Re: Methane threatens to bake humanity like Turkeys in an Oven

Sorry for the delay, this reply seems to have
failed to reach the server too.

"Ian Parker" <ianparker2@xxxxxxxxx> wrote in message
news:1171124071.381360.103270@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 10 Feb, 11:53, "George Dishman" <geo...@xxxxxxxxxxxxxxxxx> wrote:
"Ian Parker" <ianpark...@xxxxxxxxx> wrote in message
....
My rotation in a year was an estimate of the rough magnitude of tidal
forces on an L1 Now you can have a structure at 55Kg/km^2 in tension
quite easily, ...

No you can't. Here is the lowest areal density material
I know of

http://www.space.com/businesstechnology/technology/carbonsail_000302....

Let me tell you a secret. 55kg/km is in fact not my figure. This topic
was discussed in sci.space.policy. Most oof the contributers had the
idea of transporting material from Earth using rockets. All the
material - not just chips and critical parts. If you say 55kg/km^2 is
unrealistic I am not going to argue with you - but it makes total
transportation from Earth unrealistic.

Agreed.

If you have a machine of
exponential growth then weight does not matter in the same way. You
will go for MEO.

The choice between MEO and L1 is probably not driven
primarily by mass. MEO has concerns with such a large
number of objects in orbit in regard to making the
system stable in the event of an individual plate
having a guidance fault. See the thread entitled
"Orbiting Junk, Once a Nuisance, Is Now a Threat"

They have achieved 5 gsm, compared to 80 gsm for typical
office paper. That is 5000 kg/km^2 (5 tonne/km^2) so
55 kg/km^2 is two orders of magnitude less than credible.

Replication is not relevant, you are making thin panels
which have no capability to reproduce because that extra
function would increase the mass. Besides which, we do not
have self-replicating technology in any form, nor are we
going to have it in the timescales of the possible methane
problem.

It is not. A CAD/CAM based VN not only replicates it also makes
anything that is compliant.

We use CAD/CAM at work to make a variety of metalwork
and have used it on occassion for rapid prototyping
where any arbitrary shape can be made using UV setting
to produce a mould, but it's uses are very limited and
the technique is extremely expensive. You seem to have
a very odd idea of what it can do.

To produce vast numbers of thin plates either to
assemble into a single rigid shield at L1 or for a
Dyson swarm, you need a factory churning out those
plates, not more machines. Those factories would
need to be lifted from Earth because you have a
chicken-and-egg situation, there are no factories
in space capable of making factories, and there's
no sense using replication because the equipment
needed to manufacture all the parts of the factory
would be quite different from what is needed to
churn out the shield plates.

3) I think we have a little bit of confusion about 5km/h. It does not
matter how large a structure is. The important thing is the speed an
object attains in traversing it. If we build a brick wall 5m high at
10m/s^2 (10 = R&R 9.81) we have 10m/s or 18km/h.

Yes, and if your shield passes the Earth edge on it is 600km
"high". If the centre is in freefall, what is the gravity at
the top and bottom? What speed do you attain falling from the
centre to the bottom (the edge nearest the Earth)?

If you have the sunshield at L1 the answer id something like 5km/h. I
mentioned a year as being the critical time at L1. Forces there are
very small.

I agree, that's not what I was discussing.

Getting there? The assembly would be folded.

Yes, or better sent as panels for assembly in situ. You
can set up the factory near Earth and send individual
panels which are added to the structure at L1 over some
time. What that means though is that you first locate an
asteroid of several million tonnes and bring it into
Earth orbit, then process it into panels and send them
either into individual Earth orbits or for assemble at L1.

What I was talking about some posts back was the tidal
problem if you made the entire assembly elsewhere and
tried to bring it into L1.

More importantly, with an areal density of 5 tonne/km^2, what
is the tension at the centre?

The important parameter is the free fall speed. At the center the
force is compressive.

Yes, once it is at L1. It would be tension from tidal
force as a completed L1 shield was manouvered past the
Earth to get it into location.

A tiny fraction of the cost of building smelters and
manufacturing plant to process your asteroid in
orbit. The ISS would be nothing more than a
proof-of-concept prototype for your idea.

The return to the Moon is in fact proposing just that smelters. Ca you
build a smelter that is small?

You can, but at 5 tonne/km^2, a 700km diameter shield
has a mass of nearly 2 million tonne. Unless each
smelter load has a significant mass, the loading and
unloading times become dominant and even a large
number of smelters will be too slow. Before you go
off on a tangent about replication, forget it. Smelters
don't make more smelters, they just extract raw material.

