Last time we had a look at how we would go about avoiding breathlessness on board the Erikson. This post, we consider how a lack of H2O may impact on water fights during travel. I guess the whole needing water to survive more than 3 days is important too…
Water Reclamation System
We touched on this briefly when we looked at oxygen but lets focus now on the water side of things. The system chemically treats liquids, producing water that astronauts can drink. The waste water is first cleansed of its free gas and solid matter, such as hair, before being passed through a number of filtration beds that clear out more contaminants. The last remaining chemicals and micro-organisms are removed through a high-temperature catalytic reaction. Urine, one source of waste water, also goes through a process of distillation after which is fed through the water processor(1).
This system has helped reduce the amount of water that the ISS depends on Earth for but not to the point complete independence. The WRS isn’t enough to allow the ISS, in this instance, to become completely self-sufficient and the Erikson won’t have the luxury of having Earth as its neighbour for the flight to Mars. In addition, the filtration beds are indestructible and repeat use will ultimately result in a breakdown of the beds. This isn’t too great a problem as additional filters can be included in supplies but the system may also be needed on Mars in the initial weeks/months of set-up.
Drawbacks aside, the WRS does provide a reasonably viable solution to the water problem. Provided our astronauts are well hydrated a steady stream of water should be available and it means that one less bio-product goes to waste (Wee don’t want to have to deal with unnecessary waste).
Alternative Water Processor
Whilst the prospect of filtered urine might sound okay (In the context of long-distance space travel), the filtration beds aren’t the most sustainable means of filtering waste water. The AWP uses a combination of a biological water processor (BWP) and an advanced membrane processor (Forward Osmosis Secondary Treatment (FOST)) which eliminates the need for such beds. Waste water is passed through the membrane where in undergoes both nitrification and denitrification, a process which that oxidises ammonium salts (found in urine) to create nitrates (less harmful)(3). FOST then implements the use of Forward and Reverse Osmosis, the movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane (4), to create fresh water.
During a 300 day testing period, the BWP performed well, removing 85% of the carbon and 44% of the nitrogen found in the waste water sample. FOST has managed to retrieve, on average, 93% of the water in samples with a maximum of 98%(2). This indicates that the AWP is not only a viable solution to the water problem but a more reliable one, rising above the problem of biofouling seen with WRS.
It’s (current) 300 day life span does raise a few concerns as our voyage will be somewhere in the region of 6 months (336 days give or take). That being said, there is room for improvement so it could be made to cover the whole flight.
These solutions, at present, provide the best solutions to the problem of water. Lugging great ice blocks across the galaxy isn’t overly safe as water has a tendency to expand when frozen which isn’t great in a pressurised environment (As cool as a Fortress of Solitude in space would be, it becomes considerably less cool with dead astronauts floating inside it. There is an option to carry water reserves but in terms of long-term supply the WRS and AWP both provided a fairly sound solution, the AWP edging further ever so slightly with it’s more sustainable means of cleansing.
Do you have any suggestions for how our astronauts can
maintain some fancy water features on-board produce enough water to get them to Mars? Please leave them in the comments along with any other general thoughts or questions. Thank you.
- Lou Brown (2008), New Water Reclamation System in Space [online] Last Accessed 15 September 2017: http://bjwsa.org/newsrelease/new-water-reclamation-system-in-space/.
- Daniel J. Barta Ph.D., Karen D. Pickering Ph.D., Caitlin Meyer, Stuart Pennsinger, Leticia Vega, Michael Flynn, Andrew Jackson Ph.D., Raymond Wheeler Ph.D. An Alternative Water Processor for Long Duration Space Missions, 40th COSPAR Scientific Assembly (2014), ADS, pp.1, https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013115.pdf
- Merriam Webster (2017), Nitrification [online], Last Accessed 15 September 2017: https://www.merriam-webster.com/dictionary/nitrification
- BBC Bitesize (2017), Osmosis [online], Last Accessed 15 September 2015: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/cells/cells4.shtml