cells (and possibly other radiation-resistant cell types as well) may be able to stand up to this environment. FIGURE 1. Number of satellites required for a phone network to provide worldwide continuous coverage, as a function of altitude (data from Bailey and Landis [1]) Some further comments of note from the discussion of the workshop summary: Geoffrey Sommers said that telephone satellites will not have a lot of fancy electronics; they will be simple relays, and could be built so that the electronics will be (relatively) radiation tolerant. Thus, if the solar arrays could be made radiation tolerant, it would indeed be possible to utilize high-radiation orbits. Irving Weinberg said that radiation-tolerant cells such as InP are important for commercial applications in GEO, not just intermediate orbits. He said that a satellite in GEO accumulates a radiation dose of 1015 electrons over ten years, and that this results in degradation in power of 30 to 40 percent. Further, he notes that the next generation of commercial satellites are going to extended lifetimes of fifteen years and longer, making radiation-limited lifetime important. Finally, Lew Fraas concluded by reminding us that research aimed at near-term markets is a job for industry. The government should think in the long term, and fund technology development, so that we maintain a technology base for industry to draw on in the future. Conclusions Cost is the main issue for space photovoltaics, but cell cost is only a minor (10%) component of the cost. The parameter that is most desired out of next-generation
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