TOTAL SUSTAINABILITY A survival system with just a protective enclosure will only provide shelter against specific hazards during the initial threat period. A survival system which encloses life support systems will provide shelter and sustainment for a period which depends on the life support systems capabilities and endurance. All advanced Life Support Systems include an energy system or systems that are fundamental to the operation of the LSS and hence underpins the operation of the LSS. Consequently, the energy system(s) must be highly reliable and have in-built redundancy and reparability. A 4-star system recycles life support materials, a 5-star system can also repair this equipment from spares and a 6-star survival system has total sustainability as it recycles not only the life support materials but all the other materials from which the total survival system is made. Occupants within a 6-star survival system will have the ability to repair the equipment that provides these three aspects: the containment protective environment, the life support system and the life support material recycling system that allows the life support system to continue indefinitely. That is, the occupants have both the means and training to be able to maintain and repair all of the structures, machinery, component parts, service distribution and recycling systems of their entire survival system. It will be necessary to be able to affect such maintenance and repairs within the timeframe that subsystems can be temporarily switched off and with the available tools and skills of the occupants. This requires advanced LSS to be designed as man-machine systems, which can be greatly facilitated by well-designed easily repaired equipment with associated maintenance & repair training systems. NASA is already manufacturing some components on the International Space Station with a 3D printer. On Earth systems already exist to recycle 3D printed parts to produce new 3D printer filament that is then a stock of input material ready to produce new parts when required. There is currently only a very limited range of materials that can be recycled indefinitely, including aluminium and some plastics, but the list of such materials is growing.