bedrock/crust can in fact be created for the
100 km or greater vertical dimension.

Some areas of Earth's crust are certainly much thicker and more
capable of sustaining the added mass of your tower.

~ BG