SMF Construction Process

victoriatangomanwrote:

>
>> Yow! This is the expensive way - I had thought that space
>>resources, by consensus, were the feed stock to run a SMF. As a
>>'hand-wave', I'll be able to accept this scenario (ignoring the
>>origin of the Stanford Torus sections)
>>
>No, I see I didn't make myself clear enough. I'm NOT saying build
>the Stanford Torus by earth launch.
>
>I'm talking about Heppenheimer's construction shack. Those first
>2,000 workers have to live somewhere. It could be the barbell with a
>sphere on top that Heppenheimer wrote about. I just chose to look
>into the "small" torus option.
>
Sorry I misunderstood you - could you please point me a site with more
info on T. A. Heppenheimer and/or Alan Driger? My google searches on
those terms have turned up overwhelming noise...

>>in order to address the "How do we assemble it" questions that follow; but I'd like to ask a few
>>questions of my own as well. Does this scenario assume an SPS already exists?
>>
>No, this is the first effort to build up the infrastructure. The
>housing, the refinery, the fabrication faciliteis, etc.
>
>>If so, what was it built out of, and how? If not, should an SPS be
>>built
>>as a companion to a SMF to provide power and shading?
>>
>Yes, it should. In the future I'll start another thread where we can
>discuss the minutae of bootstrapping up to a completed SMF, housing,
>lunar facilities, etc.
>
>>What sort of resources will an SMF be built from, and how?
>>
>Earth launched because at the moment there are no lunar or orbital
>resources to use, nor means to refine them, nor means to fabricate
>anything. I'm premising this thread on that first step into orbit.
>
Again, I misunderstood; but - you aren't talking about building a
toroidal habitat, but housing and minimal essential services to support
a minimum number of workers; you also don't seem to be talking about a
prospecting facility (turning space resources into raw materials, eg
asteroids into steel ingots and girders) or a general space
manufacturing facility (with heavy hydraulic presses, industrial cutting
tools, lathes, variety of welding capabilities to suit a wide range of
general manufacturing tasks) but instead an enclosed, controlled
environment where workers can use specific specialized tools to
accomplish only the single task of assembling a pre-fab facility.
Needless to say, the facilities I thought you were talking about are
much larger and more complex than the ones you are actually proposing,
and I didn't realize that I had constructed a strawman. Sorry.
On the whole 'Launch what you use, use what you launch' side of things -
what would you think of using pre-manufactured parts (already on orbit)
to convert Shuttle External Fuel Tanks into the initial construction
shack? I realize that you envision building the construction shack
components here on Terra, as dedicated purpose-built units, but it seems
an awful waste to ignore the ETs which we know will stand up to 1G, can
hold greater than 1 Atmosphere worth of internal pressure, already have
a small amount of insulation pre-built on, and are practically delivered
to orbit for free. There have been several seemingly sound proposals to
build 'Barbell' stations with ETs - could one of those proposals be made
to suit the needs of a mere construction shack? Check out these links:

PERMANENT

Space Islands

SIG - Geode concept

Orbit 6

Space Frontier

and some other Google hits

Aside from all the ET stuff, what about salvaging the existing junk
satellites? They have solar panels, radiation shielding, pumps, perhaps
a little propellant, batteries, various bits of electronics in several
states of repair, and all sorts of other supplies which might be just
fine, but without fuel, or an antenna, or a functional gyro, had to be
written off. I know, not the sort of top-shelf components you would
choose to buy if you had a zillion dollars to spend - but they all work
(or did once) and a precise inventory of what is available can be drawn
up before you ever launch a single gram, not to mention that moving
stuff around in orbit is LOTS cheaper than flinging it into orbit in the
first place. Maybe you would have to buy a launch n the cheap (or two) -
say a Sea-launch or Proton - to carry up essentials. Heck, I'm even
envisioning pre-fab circuit boards, minus the electronics, that hardware
from existing satellites is simply plugged into to provide basic
essential functionality. Also, it is entirely possible that just one or
two ETs could be made to serve as a functional construction shack,
suitable for housing the workers for building the rest of the
construction shack!

>>>If this is done, then how much will we have to worry about vacuum
>>>exposure in the open sections damaging all of the equipment.
>>>
>> Actually, I had always envisioned the construction of the
>>Torus being completed before moving any of the smaller equipment (and
>>certainly furniture!) into it. This means that the equipment
>>could always be kept in a controlled (or at least pressurized)
>>environment. The larger pieces of equipment - which have to be built into the
>>Torus as it is initially constructed - will be made of hardier stuff,
>>and not suseptible to vacuum damage.
>>
>Yes, I see your point. I used to hold it myself, until I started
>thinking about how expensive it is to keep an astronaut in space.
>
Once you have any portion of a functional shack built, the costs of
keeping someone in space should drop dramatically - the most insanely
expensive portion of this initial orbital construction is going to be
launch costs. If your shack can provide even a half or three quarters G,
basic air (not simply scrubbing) and water recycling, then the battle is
half won. Granted that you will have to launch food, but that is
something you would have to have done anyway, and perhaps the workers
could be encouraged to examine the feasiblity of an on orbit garden
(heck, it might be essential anyway - in the form of CELSS).

