of the spherical habitat with normal atmospheric pressure and separate shielding is 1.53 x 107 t and the shielding mass is 8.02 x 107 t [57] a ratio of and the increase of the shielding thickness from 2.04 m to 10 m is also about a factor of 5, it will be assumed that this increases structural mass by an additional 60%. The structural mass of the spherical, and thus of the cylindrical, habitat, with normal atmospheric pressure and shielding 10 m thick is therefore 1.6 • 2.56xl07 t = 4.10xl07 t. The shielding mass is and total habitat mass 4.34x10$ t. Because of the difference in shape between spherical and cylindrical habitats, there may be an approximate equality between the shielding masses of the spherical and cylindrical habitats. 8. The cylindrical habitat discussed above has radius 894.26 m, hemispherical ends, and length of 709.42 m of cylinder between the beginnings of the hemispherical ends, with minimum gravity 0.7 g, and gravity 1 g at the perimeter of the cylinder [58]. The largest proposed habitat will be discussed here, and additional scaling laws will be used to find its mass from the cylindrical habitat discussed above. This habitat is also a cylinder, with diameter 6.4 km and length 32 km. This maximum size is the structural limit, but I do not know how much shielding was assumed for the determination of this limit, and the structural limit with the shielding mass used here may be smaller. 9. The structural mass of a cylindrical habitat will be assumed to vary about as the radius, since the mass of a cylindrical shell of constant thickness varies as the radius, and load per unit mass from centrifugal force at the shell is constant because the gravitational acceleration is 1 g, independent of radius. 10. Since no additional load per unit mass is caused by extending the length of the cylinder, the mass will be assumed to vary as the length. Structural, Shielding, and Atmospheric Masses The factor for scaling the mass of the habitat which depends on length is and the radial scaling factor is The masses of both shielding and structure therefore are 45.1 • 1.79 = 80.7 times greater than those of the habitat of 10$ person capacity with design from SP-428 which was used above. The structural mass of the largest habitat is therefore 80.7 • 4.10xl07 t
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