I think we shold be clear about what we would be trying to achieve.

Yes. You are trying to create a sunshield, nothing more.
You have suggested VN as a means to that end only and
I have pointed out that we do not have a capability of
self-replication in any form whatsoever

A VN system takes in raw material and replicates. The replication is
complete. If we have smelters we produce more smelters.

No, a smelter takes in ore and produces pig metal. A VN
machine would take in pre-processed components and turn
them into a copy of itself which could also act as a
smelter. The downside is that it needs components to
assemble which you don't have and the vast majority of
the final item would be geared to the more complex task
of replication, not smelting. A smelter need only be
some refractory container, a large mirror, some means of
separating the products when in liquid phase (there's no
gravity so maybe it has to rotate like a centrifuge) and
methods for loading and unloading.

As I said I
should have talked about VN swarms rather than VN machines. Each
entity in a swarm and a smelter is an entity is produced by other
entities. A swarm is a VN swarm if the inputs left after subtracting
outputs from other elements are basic inputs.

In fact industry on Earth is a kind of VN swarm. We have industry
where basic raw materials form products. We have all the machines
needed to produce the machines. If we have a flatpack assembler a
closed loop (potentially) exists on Earth.

Exactly. Now you have a choice:

a) create a copy of all of that in space and put all
the thousands of people needed to run it up there

b) keep the industry down here and only lift the end
product, the shield panels

c) produce the simplest and lightest factory capable
of making shield panels and lift it flatpack into
space. Assemble it there and start processing the
asteroidal material into panels.

My money would be on (c) but it is still sci-fi nonsense,
there's no way we could bring a 2 million tonne asteroid
into Earth orbit for processing and the costs would be far
beyond anything we could afford.

Compared to giving some small seed grants to farmers to
produce bio-fuel and requiring car manufacturers to
raise the proportion of bio-fuel that can be used
without invalidatiing the warranty (currently 5 or 10%),
any sort of sunshield idea is totally nuts.

If you are talking about building a
sunshield you can have small pieces (even down to a cm^2) and small
tools. If you are talking about high temperature processes there is a
minimum size required. For low temperature processes you cut the
sizeProbably the best answer within current technological capabilities
is to heat by directing sunlight onto the furnace.

Again, that is all sci-fi wishful thinking, we don't
have low temperature processes for separating rocks
into their constituent element and we aren't going
to have them any time in the next couple of decades.

Why do you need low temperature processes.

Look back two paragraphs, you suggested it.

I will accept that seed
sizes can be reduced for a pure low temperature route. But even if the
seed is 100 tons or so that is still within current lift capability.

Get it into your head that we do not have self-replication
and we will not have it at the level of processing millions
of tonnes of asteroidal material in space in a time scale
that can help with this problem. The methane will be released,
do whatever it will to the atmosphere, and dissipate naturally
before we have anything like that technology even in the lab.

As I have explained nanotechnology is suspect because we want to build
any CAD/CAM object which is compliant, but it is useful for certain
processes. Clearly the further we can minaturize the basic seed the
lower will be the launch cost. Of corse because of thermal
considerations a high temperature process has an intrinsic size.
Throughout the years the size of electronic components has steadily
gone down,

Yes, but the temperature needed to grow a silicon
crystal hasn't changed.

True. Initially a few critical components would come from Earth. This
would be reduced as time went on.

No it wouldn't because what is sent up from Earth would
not be able to produce the huge silicon fab plants we
have here on Earth. Nor can you find the high quality
white silica sand they rely on in asteroids.

but we have a long way to go to DNA where a sperm contains
4GB (a DVD).

A far lower sum
would bring capabilities up. You are right though to focus on the
low
level of achievment of NASA.

I never mentioned them, you keep ranting on about
them. I'm not interested in your political ravings.

I think it iss fair comment.

Given that you need a space-based manufacturing plant
capable of processing millions of tonnes of material
in just a few years, the ISS pales into insignificance.
It is a tiny proof-of-concept demonstrator, and cost
efficiencies on your vastly larger plant would be even
worse. It is unlikely it could survive in low orbit and
probably construction at an Earth moon Lagrange point
or farther away would be essential to avoid tidal force
problems.

The ISS is being built by transport from Earth. This is a totally
different concept.

Nope, it's exactly the same, the whole plant would
need to be lifted because it will only produce shield
panels, not more plants.

Sure, we can calculate all sorts of complex stuff, but
a calculation never repaired a toaster, you need the
ability to manipulate material before any of that is
of any use.

