Charles_West
09-10-2009, 05:27 PM
Third, and on a different track, is the idea of bypassing metals.
structural plastics are relatively strong, light and have uniform
properties. They can also be produced in industrial quantities. There
primary weaknesses are the loss of elastomers, UV degradation and thermal
sensitivity.
Plastics have been produced that do not have the first
weakness. I believe it is not too hard to produce usable plastics without
elastomers, but do not have hard proof.
UV resistant polyethylene has been produced for outdoor applications such
as sheds. There are several straight forward ways to deal with this
issue, ranging from carbon black to the stable organic compounds used in
sunscreen.
http://en.wikipedia.org/wiki/Sun_screen
Thermal control would require the use of insulators. Happily, high
performance insulators have been in development for a long time and this
is not a major issue.
To further support the feasibility of using plastics as a structural
material in space, read the following:
http://science.nasa.gov/headlines/y2005/25aug_plasticspaceships.htm
Assuming plastics can be used, the next hurtle is actually producing
large quantities in space. The essential materials needed for organic chemistry are carbon and water. If these could be found in the form of CO2 and water, it would be fairly straight forward to extract and purify them (especially compared to metals).
A possible reaction chain to produce plastics from these components using only heat would be using thermal reaction cycle to decompose water to produce hydrogen. (see http://en.wikipedia.org/wiki/Hydrogen_production) From there the Sabatier reaction (see http://en.wikipedia.org/wiki/Sabatier_process) could be used to create methane.
Once methane has been created, there is a wealth of prior work on making most common industrial organic chemicals (including plastics) from there.
Plastics may not be suitable for some roles but I think they might perform well for the structure of a habitat.
Potential problems are the availability of suitable chemicals in space (Are there asteroids that would have large amounts of both water and carbon?), the creation of a lightweight system that can perform the multistep chemical reactions required and the adaptation of current industrial chemical practice to space.
The major payoffs are ease of extraction (much easier to automate than with metal), purity of final product, formability of final product, completely thermally driven system and potential for large output per unit of system mass. Again, much of the development and testing could be done on Earth.
Thoughts?
structural plastics are relatively strong, light and have uniform
properties. They can also be produced in industrial quantities. There
primary weaknesses are the loss of elastomers, UV degradation and thermal
sensitivity.
Plastics have been produced that do not have the first
weakness. I believe it is not too hard to produce usable plastics without
elastomers, but do not have hard proof.
UV resistant polyethylene has been produced for outdoor applications such
as sheds. There are several straight forward ways to deal with this
issue, ranging from carbon black to the stable organic compounds used in
sunscreen.
http://en.wikipedia.org/wiki/Sun_screen
Thermal control would require the use of insulators. Happily, high
performance insulators have been in development for a long time and this
is not a major issue.
To further support the feasibility of using plastics as a structural
material in space, read the following:
http://science.nasa.gov/headlines/y2005/25aug_plasticspaceships.htm
Assuming plastics can be used, the next hurtle is actually producing
large quantities in space. The essential materials needed for organic chemistry are carbon and water. If these could be found in the form of CO2 and water, it would be fairly straight forward to extract and purify them (especially compared to metals).
A possible reaction chain to produce plastics from these components using only heat would be using thermal reaction cycle to decompose water to produce hydrogen. (see http://en.wikipedia.org/wiki/Hydrogen_production) From there the Sabatier reaction (see http://en.wikipedia.org/wiki/Sabatier_process) could be used to create methane.
Once methane has been created, there is a wealth of prior work on making most common industrial organic chemicals (including plastics) from there.
Plastics may not be suitable for some roles but I think they might perform well for the structure of a habitat.
Potential problems are the availability of suitable chemicals in space (Are there asteroids that would have large amounts of both water and carbon?), the creation of a lightweight system that can perform the multistep chemical reactions required and the adaptation of current industrial chemical practice to space.
The major payoffs are ease of extraction (much easier to automate than with metal), purity of final product, formability of final product, completely thermally driven system and potential for large output per unit of system mass. Again, much of the development and testing could be done on Earth.
Thoughts?