The concept is to design the next class of NASA spacecraft to be environmentally efficient. One designer is offering such a plan - and its fundamental design factor is "water". He boldly suggests that the walls of the spacecraft should contain water - primarily for radiation protection for the crew members - but also for virtually every other system task as well.
The water walls would also process urine and wash water, purge the CO2 from the air support system and even grow food using green algae - truly a page from mother nature.The idea's formal name is "Highly Reliable and Massively Redundant Life Support Architecture", but it's still not a reality yet since it's only recently become part of NASA's advanced concepts program. Getting this far means it has received additional funding for further study - and maybe even further system interlinks.
The water walls are envisioned to be an inner wrap-around of hexagon-shaped, multi-layered, interconnected polyethylene bags filled with the various bacteria, algae and filters to accomplish all its system duties. It is also designed to be as passive a system as possible - with the only mechanical element being the pumps required to move water into the appropriate places. All the former equipment needed for these tasks (compressors, evaporators, lithium hydroxide canisters, oxygen candles, urine processors, etc.) are no longer needed. Of course, these are also the very components that are most likely to fail. NASA considers the system highly redundant and is very interested in the integrated and passive nature of the entire concept. About the only need is for spare bags to replace used ones.