Shields Up!

The choice is clear: either fry in radiation or wrap yourself in crap.  Inspiration Mars will gradually peel bags of food, or their contents, off the perimeter of the vessel and replace them with dehydrated human waste packets, going from a water-and-food shield to a poo shield.

I am not making this up.

Water has long been suggested as a shielding material for interplanetary space missions. “Water is better than metals for protection,” says Marco Durante of the Technical University of Darmstadt in Germany. That’s because nuclei are the things that block cosmic rays, and water molecules, made of three small atoms, contain more nuclei per volume than a metal.

Water shielding also has another benefit – you can drink it. Such dual use is essential aboard a spacecraft, where space is at a premium. Applying this rationale, the Water Walls concept involves polyethylene bags that use osmosis to process clean drinking water from urine and faeces.

Lining the walls of a spacecraft with layers of these bags creates a 40-centimetre-thick liquid shield. All of the bags would initially be filled with drinking water. The crew would then fill other bags with waste during the trip to Mars and swap them out for the now-empty water bags.

The osmosis-based processing is much simpler than the automated life-support systems aboard the International Space Station, making it less likely to fail during the long ride to Mars.

However, there are problems to be ironed out. The urine-to-water processing bags were tested in orbit on the last ever flight of the space shuttle in 2011 and found to be 50 per cent less efficient in microgravity than in ground-based tests.

Along those lines, may I suggest a product first proposed in 1973 that might ease the passage?