Construction Platform

On 2004-07-26, John Doe wrote:
"Greg D. Moore (Strider)" wrote:
I can't think of too many cities that were built for the sole purpose
supporting a single purpose.

Most mining towns in Canada and countries such as Australia and Russia are
single purpose towns often built by the mining company. And there have been
many examples of towns litterally closing down when the mine shuts down.

Also, if you look at Baikonour, isn't that a single purpose town ?

Building an assembly plant on the moon is ludicrous. It will be far easier to
assemble something in earth orbit since you don't need mega powerful hydraulic
systems to move modules around as you would in a gravity environment.

Cranes are not exactly bleeding-edge complexity, mark you.

Yeah, it's easier to shift big heavy things in freefall. But it's
massively harder to do simple technical work in freefall and in vacuum,
it's much more tiring on your workers, there's a lot of nasty
constraints that can be avoided by simply having a gravity well and a
nice hard floor to work on.

Admittedly, the Moon is not a great solution either; it still needs
pressure suits for external work, being essentially vacuum, you still
have a lot of the thermal problems (and some new ones), but... It's
misleading to pick one point and use that as an example. The enviroment
we can work in most efficiently is a warehouse on the surface here, but
that still doesn't make it optimal g

--
-Andrew Gray

Andrew Gray wrote:

On 2004-07-26, John Doe wrote:
"Greg D. Moore (Strider)" wrote:


Building an assembly plant on the moon is ludicrous. It will be far easier to
assemble something in earth orbit since you don't need mega powerful hydraulic
systems to move modules around as you would in a gravity environment.

Cranes are not exactly bleeding-edge complexity, mark you.


Nor are the need to provide for them particularly onerous. The pumps
for those cranes that haul around city-block-sized chunks of aircraft
carrier
(http://www.nn.northropgrumman.com/ph.../C98-559-1.JPG)
while physically large, they aren't particularly bleeding edge. Nor
is the electric tram systems use to haul around huge chunks of
submarine
(http://www.virginiabase.org/Imported...nstruction.jpg)
exactly unusual.

D.
--
Touch-twice life. Eat. Drink. Laugh.

Derek Lyons wrote:
Nor are the need to provide for them particularly onerous. The pumps
for those cranes that haul around city-block-sized chunks of aircraft
carrier
(http://www.nn.northropgrumman.com/ph.../C98-559-1.JPG)


The motor may not be onerous. But the structures needed to lift it are. Just
how are you going to send wuch a large crane structure to the moon surface ?
Will you need another crane to lift that crane up into position while a bunch
of astronauts climb onto to it to make the final welds ?

Compare this with a canadarm style device that is sufficient for LEO assembly.

Note that while it is true that working in 0g is not as efficient as working
in 1g, if more of the modules are outfitted on the ground and the work in 0g
is more of a plugging the modules together type, the inefficiencies of 0g are
much less.

Also, consider that some tasks are easier in 0g. Consider placing a rack into
position. Much easier to perform in 0g than in 1g.

In that respect, the experience gained from the ISS is very valuable.

As far as multiple separate ships being launched to mars, than you are
essentially stating that you will perform assembly while in transit when those
ships meet, and/or perform the assembly in mars orbit. However, will you be
restricting astronauts to an apollo sized capsule for their 6 month trip ?

If we had the technology to put a man to sleep for 5 months and have him wake
up in great physical shape without any degradation to his bones and muscle
mass, then perhaps a single vehicle launched direct could do the trick. But
somehow, I really really doubt that you could have a single launch vehicle be
large enough to allow a crew to "live" for 6 months each way.

Consider the current ISS. Lets assume that in its current config, it would
have sufficient power to run ECLSS for 6 crew members and that it wouldn't be
consideredf too crowded for 6 people to live/exercise in for such durations.
(replace "research" racks with ECLSS and additional roomettes).

Could anything reasonably on the horizon have had the power to lift something
the size of the ISS in one shot ?

"Greg D. Moore \(Strider\)" wrote:
[...]
(on possible option is to aerobrake, dump a crew return vehicle and then
have the unmanned craft take its time through the belts. Hard on the
electronics, but easier on the passengers.

I was just wondering, right before I read this, about the mothership
using multi-pass aerobraking. Henry has pointed out, in discussion of
Apollo's reentry corridor IIRC, that it would take many passes to get
back to LEO, but hey, robots don't bored....

I wonder if any of the published papers consider this "valet parking"
scenario? I guess I just assumed in reading about CRV-like scenarios
that the mothership would be left in a solar orbit.

As to the radiation-vs-electronics issue, you're going to want your
ship to still be controllable after a solar storm, so you're going to
have enough electronics in the storm shelter for at least basic
command & control, and your RCS and main engines will be interfaced in
a robust way. You simply leverage that capability to have the valet
protected in the belts (acknowledging the difference in types of
radiation exposure), perhaps rearranging your remaining stores and
non-landing equipment to improve their contribution to the sheilding.

And, if I may be permitted to laugh at my own humor, I just had a
picture of the mothership popping a big solar sail brake as she
approached the "finish line", looking like a really long-railed Top
Fuel dragster....

