Specific Areas of Scientific Interest There are many areas in which ISPO needs to be in direct contact with the scientific community, and each must be considered in the light of its unique character. Quite apart from experiments required for feasibility studies of the program itself, there will be a large amount of power available in space for carrying out other experiments during periods when the satellites are not beaming or receiving power. Atmospheric Physics Scientists have major concerns in relation to atmospheric physics, particularly the possibility of significant heating of the ionosphere from microwave beaming. As these problems are one of the major technical obstacles to successful large scale solar power beaming projects, ISPO must work closely with scientists in this field. It would be relatively simple to incorporate experiments on board any power beaming tests. In addition to large-scale tests on the ionosphere, local plasma tests should be done, as the characteristics of this medium will affect the performance of the satellite. Compositional analysis of the different layers of the atmosphere could be carried out also. Effects on Biota For many years now experiments have been carried out on the effect of irradiating biota [Murakami, 1982]. Unfortunately, many of their results, while suggesting that relatively low microwave intensities have no major effects, are inconclusive and much more work is necessary in this field to prove the safety of long-term exposure to radiation. This work would be difficult within the context of ISPO, as it is not directly related to most of the other technical issues and IPSO's objectivity would be in doubt. However it is critical that this work is done and supported by ISPO as these effects are among the main concerns of the public. Effects on Electronics Experiments have shown [Osepchuk, 1986] that the effects of electromagnetic waves are much stronger on electronics than on biota, typically by 2-3 orders of magnitude. Thus if power is going to be beamed to Earth it is critical either that this is shown not to harm computers or other electronic equipment or that economical counter measures be developed. As this effect is strongly dependent on the thickness and separation of wires in electronic components, there may be strong opposition from manufacturers interested in continually reducing their size. Experiments in this area must be carried out by ISPO. Interference with Communications and Astronomy All areas of the radio spectrum are heavily used, and it is critical that any power-beaming equipment be very tightly characterized throughout its lifetime, to ensure that interference problems can be overcome or prevented. The precise frequencies suggested for use by space power systems are already used by communications equipment worldwide and radio astronomers have very strong objections to any heavy power applications throughout the microwave range, because of the high noise levels associated with industrial-scale use of electromagnetic radiation. Already domestic microwave ovens are a serious problem for observations [Osepchuk, 1991 ][Anderson, 1979]. Particularly in the area of frequency allocation, these scientists have a very strong influence. This necessitates cooperation where possible. Many manufacturers of communications equipment also work in fields associated with space power, making this easier. Negotiations with astronomers will be much more difficult, however, and must be initiated as early as possible. Solar Physics Solar Physics is of interest to space power systems for a number of reasons, as the use of improved solar models could affect the performance of any solar power satellite. The environment in which the satellites will travel is strongly dependent on solar activity, both in terms of occasional bursts of high energy particles and continuous particle and radiation fluxes from the sun. In addition the power collected by the solar cells will be strongly dependent on the optical and near IR output of the sun, and so improved knowledge in this area would be useful. Experiments to monitor solar activity are light, relatively inexpensive and do not require extremely stable environments. For these reasons they ought to be carried by space power satellites.
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