Development of Water Treatment Systems for Use on NASA Crew Exploration Vehicle (CEV) and Lunar Surface Access Module (LSAM) 2006-01-2012
NASA is currently developing two new human rated launch systems. They are the Crew Exploration Vehicle (CEV) and the Lunar Surface Access Module (LSAM). Both of these spacecraft will require new life support systems to support the crew. These life support systems can also be designed to reduce the mass required to keep humans alive in space. Water accounts for about 80% of the mass required to keep a person alive. As a result recycling water offers a high return on investment. Recycling water can also increase mission safety by providing an emergency supply of drinking water.
This paper evaluates the potential benefits of two wastewater treatment technologies that have been designed to reduce the mass of the CEV and LSAM missions. For a 3 day CEV mission to the International Space Station (ISS) this approach could reduce the mass required to provide drinking water by 65% when compared to stored water. For an 18 day Lunar mission a mass savings of 70% is possible.
These technologies also increase safety by providing a lightweight back up to stored supplies. They allow astronauts to meet daily drinking water requirements by recycling the water contained in their own urine. During a 3 day CEV emergency return to Earth this capability could be critical to the crews' survival.
These technologies also convert urine into a concentrated brine that is biologically inactive and can be safely stored onboard. This eliminates the need to have a dedicated vent to dump urine overboard. This would result in one less through hull fitting on the CEV space craft.
The first technology discussed is a urine treatment pouch that converts urine into a fortified sports drink, such as Gatorade or Countrytime™ lemonade. This system is referred to as the urine cell. The second is a small isothermal membrane distillation apparatus that converts urine into pure water. This system is referred to as an osmotic distillation (OD) system. Both systems are based on commercial technologies. In this paper preliminary design concepts are provided, predicted mass equivalents are calculated, and a return on investment is estimated. Work evaluating these systems has only recently been initiated. As a result all data provided in this paper should be considered preliminary.