Proper management of space debris may solve this problem. For example, objects can be disposed of by putting them into orbits with an apogee less than the altitude of the construction orbit for the power station. Or, selected orbits can be reserved for SPS construction. (2) Entry Systems Entry systems are expected to raise two environmental issues: 1. sonic boom and 2. N0x production in the stratosphere. Both of these issues will require further investigation. The effects of sonic boom can be minimized by design factors, the location of the recovery site, and changes in the entry path. These considerations should influence the location of the recovery site, so that the sonic boom will occur over unpopulated areas. A significant amount of N0x is produced by the shock waves resulting from entry of a spacecraft into the Earth's atmosphere. However, this N0x is deposited at a sufficiently high altitude that the effect on ozone is reduced. Before an accurate evaluation can be made, more work is required. If air breathing engines are used to land the spacecraft, N0x will also be produced. The amount of N0x will be of the order of, or greater than, the amount deposited by a large passenger jet. However, since most of the fuel is expected to be burned in the troposphere, the net effect of these engines on ozone will probably be less than the passenger jet. (3) Power Transfer System The power transfer system consists of the SPS itself, the microwave beam, and the rectenna. Of these, the microwave beam is probably the most significant. a. Microwave Effects From previous studies, narrow limits have been imposed on the microwave frequencies and power densities to be used. For this reason, it becomes important to the SPS project to have a thorough understanding of the environmental effects of these microwaves. There are two areas which will require a major amount of work: (1) long and short term effects of microwaves on life. (2) global and local effects of ionospheric heating. 1. Biologic Effects The effects of microwaves on life may well be the most important environmental questions to be studied. Aside from an abnormal
RkJQdWJsaXNoZXIy MTU5NjU0Mg==