As far as humans are concerned, the most important part of a spaceship isn't the turbodrive or the turbolifts or even the turbolasers. No, it's the life support system, the thing that keeps us from, you know, dying. These systems are generally bulky and complex, but a new concept from NASA would weave them directly into spaceship hulls instead.
It's sort of ridiculous just how unsuited humans are for space travel. We're fragile little things, and we were only designed to operate within a very narrow range of environmental parameters. Really, it's too bad we're not all tardigrades, 'cause then we wouldn't need spaceships or space suits or anything at all. But until tardigrades take over from us (trust me, it'll happen eventually), life support in space is kind of a big deal, with astronauts requiring oxygen, fresh food and water and waste disposal (including removal of CO2).
NASA's new idea for replacing the complex machinery that's responsible for all of this stuff is a concept called Water Walls, which isn't an abbreviation for "Highly Reliable and Massively Redundant Life Support Architecture," but it's one and the same. Instead of relying on said machinery, Water Walls would be biological in nature, using hexagonal polyethylene bags full of filters, bacteria, algae and forward osmosis membranes to manage everything from solid and liquid waste to air processing. Algae would be an integral part of the process, providing a food source (albeit not a very tasty one) to astronauts, thereby completing the cycle.
The modular bags or tanks would be simple and cheap to construct and maintenance-free, and eventually they could form part of the outer structure of spaceships, providing both radiation protection and thermal management while saving mass over a dedicated system for either. Since there'd be a whole bunch of these cells, individual failures wouldn't be an issue, and exhausted units could be easily replaced with new ones. NASA suggests that this kind of tech could be used to sustain a crew in space over "multi-year" missions, and the agency has tossed $100,000 towards development of the concept.