# What was being manufactured on Salyut and Mir?

Last weekend I attended a prelection at Polish Aviation Museum, on modern trends in aviation. The lecturer talked quite a bit of history too, and Soviet achievements were in as much focus as the western ones. Among all, he talked about missile guidance systems, including infrared homing.

He mentioned that materials for the superior (for its time) homing systems of air-to-air missiles were produced in a small furnace on board of Salyut, and later MIR space stations, as the manufacturing would be impossible in standard gravity; about 0.5kg of the material manufactured over a month of operation of the furnace would allow manufacturing of about 500 missiles with the superior guidance system.

Could someone provide more information - what substance exactly was being manufactured, and what about the process was so subtle that it required freefall conditions?

• There may be various inaccuracies in the question - I'm recalling the facts and figures from memory of what was a short mention during almost 4 hours of prelection, so I might have remembered some things wrong.
– SF.
Nov 24 '15 at 8:11
• Possibly a germanium compound such as en.wikipedia.org/wiki/Germanium_selenide. The infra red properties of some germanium compounds probably made them useful as filters so only infra red light was getting through to the detector..?
– Andy
Nov 24 '15 at 10:38
• There are some papers (for example - abstract only - adsabs.harvard.edu/abs/1992ssfu.conf..187R ) indicating not just optical materials, but also things like semiconductors were investigated. I still think it would be infra-red filters specifically for the homing systems though.
– Andy
Nov 24 '15 at 10:47
• One possibility would be large single crystals. These are definitely easier to make in microgravity. Could be the substrate for the IR detector. I haven't found references though (and as this was for military use, chances are there won't be any in open literature). Nov 24 '15 at 13:32

The Kristall (crystal) module of Mir carried a number of payloads for carrying out metallurgy and crystal growth experiments and was dubbed a factory in Soviet Press, as it was supposed to manufacture semiconductor samples for Soviet industries. The instruments abroad Kristall included,

• Krater-V electrical furnace- for producing perfect gallium arsenide and zinc oxide crystals of under microgravity conditions (~ $10^{-3}$ - $10^{-5}$ g).

• Optizon furnace- for semi-industrial production of perfect cremnium monocrystals.

• Zona-02 and Zona-03 furnaces- for semiconductor production experiments.

There are no reports of the actual production figures or even if anything commercial (beyond experiments) was produced.

• I guess applications of these in military systems goes far beyond the scope of the site and would be unlikely to be available to the public anyway, so I we can only guess it could be one of these.
– SF.
Nov 25 '15 at 8:03

I have a (probably exhaustive) list of every smelting experiments that where done on the space stations (Sayult 5-7; mir) I could post it but it would take time to compile (There was many experiments from different countries; including USA, Cuba, and Europeans).

Many of them where simple alloys. The idea was to study the whole process. Some of the experiments where filmed.

Eventually to obtain greater homogeny that could be obtained on earth.

Many crystals and semiconductor crystals where also processed; both bigger and purer than that we could do on earth.

The astronauts moving inside the station significantly worsened the results. Some experiments where done at night and during vacancy times to avoid this issue.

• This, unlike all the experiments. was actual production - its goal was not research, testing new ideas - but continuous production of a substance already developed. It's interesting as a case of application of microgravity conditions for actual, practical industrial purpose - a part of an ongoing manufacturing process providing components for physical products leaving the assembly line.
– SF.
Nov 2 '16 at 15:47
• The fascinating part is that nearly nothing coming from space exploration is both tangible and practical. There are research items made to further our understanding of science but they have no practical application by themselves (even if the knowledge they create is useful), and there's communication and observational data, definitely useful but not tangible. The anti-air missiles don't quite qualify as commodity, but they definitely were an industrial product, and you could say they were partially manufactured in space.
– SF.
Nov 2 '16 at 15:51