> I
>don't think it'll be cost efficient to have the astronaut running
>systems checks on all of the equipment, checking for bad wiring,
>installing lightbulbs, moving in stoves, refrigerators, dishwashers,
>computer screens, circuit breakers, etc. . . you get the picture.
>Better to have that done by cheaper labor on earth.
>
How much would it cost to secure all of those lightbulbs, stoves,
computer screens, refridgerators, etc in place well enough to survive
launch? And how much launch cost to you pay to up-port all that packing
material? And if you are worried about vacuum damage to even a single
component, you have to provide full life support (at least air pressure,
humidity, and temperature control) to the whole volume of the entire
section from the moment it is launched to the time when it is fully
installed and ready for your workers to move in. Not too much of a
problem if you already have an SPS, but it does seem kinda wasteful.

>I got to thinking about this problem and thought that a pressurized
>assembly bay would do it better. As a bonus, the assembly bay can be
>attached to the station and be used for construction of orbital
>transfer vehicles, deep space probes, etc.
>
[Snip]

>>>Should then, one of the first built structures in orbit be a
>>>large pressurized assembly bay (assembled piecemeal in a painstakingly
>>>slow process to allow for the large open volume required) where
>>>the quarter sections are assembled, the ends sealed, moved out of the
>>>bay and joined to other completed sections.
>>>
>> Here we are at the SMF again - should we build one, how, from
>>what, and what should it do? If we have one, how much do we really need
>>to launch? Where will the workers live? Myself I favor building a
>>SMF early on, but not first.
>>
>In my mind, the SMF and worker housing go hand in hand. I can't see
>how you have one without the other. Perhaps you can lay out your
>vision in more detail so that I can see how this can happen. Right
>now, I see those first facilities being earth manufactured and then
>additional capacity is added to them from lunar derived materials.
>
I understand now that you were envisioning just an assembly bay, and not
a real generalized SMF; it should actually be trivially easy to build -
though I am still unsure about the wisdom of pressurizing it.

>>Given an orbital assembly bay, should we bother pressurizing it? If you are building something
>>really big, and have to open the assembly bay up to let it out at the
>>end, how much atmosphere do you lose?
>>
>Depends on how efficient your vacuum pumps are.
>
Yes, AND the volume to be emptied. If the assembly bay has a large
enough volume, then even lowering the pressure to a bar or two will
still bleed off a lot of volatiles you paid to launch. Assume an
assembly bay, spherical, and about 101 meters in diameter, giving a
volume of 4.4 *10^6 cubic meters working space. Imagine that you keep
the facility pressurized to .5 Atmospheres, and heated to 0 Centigrade.
4.4 EE6 cubic meters is 4.4 EE9 liters of air, or 2.2 EE9 liters at STP
(Standard Temperature and Pressure); if memory serves this works out to
1 EE9 or 1,000,000,000 moles of air - I thinks this works out to ( .7 *
28 g/m + .29 * 32 g/m + .01 * 18 g/m = 19.6g + 9.28g + .18g = 29.06
grams per mole * 1000000000 moles * .001 kilograms per gram =) 29.06 EE6
kilograms of atmosphere. Please check that.. it does seem a bit high to
me. Assuming it is correct, and we can pay to launch all that (Yipe!),
and that your vacuum pumps can drop the interior of the assembly bay
down to .0005 atmospheres of pressure before openning up to let the
single (of many) finished section leave the bay; you still end up losing
about 29060 Kg of air. Even a bay only about 47 meters in radius (and
one tenth the volume) still loses 2906 Kg (two tonnes?) every times it
cycles open. The workers can bloody well wear pressure suits.

