Kalpana One design (was Rotating space colonies)

Chris,
I'm neither an engineer nor a mathematician, so I'll just have to trust you on your figures. As to your scenario, though, I will comment. First, It still seems to me that you are putting the cart before the horse. At present we have One (1) damn flimsy space station (sans gravity of any sort) in orbit and One (1) experimental Bigelow habitat at half size. We have NO facilities on the moon, or elsewhere to provide living space for humans, let alone to provide materials for the construction of a large habitat. The first steps (and THAT is the primary imperative that MUST concern us if we are EVER going to establish a permanent presence in space), are to provide low cost access to space for men and materials and to provide facilities for those men (and women) to live and work in an environment that will allow them to retain their musculo-skeletal strength and health over the long term so that they can return to Earth if they so desire. Given the state of the worlds varied economies, NO-ONE is going to be investing hundreds of billions of dollars to construct a huge habitat right off. Therefore, we need to come up with a way to get workable habitats in space that don't call for that level of investment. Once we have large numbers of people living and working in space, and the nations see that it can be economically fruitful and that people are determined to settle there despite the apathy of governments, interest in further development will begin to grow.
In the beginning, though, we need to start simple and cheap. Suppose we place seven (7) shuttle external tanks in a stable orbit and arrange them in a rosette (six arrayed around a seventh placed in the center), weld them and cable them together to form a single cylindrical unit. Each tank has the dimensions 154'X27.6', which gives us an outer circumference of roughly 260' and a length of 154'. if we then install a flat deck in each of the tanks so that as the structure rotates it becomes the floor, we should end up with a usable area of about 40,000 sq' under 'gravity'. distance from the 'floor to the center of rotation would be in the neighborhood of 35-40', so one might experience some slight disorientation due to coriolis forces, frankly I'm not sure (but neither is anyone else), but chances are it could be gotten used to. SHIELDING, yes, the BIG problem. Again, I don't know what can be done about that, unless possibly a barrier could be built, between the sun and the structure, composed of materials brought up in bulk from Earth (concrete, H2O, pulverized rock, etc.), certainly one would think that we will have saved enough by utilizing available resources for the structure to finance a bit of shielding.
In any case, this is just a rough scenario, but you take my point. We have to start with what we HAVE and develop that as far as we possibly can to get an infrastructure in space that will be able to form the workforce that WILL work on the dedicated worldlets like Kalpana 1 and the O'neil habitats, and others that we can't even envision today. Without places like my little mock-up above, I fear that we may never get the people and resources into space that are necessary for us to begin the process of industrializing and colonizing our planetary space, let alone interplanetary spaces.
Victor

From: csmyth3025
Sent: Thursday, September 30, 2010 5:34 AM
To: spacesettlers@yahoogroups.com
Subject: [spacesettlers] Kalpana One design (was Re: Rotating space colonies)

Your point is well taken, Victor - but we need to distinguish between an
"orbiting space colony" and those facilities that will necessarily
precede its construction. I would put these predecessor facilities
(habitats, if you prefer) more into the category of construction shacks
or construction camps. These types of facilities will be needed, of
course - both on the Moon (the most likely source of raw and processed
construction materials) and in orbit (to effect the construction of the
station). The initial facilities on the Moon will likely develop into
lunar colonies in their own right - in much the same way that Boulder
City, Nevada has become a city with its own economic base despite its
purpose-built function as quarters for the workers (and in many cases,
their families) who were constructing the Hoover Dam (a 5-year project
that was in 1931-1936 located in an isolated and remote area).

I'm inclined to think that a 100-person orbiting space colony is about
as small a "village" as you could get. Anything smaller would most
likely be a corporate or government "purpose-built" facility. There will
no doubt be larger colonies built - such as Kalpana One - designed to
house 3000 people and more. In this respect, I agree that Kalpana One is
a 2nd or 3rd generation facility. A 100 person facility is a first
generation true orbiting space colony in my mind.

Constructing a Stanford Torus-type 100 person facility is a massive
undertaking. If one takes the 1977 Ames Research Center study for
shielding requirement for radiation workers (5 rem/yr) as a baseline
requirement (with shelters akin to "hurricane shelters" to weather
infrequent intense CME's from the Sun), the shell of the torus and, I
would think, the "spokes" as well, will have to be constructed with
about 2800 kg/m^2 "walls". As it turns out, this mass is equal to about
1 meter of "typical" concrete - which has a mass of about 2400 kg/m^3.
High density concrete is more than twice as dense as "typical concrete"
so a designed concrete shell one meter thick with a 3,000 kg/m^3 density
should be easily achievable. Likewise, glass for skylights (more likely,
lightwave guides) is about as dense as concrete (ranging from 2000
kg/m^3 to ~8000 kg/m^3). A one meter thick shell of reinforced concrete
and glass "skylights" seems a reasonable design point.

The amount of mass for this shell is tremendous. If one assumes that the
torus has, as I stated in my previous post, a radius at the main "deck"
of 223.4 meters and a "tube" diameter of 15 meters, the surface area
that must be covered is 66,146 m^2 [Area=(4*pi^2*a*r)+(4*pi^2*r^2),
where a=the inner radius of the torus and r=the radius of the torus
"tube"]. The mass of the shell of the torus alone comes in at a
staggering 198,438,178 kg.

If one assumes that the torus is connected to the central hub by three
15 meter diameter "spokes", the surface area of these spokes will be
30,522 m^2 [pi*15 m*215.9 m*3]. At 3000 kg/m^2 the mass of the spokes
adds another 91,566,430 kg.

By my calculation the mass of a 100 person Stanford Torus-type space
colony with three "spokes" adds up to about 290,004,600 kg. If we add
another 10,000,000 kg for the hub and miscellaneous structures that
brings the total up to about 300,000,000 kg, or about 300,000 metric
tons. This is a lot less than the 7 million metric tons for Kalpana One,
but it's still a huge amount of material.

I suspect that such a facility will probably be built by transporting
components (from the Moon, most likely) to the orbiting construction
site. In this regard I envision the components as sections similar to
the cylinder sections used to construct the English Channel tunnel.

Any comments on this scenario (or my calculations)?

Chris

--- In spacesettlers@yahoogroups.com, "Victor Smith"
>
...The stated mass requirements for the Kalpana 1 is 7 million tons
(including shielding). The authors of the plan therefore specefied that
the habitat must be assembled from materials derived from either the
moon or NEO asteroid harvesting, either of which is going to require a
whole infrastructure of its own. This is why I say that K-1 is, at best,
a second generation habitat, and probably 3g.