ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 272 of 422
The data shown in Figure 4-24 suggest a mass of consumables of about 671 kg. Given that
consumables need additional hardware for storage and use, as well as the need to treat and store
the metabolic products, the use of an open-loop system seems favorable. The data strongly
suggest the use of open-loop systems except a recovery system for condensate. Furthermore, if a
fuel cell option is used for power generation, the product water could be used as consumable in
life support. Currently, such an option is estimated to produce roughly 800 kg of water, which is
more than the demand by the crew.
4.3.3.3 Hygiene water
The hygiene water allowance for the crew has been estimated to be 1l/crew/d. It is understood
that this figure is rather low. However, the supply could be supplemented by using the collected
condensate water, which amounts to approximately 1.42 l/crew/d. This figure is assumed to be
sufficient. For full body cleansing and hand washing, the crew would rely on wet towels similar
to those provided to astronauts on Russian spacecrafts.
4.3.3.4 Drinking water
The drinking water allowance for the crew has been estimated as follows. The water release by
the crew has been calculated using standard correlations based on the energy expenditure. A
literature review revealed that the water intake by the crew is about the same as to the water
release by the crew. Therefore, the amount of water intake has been calculated using the numbers
for the sensible and insensible water quantities. The advantage of this method is that the potable
water estimate is based on the energy expenditure.
4.3.3.5 Cabin atmosphere
The cabin atmosphere has been selected as follows:
Total Cabin Pressure: 50.0 kPa
Partial Pressure Oxygen: 25.0 kPa
Partial Pressure Nitrogen: 25.0 kPa
Partial Pressure Carbon Dioxide: TBD
Preferably, the atmosphere would be free of any contaminants. However, as a minimum
requirement, the spacecraft atmosphere shall adhere to the requirements given in ESA PSS-03-
401. Based on the experiences with long-term pressurised spacecrafts there shall be more
stringent limits on microbial contamination. The following limit has been proposed during this
study:
Total microflora count: 200 CFU/m 3 (CFU - colony forming units)