Within the range of life support systems, numerous potential applications of nanotechnology arise. As substantial tasks of life support systems in space travel, the following should be mentioned:
• O2-/N2 supply,
• Pressure monitoring,
• Heat absorption and rejection,
• Waste water treatment,
• Monitoring of water quality,
• CO2- removal,
• Air cleaning and filtration,
• Control of air quality and humidity.
Potential Applications for Nanotechnologies in Life Support Systems
According to statements of NASA, no applications of nanotechnology are registered within these ranges so far. As potential applications, however, the following topics were mentioned:
• Gas storage (high-efficient nanomaterials with high capacity-weight ratio primarily for nitrogen and oxygen storage, possibly as spin-offs of hydrogen storage developments).
• Waste water treatment (here at present activated charcoal filters and ion exchangers are used, potentials are seen for regenerative nanomembranes).
• Sensors (e.g. for monitoring filter processes within the range of water purification, for monitoring the air quality in space stations by means of electronic noses or for the detection of pathogens).
• Heat exchangers (so far, heat exchangers are one of the largest and heaviest life support systems on the International Space Station (ISS); therefore, a high demand for weight reduction and miniaturization by means of nanostructured materials with more efficient heat exchange and transfer properties is existent).
Electronic Noses, Gas Sensors, Arrays of Gas Sensors and Chemometric Pattern Recognition
Some developments should be noticed within the range of so-called electronic noses for the monitoring of air quality in manned space stations, or also for early fire warning. Different types of gas sensors can be used for such applications, e.g. metal oxide sensors, Schottky diodes or thin polymer films, which were deposited as nm to micron thick coatings on aluminium substrates and form electrical resistance varying with the absorption of gaseous molecules. Unfortunately the selectivity of gas sensors is quite low. Therefore, arrays of a multiplicity of sensors are usually used, which produce specific signal outputs in dependence of the air composition. A chemometric pattern recognition allows a reliable identification of gaseous analytes, whereby several analytes can be determined at the same time.
NASA’s Testing of Electronic Noses
The Jet Propulsion Laboratory of NASA developed an electronic nose, which has already been tested successfully in a space shuttle mission and which should be implemented on the International Space Station (ISS) in the future. In this range, nanotechnology might provide approaches for miniaturization and improvement by more selective and sensitive sensors.
How Nanomembranes Can Improve Water Purification Systems
In the area of water purification, nanomembranes offer the possibility of an efficient removal of pollutants and germs. At present, nanoporous ceramic filter membranes for the sterilization of treated water are developed by the company, Argonide, in the frame of a Small Business Innovation Research (SBIR) project of NASA. Such nanomembranes, based on nanostructured aluminium fibers, can remove viruses very efficiently and are less susceptible against pore blockage than conventional membranes. For the future, there is still a huge potential for applications of nanotechnology for life support systems in human space flight.