NASA isn't particualrly close to sending humans to Mars. Whatever Mars One says, as a society, we're closer to the brainstorming phase of how a piloted mission to the red planet would even work. One of the weird ideas that NASA architects have sketched out? Spaceship walls that are filled with water.
Vice talked to NASA's chief technologist, David Miller, about the concept:
Line your space shuttle with water and hey presto: you both help protect against radiation during the journey and transport a vital resource for your astronauts. “Water with hydrogen content absorbs radiation to some degree,” Miller explained. “Seeing as you need to take water, maybe you could line the walls of your capsule with water. So it’s used for drinking as well as shielding.”
The water would be replenished with purified astronaut waste. The design combines radiation protection, thermal control, and life support—not just in the form of drinking water but also algae, grown for food—thus reducing the overall weight of the spacecraft.
Plus, this system would not need to be that complex. So it's less likely to break down than other schemes for shielding the craft and supplying water. The only mechanical aspect are the pumps that push water from toilet waste through membranes to purify it.
Astronauts in low Earth orbit have been drinking recycled waste water since 2010. (It's purified with a spinning keg-sized device.) But even with an innovative water purifying system, astronauts would likely shower the way they do on the International Space Station: with babywipes.