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Made in Space
This label "Made in Space" for industrial materials will probably surprise no one in the not so distant future. They may include superconductors, new kinds of alloys, substances with peculiar magnetic properties,supertransparent laser glass , polymers, plastics, and so on. Numerous experiments carried out at the Russian orbital space stations have paved the way to the development of methods and means3of industrial production of new materials of better quality on board a spacecraft. Experts estimate that within a few coming years industrial production of various materials will be started in space.
Conditions on board a space vehicle orbiting the Earth greatly differ from those on its surface. However all of these conditions can be simulated on Earth, except for one - prolonged weightlessness. Weightlessness can be created on Earth, but only for a few seconds. A space flight is another matter: a satellite orbiting the Earth is^n a dynamic zero-gravity state, i.e., when gravity is cancelled out by inertia.
What can weightlessness be used for? Many well-known processes go on differently due to the absence of weight. The Archimedes principle is no longer valid and, consequently, stable-state liquid mixtures can be obtained, the components of which would immediately separate on Earth because of different density. In case of melts of metals, glasses or semiconductors, they can be cooled down to the solidification point even in space and then brought back to Earth. Such materials will possess quite unusual qualities.
In space there is no gravitational convection , i.e., movements of gases or liquids caused by difference of temperatures. It is well-known that various defects in semiconductors occur because of convection. Biochemists also have to deal with the worst aspects of convection, for example, in the production of superpure biologically active substances. Convection makes it very difficult on Earth.
Following the launch of the first orbital stations the specialists started experiments aimed at proving the advantages of the zero-gravity state for the production of certain materials. In this country all orbital stations from Salyut 5 onwards were used for that purpose, as well as rockets. Since 1976 over 600 technological experiments have been carried out on board manned and unmanned space vehicles.
The experiments proved that many of the properties of the materials obtained under the zero-gravity condition were much better than those produced on Earth. Besides, it has been established that it is necessary to develop a new science - physics of the weightless state - which forms the theoretical basis for space industry and space materials study. This science has basically been developed.The methods of mathematical modelling of the hydromechanical process under the zero-gravity condition have been created with the help of computers.
Special space vehicles will also be needed for industrial production of new-generation materials. Research has shown that the acceleration rate on board these vehicles must be reduced to the minimum. It was found that space platforms in independent flight carrying the equipment were most suitable for producing materials. These vehicles will have to use their own propulsion systems to approach their base orbital station after a certain period of time. The cosmonauts on board the station can replace the specimens. Many new and very interesting projects are planned for orbital stations. Here is one of them. Convection does not allow to grow large protein crystals on Earth. But it is possible to grow such crystals under the zero-gravity condition and to study their structure. The data obtained during the experiments can be useful for the work of laboratories on Earth in using the methods of gene engineering . Thus, it may be possible to make new materials in space and also to obtain valuable scientific data for new highly efficient technologies on Earth.
Preparatory work for industrial production in space at a larger scale is being carried out in Russia, the USA, Western Europe and Japan. It should be said that according to the estimates of American experts production of materials in space is to bring 60-billion dollars by the year 2000.