SMF Construction Process

> 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...

http://www.amazon.com/exec/obidos/tg/detail/-
/0446955590/qid33601044/sr=1-10/ref=sr_1_10/103-4733195-1790246?
v=glance

Heppenheimer (Colonies in Space) and O'Neill (The High Frontier)
both wrote excellent books on subject, both pack a lot of details in
but also write so that a dream is born.

> 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;

Sometimes I don't make myself clear in my writings. I need to work
on that. When I write Habitat I mean the kind of place with open
spaces, families living there, a BIG place. When I write about a
station, I mean the kind of place where you've got a room, you eat
your chow in the mess hall, you share the restroom. You're there to
work and you call your family on the phone if you get lonely.

Actually, I was talking about building a torroidal Station, not
Habitat, so I completely see how my not clearing up MY distinction
between Habitat and Station, could run afoul of othr people's
definitions.

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.

Well, it was your response that was the trigger to get me to finish
writing the huge "Bootstrapping in 60 Easy Steps" post I just upped.
If you can keep awake as you read through that, then you'll see I'm
not ignoring your concerns, or pretending like we don't need space
resources to build stuff in space. WE DO! But we also need worker
housing, and that the one little piece I was talking about in this
thread.

> 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.

No problem. I hope I've presented you with the largese and
complexity you crave in the "Bootstrapping" post :))))

> 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
> use.htm>
>
> and some other Google hits
>
le/External_Tank/>
>

I admire the thought these people have put into their proposals and
I too think that a use can be found for those Extrnal Tanks. Here
are some things to consider:

You can get the tanks for FREE. The National Commission on Space in
1986, Congress in 1987 and 1988, and President Reagan in 1988
directed NASA to make the ETs available to entrepreneurs. NASA
signed Memoranda of Understanding in 1987, 1989, 1992 to provide ETs
to the External Tanks Corporation (ETCO) of Boulder CO and Global
Outpost Inc. of Las Cruces, NM. But there are some strings attached.
You've got to take delivery in orbit with no extra work for NASA.
You have to stabilize their orbit so they don't come tumbling
uncontrollably into the atmosphere. NASA won't permit any
modifications to the tank prior to launch. That means no prebuilt
structures in the tank through which the fuel or oxidizer would flow.

So let's say, unlike the two companies above, you actually met all
of the conditions. That means you've got your own orbital
capability. So you can take the tanks off of NASA's hands. Now,
you've got to purge the thing and bring up all of your equipment and
workers to transform it while its in orbit. I've got one word for
you: EXPENSIVE. You've got to launch all of your gear and the
workers to install it. Working in zero-g is a lot less productive,
especially in a space suit, than working in an automated factory,
with cranes, robotic welders, jigs, every tool you could want within
reach, an equipment failure can be repaired by getting on the phone
(hey, do you think MAYTAG would send up their lonely repairman to
fix your broken dryer in orbit? :) All you're saving is the
cost of the pressure shell. I can't see it working out. What I can
see though is taking these ETs and using them as fuel storage tanks.
That makes sense to me. Or using them for their chopped metal value.
Or for some cheap open storage/warehouse space, light assembly. But
not as a space station. But hey, that's my opinion.

>
> 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.

Well, I'd venture a guess that the amount of fuel you'd expend in
matching orbits would more than outweight the value gained. Solar
panels degrade over time in space. Even new panels degrade by, IIRC,
>10% as they journey through the Van Allen Belts on their way to
GSO. The propellent is either Hydrogen peroxide, which degrades
about 1% a year. Or it's hydrazine or nitrogen tetroxide, both of
which are explosive. So you do run some risk in going to salvage old
fuel. How much risk? Couldn't tell you. I guess I'm left wondering
what you'd do with this salvage?

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!

