TABLE 1 ESTIMATE OF POWER AND WEIGHT FOR PROCESSING EQUIPMENT course, as it cannot stand strong acceleration, it will be folded during launch and assembled on orbit. As the space factory will be constructed on sun-synchronous orbit, equipment must be designed to be lightweight. The next point we have to consider is to reduce power consumption. As a space factory requires a large amount of power, high electrically efficient equipment must be designed. This is important from the standpoint of heat rejection, too. As far as the measurement apparatus is concerned, commercial ones should be used as much as possible, though it may be heavy and consume more power, and they must be installed in as similar an environment as on the ground. In addition, a function of fault tolerance will have to be added for the measurement equipment. Progress in processing equipment is so rapid that they will have to be replaced with new ones. They must be changed easily. Table 1 shows an estimate of power and weight for dedicated processing equipment which is one fifth lighter than conventional ground equipment. RESEARCH DIRECTIONS TOWARD SSPF The items to be studied on a space station or a shuttle cargo bay before realizing an SSPF are as follows: 1. Demonstration of Direct Large Scale Wafer Production Our interest is placed on large scales and thin wafers. It is not so easy to slice an ingot on a space factory with high efficiency. Therefore, direct wafer production in space is quite important. On this point, direct wafer production for solar cells has been already tried on the ground, but the fabricating technique was not applied for IC-level wafer production. 2. Examination of Dynamic Behavior of Dust in Zero-Gravity Field Although the dust will not pile up on a wafer in space, detailed behavior must be manifested with comprehensive understanding of the role of gravity.
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