devoted to space-based applications, with only the differences from the near-term market presented for Earth applications. Space Applications As transmission technologies improve and experience with beamed power grows, new markets will be opened up for commercial beamed power. From a business perspective, the main road block to commercial usage of beamed power in space is the conservative nature of the space industry. Lead times between development of a technology and the first real use of it can be extremely long, as few designers are willing to risk their spacecraft with unproven technologies. An excellent example of this comes from the electric propulsion field. The first space testing of ion engines, SERT 1 (Space Electric Rocket Test), was conducted in 1962 from a sounding rocket. Only now, 30 years after the first space tests were conducted are spacecraft being launched which use this technology, despite the large savings in propellant it can offer. Mid-term markets in space will appear when transmission technologies have been shown to be reliable enough so that spacecraft designers are willing to base their power system designs on receiving power rather than generating it themselves. Reaching this state of technology development will be quite a big step. To convince businesses and governments to risk their satellites on an outside power source, a fully tested, fully redundant system will have to be in place. This implies a constellation of satellites such that at least two power generating satellites would be in view of a client satellite at all times. The time frame for entering into this mid-term phase is highly dependent on the degree to which the near-term market is exploited. Optimistically, if the first application of power beaming for satellite lifetime extension occurs within the next decade and power transmission technologies are actively pursued, this mid-term market could conceivably begin to appear by about 2010. This is further complicated by the currently immature state of space laser technology. A more cautious estimate would predict this sort of market appearing by 2020 or 2030. So taking the “mid term” to be start 30 years from now, we need to try to predict the markets and technologies which will exist. There are several possible markets for beamed power in space: one could sell satellite lifetime extension; eclipse power for satellites or space stations, allowing a reduction in battery weight; baseload power for the same; or power for OTV's moving between LEO, GEO, and LLO using electric propulsion. Each of these potential markets has distinct advantages and disadvantages; trying to predict their relative weights for a market decades in the future is a difficult task. Satellites Extension of satellite lifetime was examined above as a possible near-term market, but did not appear to be a source of sufficient revenue to support a power satellite. For the mid-term, however, it may be a viable market, and could take on several different forms. Even though some satellites may be designed to be dependent on beamed power in this period, it is likely that most will continue to rely on their own power systems. With this in mind, and predicting a moderate increase in satellite cost in the next decade, one can make some guesses about the potential value of this market. Taking a satellite costing about $300 million with a 20 year life span which might be launched 10 years from now, each year of life extension would be worth about $15 million. If such a satellite's life could be extended for about 4 years, this would give a total value of about $60 million for extension of one satellite's life. Noting that maximum eclipse time in GEO is 1.2 hours/day, at most 20 satellites could be serviced using a single transmitter for a total value of $1.2 billion. Figure 3.1 below shows the results of a simulation run for Intelsat VI over the period around the vernal equinox. As can be seen from the graph, the dark time for the satellite drops off sharply at either end of the eclipse season. Average dark time is about 3.7% over the eclipse season, so that in the case of a constellation of satellites, duty cycles will allow each satellite to service about 27 satellites over the relevant period. Using this figure instead of the individual peak duty cycle yields a potential market worth of about $1.6 billion.
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