> After you've
>finished constructing your item, you depressureize the bay, open the
>doors, send it out, bring in the new components, close the doors,
>repressurize.
>
>What happens with convection in the bay -
>
>>will the welding create areas of superheated air which would be
>>invisible hazards to the workers?
>>
>There will have to be superb air flow througout the bay so that
>gases are dispersed. That's why I don't think the bay can just be
>a "dumb chamber" a hollow shell. It'll need to be a finely
>controlled environment.
>
>What about frostbite - if the bay is
>
>>sheilded, enclosed, and opaque, will it be unbearably cold once
>>you add an atmosphere to convect away the ambient heat?
>>
>Well, it's not a dumb chamber. It'll have environmental controls.
>
>>How will workers get around this huge volume, now that air restistance is a factor?
>>
>I envision ropes - one end tied to the bay wall, the other to the
>structure being assembled. Now you have zero-g freedom of movement
>about the structure, can use ropes for stabilizing the structure,
>and for controlling your own motion.
>
>>If we do not pressurize the assembly bay, what advantages does it have over
>>open space, and how do we maximize those advantages?
>>
>Can't really see why there would be an assembly bay that wasn't
>pressurized. In that case, don't build a bay.
>
Don't be too quick to dismiss an unpressurized bay - it still provides
sheilding from space debris, galactic and solar radiation, provides even
lighting and heating, and perhaps even energy and anchoring benefits or
psychological support for the workers who no longer have to work over
the bottomless void. This means the workers suits only have to provide
pressure and breathable air - all of the bulky sheilding and temperature
control systems can be left off. Maybe an unpressurized bay can work. Oh
yeah - it also simplifies the process of searching for any possible
leaks in the hull of whatever you are assembling.

>With a bay, workers don't need to suit up, pre-breathe, limit their
>time in space suit, can work without bulk of suit, have more ready
>access to tools that they're familiar with and all of the sensitive
>equipment in the station sections that are being asembled are
>protected.
>
Would a space worker necessarily have to pre-breathe? Presumably, all of
the air mix will be the same for ease of life support, and with lower
than 1 atmosphere of pressure is the bends really a signifigant problem?
The suits could even be a similar pressure to the atmosphere in the
living quarters.

>>>I'm just trying to imagine the asembly of a large facility for
>>>thousands of initial workers and how we would step through that
>>>process. Feel free to bring up your concerns and add to the ones
>>>I've raised.
>>>
>> I am unconvinced that we will initially need thousands of workers;
>>
>That's a whole other thread :) I'm just using Heppenheimer's figure
>of 2,000+ workers in the construction shack scenario. And to me it
>rings true considering how many specialized tasks there'll be in the
>refining, fabrication, as well as facility and equipment maintenance.
>
But the initial work will essentially just be welding together
pre-fabbed pieces, no refining, no fabrication, and minimal maintenance
considering that most systems shouldn't take much wear and tear until
they are installed and activated; and those that are used will be
stressed by fewer workers until the refining and fabrication operations
start up.

>>we may have to lift some fairly big and heavy equipment initially,
>>but dozens (perhaps a few hundred) workers should be able to handle
>>the building of the first, simple facilities. Even with thousands of
>>workers, I am unconvinced that a Stanford Torus will be the first
>>habitat.
>>
>I'm NOT writing about the Stanford Torus. The thread is entitled SMF
>Construction process, and I never once wrote Stanford Torus :) You
>can have a torus smaller than the Stanford study model.
>
True - but I thought the radius of the Stanford Torus was carefully
chosen for minimal size given engineering and psycological
considerations; and despite the title of the thread we have ended up
talking about the construction shack.

>Check out a graphic called "Torus sections" in the files section.
>
>>A simple 'Barbell' habitat seems much more likely to me,
>>
>> probably with a hub at the center of the bar for docking and
>>adding on of additional habitat sections. It has its own problems; but
>>built as a temporary lodging alongside of the essential initial orbital
>>facilities it could work well enough.
>>
>Yes, that's what I'm saying as well. A barbell station will also run
>into most of the concerns I've raised in this thread.
>
I think assembly of a barbell could involve considerably less welding,
and perhaps it would be suitable for housing a small (and expanding)
number of workers even while it is under construction.

> Barbell, samll
>torus, small sphere, samll cylinder - it doesn't matter to me. It
>needs to be built, it needs to come from earth, it needs to be
>assembled in orbit, it'll have lots of sensitive equipment in it
>that vacuum may damage. It'll have lot's on mundane stuff like
>chairs, pillows, pots, pans, forks,
>
How will vacuum damage these items?

> lightbulbs as well.
>
Ok, I'll concede that one.

> Any station
>will have to house and support the workers, whether we're using your
>figure of a hundred people, or Heppenheimer's (more accurately -
>Alan Drigger of the Southern Research Institute who based his work
>on earlier space station studies) 2,232 people.
>
>Either way, that's a whole bunch more than 3 guys up in the ISS.
>
All too true - the ISS is a disastrous white elephant of pork-barrel
political spending on so many disappointing levels. The poor bastards
couldn't even match the habitablity of the pathetically forsaken and
politically betrayed SkyLab. (*Idiots, I live in a country run by idiots*)

>> Sorry - I seem to have added more concerns and questions than
>>answers... I hope that some of this will help, and/or get the
>>creative juices flowing.
>>
>I enjoyed your response.
>
Misguided though much of it was. And thank you; I also enjoy this sort
of mental exercise.