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

NASA SP-413 — SPACE SETTLEMENTS — A Design Study
15
1934.
23. Wilcox, D.: The Voyage that Lasted Six Hundred
Years, Amazing Stories, Oct. 1940.
24. Heinlein, R. A.: Universe and Common Sense,
Astounding Science Fiction, May, Oct. 1941.
25. Shepherd, L. R.: Interstellar Flight, J. British
Interplanetary Soc., vol. 11, July 1952, pp. 149-167.
26. Clarke, A. C.: Electromagnetic Launching as a Major
Contributor to Space Flight, J. British Interplanetary
Soc., vol. 9, 1950, pp. 261-267.
27. Zwicky, F.: Morphological Astronomy, The Halley
Lecture for 1948, delivered at Oxford, May 2, 1948, The
Observatory, vol. 68, Aug. 1948, pp. 142-143.
28. Sagan, C.: The Planet Venus, Science, vol. 133, no.
3456, March 24, 1961, pp. 849-858.
29. Levitt, I. M., and Cole, D. M.: Exploring the Secrets of
Space: Astronautics for the Layman, Prentice Hall, Inc.,
1963, pp. 277-278.
30. Dyson, F. J.: Search for Artificial Stellar Sources of
Infrared Radiation, Science, vol. 131, June 3, 1960.
4 The remainder of the references for this chapter, i.e., 5 through 29, is as cited by Salkeld, R.; Space Colonization Now? Astronautics and
Aeronautics, vol. 13, no. 9, Sept. 1975, pp. 30-34.
⇔ 2 ⇔
Physical Properties of Space
The physical properties of space are rich in paradoxes.
Space seems empty but contains valuable resources of
energy and matter and dangerous fluxes of radiation. Space
seems featureless but has hills and valleys of gravitation.
Space is harsh and lifeless but offers opportunities for life
beyond those of Earth. In space, travel is sometimes easier
between places far apart than between places close together.
The purpose of this chapter is to explore and understand
these properties of space and the apparent paradoxes to
derive a set of basic design criteria for meeting the goals for
space colonization set out in chapter 1. Together with
considerations of the physiological and psychological needs
of humans in space, these basic criteria compose the
quantitative and qualitative standards on which the design of
the space colonization system is based. These criteria also
serve as the basis for a discussion and comparison of various
alternative ways to locate, organize and construct, and
interconnect the mines, factories, farms, homes, markets,
and businesses of a colony in space.
encircled gravitational valley. The more massive the body,
the deeper is this valley or well. The Earth’s well is 22 times
deeper than that of the Moon. Matter can be more easily
lifted into space from the Moon than from the Earth, and
this fact will be of considerable importance to colonists in
deciding from where to get their resources.
Libration Points: Shallow Gravity Wells
There are other shapings of space by gravity more subtle
than the deep wells surrounding each planetary object. For
example, in the space of the Earth-Moon system there are
shallow valleys around what are known as Lagrangian
libration points (refs. 1,2). There are five of these points as
shown in figure 2-1, and they arise from a balancing of the
gravitational attractions of the Earth and Moon with the
centrifugal force that an observer in the rotating coordinate
system of the Earth and Moon would feel. The principal
THE TOPOGRAPHY OF SPACE
For the resources of space to be tapped safely, conveniently
and with minimum drain on the productive capabilities of
the colonists and Earth, the peculiarities of the configuration
of space must be understood.
Planets and Moons: Deep Gravity Valleys
Gravitation gives a shape to apparently featureless space; it
produces hills and valleys as important to prospective settlers
in space as any shape of earthly terrain was to terrestrial
settlers. In terms of the work that must he done to escape
into space from its surface, each massive body, such as the
Earth and the Moon, sits at the bottom of a completely
Figure 2-1 — Earth-Moon libration points.
Chapter 2 — Physical Properties Of Space