IV.l: LOCATION 4.1 CHAPTER IV ASSUMPTIONS This study's space colony is in orbit around LS, the trailing Lagrangian point in the Earth-Moon system. LS is the vertex of an equilateral triangle in the plane of the Moon's orbit whose other two vertices are the Earth and Moon (see Figure 4.1). Thus, LS revolves with the Moon around the Earth. The advantage to this colony location is that certain orbits around LS are stable and periodic (4.1). Thus, the colony does not require station-keeping propellant for orbital corrections. Because no large thrusts are applied to the structure, the design is simplified. The only planetary bodies which can shadow a colony in orbit around LS are the Earth and Moon. Therefore, the location benefits from nearly continuous sunlight with occasional eclipses. The radiation environment is that of free space; LS is not protected by Earth's magnetosphere. The velocity requirements between various locations are shown in Figure 4.2. While the velocity increment from the Earth surface to LS is 13,000 meters/sec, the increment from the lunar surface to LS is only 2,4S0 meters/sec because of the Moon's lower gravity. This leads to transportation savings, provided we make a second assumption. IV.2: MATERIALS AND TRANSPORTATION To take advantage of the lower lunar gravity, the bulk of the materials for this study's space colony comes from the Moon. The lunar soil, a source of silicon, oxygen, aluminum, and iron,is packaged into 10 kilogram chunks and catapulted by a Transport Linear Accelerator (TL.'\) up to lunar escape velocity. These masses are caught at L2 (see Figure 4.1) and transported to the colony ~\ .... " ...........
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