Lets reduce this to its basics. NASA in its heady days was proposing
space colonies where the standard flatpack assembler was called an
astronaut. In discussing complex equations I was merely looking at
what you would need to replicate an astronauts assembing capabilities.
My claim is that the problem is not that complicated and can be solved
by basic analytical techniques.

And my point is that solving equation doesn't produce
anything, Sonic the Hedgehog cannot bend a paper clip.
You are burying your head in the sand and totally
ignoring the real problem, that of physical manufacture.

You still have your head in the sand. A seed is of
no use whatsoever unless there are pre-processed
raw materials in a form that can be assembled into
a copy of the seed, and they don't exist.

What about all the extractive technology here on Earth. It is an
example of an extracting and replicating system?

No, it is an example of many individual non-replicating
systems and all of them use specialised raw materials.
Aluminium extraction requires bauxite, iron comes from
iron ore, silicon chips from white sand and so on. As
those raw materials run out, the price goes up because
we cannot extract elements from random sources. Asteroids
were one of the first sources of iron but many of the
materials in modern technology are highly specialised
and are not going to be available in space.

I will however
concede one point. If we could substitute LOW temperature processes
for high temperature ones extractive industry would be made much more
efficient. This is so both in Space and on Earth. Rio Tinto and other
mining companies should be "carrying on up the Amazon". "Carry on up
the Amazon" is of course a crude statement. It implies that we are
simply gathering DNA and splicing large strands into our organism. In
the future (I am not stipulating this as essential for the basic
project) we will be able to produce a sequence theoretically and make
it in a gene sequencer.

Sure but that technology still only conveys data, it
needs living cells to effect any useful work and that's
where your ideas collapse every time, you have no
effectors.

Stanford and Cornell are doing a great job - don't get me wrong.

I agree, but the fact remains that there is a huge gap
between where they are now and what is needed to
manufacture anything using atomic scale methods.

You don't need atomic scale models.

Yes you do. Either that or large plant with multiple
stages to smelt and refine rubble into usable material
followed by a series of piece-part manufacturing
processes and finally assembly. Bacteria and enzymes
and other molecular processes are the only way to
extract minerals at low temperature.

It is better, I will concede but NOT essential.

Not essential, but without it you have a high temperature
process or perhaps a chemical process, extracing metals
with acids for example. The problem then is where you
get the reagents. You have to work out a complete
chain of processes to solve this problem. If you shield
pnels are purely carbon composites like the material I
showed you then you only need a single extraction process.
Adding on to that all the processes to extract all the
materials needed to replicate the factory that does the
extraction _vastly_ increases the problem. Just take a
trivial example, the latest chips are yusing Hafnium as
a dielectric. Do you think it is worth setting up an
extraction plant to find Hafnium in asteroids to make the
system self-replicating or do we just lift the material
from Earth? The same goes for all the dozens of other
elements needed.

You have to build a furnace using CAD/CAM.

Nonsense. Do you think the 19th century furnaces used
CAD/CAM? Do you _design_ one with CAD if you want but
it is the "M" part where the problem lies. No amount
of "CA" will help if you don't have a way to manipulate
the matter.

Yes but we don't use 19th century furnaces today.

You don't "have to".

Does this matter if you have replication?

We don't.

I know, they is the key step that has to be taken.

And Cornell is typical of how close we have got in
the last few decades. Take a look at the materials
used to make each of the blocks and see if you can
work out how close the final assembly is to being
something that can pick up a piece of asteroid and
creat all the plastic, gears, motors and controlling
computers that are needed to make another block.

http://www.news.cornell.edu/stories/May05/selfrep.ws.html

We are many decades away from the solution, far beyond
any useful timescales for the possible methane threat.

Smelting that much aluminium out of asteroidal rock
is not going to be done by Sonic the Hedgehog, even
if he can use Javalink.

2, 4 8 etc. Sonics will.

No, no matter how many you have, they remain just
pixels on a screen with no ability to influence
real matter in any way. I think you have been
playing too many computer games and are losing the
distinction between them and real life. An infinite
number of Sonics couldn't band a paper clip.

The interesting thing obout Sonic and about games is that the Pentagon
is proposing to base the latest generation of its ground automation
weapons on AI ideas pioneered by games. ...

Still intent on sticking your head in the sand Ian?
All the AI in the world doesn't move you forward one
iota without there being some physical system for it
to control. Sonic cannot bend a paper clip and you
have no answer to that problem.

George


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