NASA SP-413 Space Settlements - Saint Ann's School

NASA SP-413 — SPACE SETTLEMENTS — A Design Study
47
TABLE 4-2 — Concluded
(b) Multiple components
Multiple dumbbells,
R = 236 m
R sphere = 33.3 m,
Multiple torus,
R maj = 209 m,
R min = 27 m
Banded torus,
R major = 209 m,
R min = 27 m
Number of components
Structural mass at 1/2 atm, kt
Projected area, m 2
Surface area, m 2
Shielding mass, Mt
Volume, m 3
Mass of atmosphere, kt
Segmentation
Vistas:
Longest line of sight, m
Solid angle of 50 percent
sight line, sr
Fraction of habitat
hidden from view
Communication:
Longest distance of
surface travel, m
Fraction viewable by
internal line of sight
from one place
Interior:
Openness
Volume/area, m
Population capacity at
35 m 2 /person
50
20
3.5 X 10 5
13.9 X 10 5
7.2
1.5 X 10 7
9.9
Unavoidable
67
4.2
0.99
540
0.01
Good
43
10,000
5
23.2
3.6 X 10 5
11.2 X 10 5
5.2
1.5 X 10 7
9.5
Unavoidable
100
0.9
0.93
720
0.07
Fair
42
10,000
1 (8 bands)
26
3.6 X 10 5
8.2 X 10 5
3.6
1.8 X 10 7
11.3
Easy
100
0.9
0.9
720
0.1
Poor
50
10,000
costs of converting raw alloys into structures by directly
using the vacuum and solar heat available in space. Its
simplest application lies in the fabrication of seamless
stressed-skin hulls for colony structures, but it appears
adaptable to the fabrication of hulls with extrusive window
areas and ribs, as well as to rigid sheet-like elements for
zero-gravity structures such as mirrors and solar panels.
A simple system might consist of a solar furnace providing
heat to an evaporation gun, which directs a conical
molecular beam at a balloon-like form. The form is rotated
under the beam to gradually build up metal plate of the
desired strength and thickness. While depositing aluminum,
the form must be held at roughly room temperature to
ensure the proper quality of the deposit.
Structures Inside the Habitat
To fulfill the criteria set forth in chapter 2, a light-weight,
modular building system must be developed to serve as an
enclosing means for the various spatial needs of the colony.
Modular building systems developed on Earth can be
categorized into three general types: that is, box systems
using room-size modules; bearing-panel systems; and
structural-frame systems. A box system entails assembling
either complete shells or fully completed packages with
integrated mechanical subsystems. Bearing-panel systems
use load-bearing wall elements with mechanical subsystems
installed during erection. Structural-frame systems use
modularized framing elements in combination with
nonload-bearing wall panels and mechanical subsystems
which are normally installed during erection. Other systems
which have seen limited application on Earth but would be
appropriate in the colony include: cable supported framing
systems with nonload-bearing fabric and panel space
dividers, and pneumatic air structures using aluminum foil
and fiberglass fabrics with rigid, aluminum floor elements.
In selecting a baseline configuration, box systems were
rejected because they normally involve the duplication of
walls and floors and tend to be overly heavy. If metal vapor
deposition is developed as a forming technique however, this
type of system would become highly desirable.
Bearing-panel systems were likewise rejected since they do
not allow integration of mechanical subsystems except
during erection, and since walls are heavy because they are
load bearing. Cable and pneumatic systems were rejected
due to their inability to span short distances without special
provisions. However, they might be highly desirable
because of their flexibility and lightness if a lower gravity
environment proves acceptable in the colony.
The system that appears most suitable for use in the colony
might involve a light, tubular structural frame (composed of
modular column and beams) in combination with walls that
Chapter 4 — Choosing Among Alternatives