The physical conditions and potentials of empty space are now familiar to us. Here is an idea of how our space station would have to be designed and equipped: In order to simplify as far as possible the work to be performed in outer space when constructing this observatory (this work only being possible in space suits), the entire structure including its equipment would have to be assembled first on Earth and tested for reliability. Furthermore, it would have to be constructed in such a manner that it could easily be disassembled into its components and if at all possible into individual, completely furnished "cells" that could be transported into outer space by means of space ships and reassembled there without difficulty. As much as possible, only lightweight metals should be used as materials in order to lower the cost of carrying them into outer space.
The completed, ready-to-use structure would, in general, look as follows: primarily, it must be completely sealed and airtight against empty space, thus permitting internally normal atmospheric conditions to be maintained by artificial means. In order to reduce the danger of escaping air, which would happen if a leak occurred (e.g., as a result of an impacting meteor), the space station would be partitioned in an appropriate manner into compartments familiar from ship building.
Since all rooms are connected with one another and are filled with air, movement is easily possible throughout the inside of the space station. Space travelers can, however, only reach the outside into empty space by means of so-called air locks. This equipment, (used in caissons, diving bells, etc.) familiar from underwater construction, consists primarily of a small chamber that has two doors sealed airtight, one of which leads to the inside of the station and the other to the outside (Figure 76).
Figure 76. Basic layout of an air lock for moving from an air- filled room (e.g., the inside of the space station) to empty space. Drawing the air out of the lock during "outgoing" occurs mostly by pumping the air into the station for reasons of economy; only the residual air in the lock is exhausted into empty space. [Editor's Note: This second sentence was a footnote].
Key: 1. Air outlet valve; 2. Air intake valve; 3. Outside door; 4. Outer space (airless); 5. Air lock; 6. Inside door; 7. Inside of the station (air-filled, pressure of 1 at absolute); 8. To air pump.
If for example, a space traveler wants to leave the space station ("outgoing" or egress), then, dressed in the space suit, he enters the lock through the inside door, the outside door being locked. Now the inside door is locked and the air in the lock is pumped out and finally exhausted, thus allowing the traveler to open the outer door and float out into the open. In order to reach the inside of the space station ("incoming" or ingress), the reverse procedure would have to be followed.
For operations and the necessary facilities of the space station, it is important to remember that absolutely nothing is available locally other than the radiation of the stars, primarily those of the sun; its rays, however, are available almost all the time and in unlimited quantity. Other substances particularly necessary for life, such as air and water, must be continually supplied from the Earth. This fact immediately leads to the following principle for the operation of the space station: exercise extreme thrift with all consumables, making abundant use instead of the energy available locally in substantial quantities in the sun's radiation for operating technical systems of all types, in particular those making it possible to recycle the spent consumables.