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We are bags of mostly water, about 60%, with the brains pushing 75% and lungs over 80%. When humans go into space, the second consideration after air (and air pressure) is water. With air, we face a volume transport problem – but air does compact nicely; though runs toward the explosive during the unpacking. Water, though, is a weight problem and nearly all the hard-to-impossible-to-solve problems with space travel so far have been weight problems.
How does one get off the planet? Fight the weight of gravity. How does one travel through space? Fight the weight of inertia. Every pound in space requires a force to get it off the planet and moving where we will want it to go. Places like the Moon for training and exploration, Mars for first stage colonization testing, and other stars for immigration.
All the best situations for long-term habitation in space are to have water already be there at the end. Yes, we can (and are) studying every manner recycling of water during the journeys. Controlling a dozen gallons per person recycled in a closed system has been challenging. Forward osmosis is just one of the many processes being studied.
But for colonization, where the need for water will be hundreds of gallons per person – not a few dozen – between the requirements for crops and manufacturing and washing and population growth, water must be at the other end.
We are beginning to find it among the exo-planets. Our tech isn’t *quite* there yet – new cameras and satellites are coming on line to double-check initial findings. But we have some suspects. Each step, each discovery, brings us that much closer to the stars.
Bibliography
Astrobio.net. “Recycling water in space”. phys.org. 2011 June 20.https://phys.org/news/2011-06-recycling-space.html – last viewed 1 November 2019.
Damadeo, Kristyn. “NASA and Partner Announce Finalists in the 2019 Mars Ice Challenge”. nasa.gov. https://www.nasa.gov/feature/langley/nasa-and-partner-announce-finalists-in-the-2019-mars-ice-challenge – last viewed 1 November 2019.
Ghosh, Pallab. “Water found for the first time on ‘potentially habitable’ planet”. BBC News Science & Environment. 2019 September 12. https://www.bbc.com/news/science-environment-49648746?SThisFB – last viewed 1 November 2019.
Siegel, Ethan. “Does water freeze or boil in space?” medium.com. 2016 Dec 10. https://medium.com/starts-with-a-bang/does-water-freeze-or-boil-in-space-7889856d7f36 – last viewed 1 November 2019.