I kind of touch on the housing issue in my bootstrapping post. To
address your question of knowing what you're going to go after
before you even launch. Yes, that sounds like good planning to me.
But I still can't get my head around, why do you want those spare
parts? How much expense are you going to incur in zipping around,
changing your delta-v to match all of those satellites' orbits and
doing your handiwork. And then somebody has to ctrack open that ET
and make it livable. As Al Globus pointed out to me, the complexity
of just the ISS radiator/truss section is pretty impressive. Having
thought about it, I have to agree that space is a harsh environment
and that translates into money. I think that same principle has to
be applied to the ET conversion proposal. All it is is a pressure
tank. To make it into a livable space for 1 to ,you name it, people
is not going to be cheap.

> 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).

Yeah, I agree with you.
>
> > 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.

Good point. That's what I'm trying to figure out. The pressurization
doesn't have to be a full 1 atm. Just enough not to damage the
components. And if they're not launched with the assembly, they've
got to be launched seperately. So the way I see it, we're just
delaying the cost to a future date and adding the expense of
integrating those components by having the astronaut do it.

You know the problem with forums like this is that we often know
more than we write in a post, so that what the reader gets is only a
partial picture. That's what I'm sensing from you. I'm reading that
you keep referring to the SPS making things easy. I'm sure you know
exactly what you're trying to say, but all I get is that somehow
there's a SPS in orbit and you've got lot's of power, but I have no
clue how you got that SPS up there I'm not getting the full
nature of your response.

Take a look at the Bootstrapping thread and tell me if you see
another way of getting from a to z. I tried to be comprehensive in
all of the steps that I could foresee. Then maybe we can reference
back to these concerns.

Right
> >now, I see those first facilities being earth manufactured and
then
> >additional capacity is added to them from lunar derived materials.

I agree with you wholeheartedly.

> >
> 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.

Well here's a point that we can each take a side on and investigate
and argue. We keep it on topic and see where it leads us.

>
> >>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.

Well, I'd have to crack open my Physics books and then figure out
what your numbers were referencing.

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.

You make a good case. Assuming the numbers compute properly, I would
definitely take my idea back to the drawing board.

Just as an aside, if people are breathing bottled air via a ace
mask, how low can the pressure in their environment go before its
unhealthy for them.

Maybe a solution is a very low pressure, enough to mitigate against
vacuum damage, enough to allow people to work in shirtsleeves, but
with their own air supply. Any thoughts?

> 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.

Here too, you raise some worthy points. You're right, there might
indeed be some benefits to an unpressurized bay.

> 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.

Well, if suit and envirnoment are all the same pressure then no
prebreathing is necessary. But coming back to earth is going to be a
problem, especially if you're the pilot.

> 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're mixing apples and oranges. I was writing about constructing a
station to house thousands of worker to perform the tasks of
refining, fabrication etc.

It appears to me that you're writing about the workers needed to
build the shack that will house the workers that build the SPS and
the big habitat.

I'm not far from your viewpoint. Again, look at my bootstrapping
post. There is a smaller housing station that initially is ued to
get the shack started in LEo, then it's moved to the moon, then it's
moved to L1.

>
> 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.

I'm not exactly sure what you meant by that closing remark. I'm
going to take a guess and venture a clarification, no offense
intended. The SMF in the title refers to Space Manufacturing
Facility, a prettier moniker for what started us as the Construction
Shack.

As for the Stanford study, I think they premised it a wide cross
section of the population so that NO ONE would sense discomfort from
the increased rpm. I contend that our initial workers will be chosen
for psychological stability in cramped quarters, higher rpm
environment, etc. Not just anybody's granny can go and be a elite
astronaut welder/fabricator/miner, etc.

Torus' can be smaller and rotate faster than the Stanford model,
it's just that now some people will experience discomfort, while
other won't. I saw a study where no one had discomfort a 1 rpm, only
a few at 2 rpm, a significant jump at 3 rpm, and everybody at 5 rpm.

> 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.

Sure, OK. I'm not proposing torus. I just happened to chose it as
the form factor because I had just run a whole slew of numbers on
it. Barbell works for me just as well.

>
> > 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?

That's a compare and contrast statement. It may damage the sensitive
stuff, but it won't damage the mundane stuff, but you still need to
haul both into orbit. That's all I was trying to say.