A Giant Floating Mirror

The potentials of a space station are by no means exhausted with the above descriptions. Based on the condition that for the space station the sun shines unattenuatedly and continuously (disregarding occasional brief passes through the Earth's shadow), benefits could be derived, furthermore, for some technical applications on Earth. From the space station, the sun's radiation even on a large scale could be artificially focused on various regions of the Earth's surface if, as Oberth suggests, giant mirrors were erected that were appropriately built, orbited the Earth in a free orbital path, and hence were suspended above it.

According to Oberth, these mirrors would consist of individual segments, moveable in such a manner that any arbitrary orientation in the plane of the mirror can be remotely assigned to them through electrical signals. By appropriately adjusting the segments, it would then be possible, depending on the need, to spread the entire solar energy reflected by the mirror over wide regions of the Earth's surface or to concentrate it on single points, or finally to radiate it out into space if not being used.

"Space mirrors" of this type would be in a weightless state as a result of their orbital motion; this fact would considerably simplify their manufacture. According to Oberth, a circular network of wires could serve as a frame for their construction and, to this end, could be extended in space through rotation. The individual segments would be attached to the wire mesh and would consist of paper-thin sodium foils. According to Oberth's plans, a mirror of this type with a diameter of 100 km would cost around 3 billion marks and require approximately 15 years for its completion.

Besides this proposal, there would, no doubt, be still other possibilities of constructing a large floating mirror of this type. At smaller diameters of perhaps only several 100 meters, we could certainly succeed in giving the entire mirror such a rigid structure that it could be rotated at will around its center of mass, even in its entirety, by means of control motors, and that arbitrary positional changes could be performed with it.

The electrical energy necessary for controlling mirrors of this type would be available in the space station in sufficient quantity. The actual controls would have to be placed in the observatory and positioned in such a fashion that they could be operated at the same time while performing observations with the giant telescope, making it possible to adjust the mirrors' field of light precisely on the Earth.

The uses of this system would be numerous. Thus, important harbors or airports, large train stations, even entire cities, etc. could be illuminated during the night with natural sunlight, cloud cover permitting. Imagine the amount of coal saved if, for example, Berlin and other cosmopolitan centers were supplied with light in this fashion!

Using very large space mirrors, it would also be possible, according to Oberth, to make wide areas in the North inhabitable through artificial solar radiation, to keep the sea lanes to Northern Siberian harbors, to Spitzbergen, etc. free of ice, or to influence even the weather by preventing sudden drops in temperature and pressure, frosts, hail storms, and to provide many other benefits.

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