1) In the case of usage of visible laser beam for power transmission, there are three options for power density of the beam. • If there are any possibilities for animals (including human) to be irradiated directly by the beam, the beam power density should be less than 10'6 W/cm2 to protect their eyes against retinal injury. • If eye injury of animals (including human) can be neglected, and if the existence of humans in the receiver site is precisely controlled, laser beams up to 10"1 W/cm2 can be used. In this case, the local change of the ecological system should be considered. Depending on the consideration, total artificial sterilization of the receiver area may be required. • If the existence of any kind of living organism in the receiver site is forbidden, the beam power will be limited by environmental aspects other than biological issues. 2) In case of microwave beam usage, the following conditions are advised: • In the area where uncontrolled long term existence of animals including human is predicted, the microwave beam power density should be less than 0.5 mW/cm2 according to the ANSI standard. Other thermal and non-thermal effects shown in preceding sections. • Human entry to the area where the power density can be more than 1 mW/cm2 should be controlled • Animal entry, especially human entry, to the area where the power density is more than 10 mW/cm2 should be forbidden, except for monitored occupational persons. • The ecological system at the rectenna site should be monitored precisely. And if the new born ecological systems are harmful to other area, some countermeasures, including the total sterilization of the site, should be discussed and executed. • These electromagnetic effects are also the same for the workers on orbit. Even more, as they are irradiated by much more cosmic radiation than on the ground, more critical restrictions should be applied on the space workers. 3) For more detailed investigation about biological aspects of the beaming environmental effects, the following research and experiments are recommended. • Short and long term microwave exposure test on plants. It should be done both in the individual plant level and small ecological system level. We must gather the data about the microwave effects on plants at first because there are few reports on this subject as shown in above. This study will require two years for individual plants in short term and up to ten years for small model ecological systems. The latter should be continued also after the construction of the whole system to support the study of the biome in and around the rectenna site. • Prediction of the new ecological system which may be borne by the excess heat at the rectenna site and prediction of its effects. It will require one to two years to gather the existing ecological data and to make the prediction. • Basic experiments on the electromagnetic effects on living organisms and ecological systems using the frequency whose effects on biome have not been studied. For example, there is almost no research about the interrelation between the microwave of 35 GHz and living organisms. If we use 35 GHz for the power transmission, we must carry out all of the basic biological experiments described above in this section again in the new frequency. It will take only up to two years for such rather simple experiments, but other experiments, such as long time low power density exposure, will take more than ten years using small model biomes. They must be continued even after the construction of the whole system to predict the environmental and ecological evolution of the region in and around the rectenna. • Continuous epidemiological data collection on living organisms, especially human, in and around the rectenna site. This activity must be started before the starting of the beaming and must be continued as long as it works. Decades later after the construction, the data accumulated will tell us precisely about the effects of long term microwave exposure on the biome, biota, and individual living organisms.
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