/dps

"Barbara Needham" wrote in message
. ..
Renee Keller wrote:

Opened the door. But, I am curious here. Suppose all the above about
building in orbit actually worked and somewhere out there it was able to
be accomplished. What are you using for fuel, and how will the fuel in
sufficient quantities get to where you want it and be able to be
"loaded" or whatever the proper term is onto the correct spacecraft;
meanwhile waiting in the building facility to be utilized?

Important question, and I am glad you brought it up as I left that out.
Lets forget the possibility of manufacturing fuel in space for now since I
think we can all agree it is way down the pipe. Lets also assume the
technology or Nuclear engines just is not there yet and stick to the
conventional kind. The fuel would still have to be shipped to orbit, The
weight of that fuel would still be the same, BIG. But it would be minus the
weight of the structure to support the giant size craft to survive the
atmosphere, and would be minus the kind of engine to lift it to orbit. If
multiple trips are made, we are talking about lifting only more fuel and
supplies to the craft, as opposed to relifting the entire craft.

John Doe wrote:

Derek Lyons wrote:
Nor are the need to provide for them particularly onerous. The pumps
for those cranes that haul around city-block-sized chunks of aircraft
carrier
(http://www.nn.northropgrumman.com/ph.../C98-559-1.JPG)


The motor may not be onerous. But the structures needed to lift it are. Just
how are you going to send wuch a large crane structure to the moon surface ?
Will you need another crane to lift that crane up into position while a bunch
of astronauts climb onto to it to make the final welds ?

Attach a smaller crane to rails on the side of the larger crane under
construction. Attach an elevator to the other side of the crane under
construction. These problems are long solved for terrestrial
construction of sicilian structures.

Note that while it is true that working in 0g is not as efficient as working
in 1g, if more of the modules are outfitted on the ground and the work in 0g
is more of a plugging the modules together type, the inefficiencies of 0g are
much less.

It gets way more complicated when the modules get above the rather
modest size of current ISS modules.

Also, consider that some tasks are easier in 0g. Consider placing a rack into
position. Much easier to perform in 0g than in 1g.

Completely false. A fairly simple machine installs the racks into the
MPLM's.

D.
--
Touch-twice life. Eat. Drink. Laugh.

"Andrew Gray" wrote in message
. ..

Yeah, it's easier to shift big heavy things in freefall. But it's
massively harder to do simple technical work in freefall and in vacuum,
it's much more tiring on your workers, there's a lot of nasty
constraints that can be avoided by simply having a gravity well and a
nice hard floor to work on.

Strangely you just reminded me of something I did recently. I was hanging
about 20' down a pit on a rope trying to secure a beam across the pit. It's
amazing how being "in the air" with no ground under me made simple stuff
"hard". (Simply trying to pull a strap in one direction you really
understand Newton's laws. :-)



Admittedly, the Moon is not a great solution either; it still needs
pressure suits for external work, being essentially vacuum, you still
have a lot of the thermal problems (and some new ones), but... It's
misleading to pick one point and use that as an example. The enviroment
we can work in most efficiently is a warehouse on the surface here, but
that still doesn't make it optimal g

--
-Andrew Gray

"John Doe" wrote in message ...
"Greg D. Moore (Strider)" wrote:
I can't think of too many cities that were built for the sole purpose
supporting a single purpose.

Most mining towns in Canada and countries such as Australia and Russia are
single purpose towns often built by the mining company. And there have
been
many examples of towns litterally closing down when the mine shuts down.

Yes, there are exceptions. But note they are rare and in those rare cases
literally DO pay for themselves because of local resources.

And yes, ultimately I'm sure we'll have our mining towns on the Moon, but
only when the value of the exported materials is high enough (which means
cheaper than coming from the Earth.)


Also, if you look at Baikonour, isn't that a single purpose town ?

Good point.


Building an assembly plant on the moon is ludicrous. It will be far easier
to
assemble something in earth orbit since you don't need mega powerful
hydraulic
systems to move modules around as you would in a gravity environment.

Mega Powerful hydraulic systems?

Hell, give me a couple of 4x4 beams, some rope, and I can lift a several
hundred kilo load by myself.

It's old technology that's pretty simple.

John Doe wrote:
"Greg D. Moore (Strider)" wrote:
I can't think of too many cities that were built for the sole purpose
supporting a single purpose.

Most mining towns in Canada and countries such as Australia and Russia are
single purpose towns often built by the mining company. And there have been
many examples of towns litterally closing down when the mine shuts down.

Also, if you look at Baikonour, isn't that a single purpose town ?

No, Baikonour is not a single purpose town, its not even near anything
single-purpose. Tyuratam also pre-existed Baikonour though IIRC it wasn't
all that large and got remolded.

--
Sander

+++ Out of cheese error +++

"Greg D. Moore (Strider)" wrote in message
...

Granted, over time it may be cheaper (if you're launching 1 million craft
a
couple times a year from the Moon, you might find an advantage, but you
have
to do the math first.)

Right now orbital assembly with parts build right here on good old terra
firma is cheaper.

We are on the same page. It would most likely be cheeper to build and
launch from orbit if we had the infrastructure in place. And to justify the
cost of getting that in place we would have to have multiple launches planed
or at least in the works.