systems. Alternatively, several heat exchangers 
inside and outside the pressure hull can be used. 
Both approaches must be evaluated to determine 
system layout, cost, and safety. 
Another approach employs thermoelectric de- 
vices adjacent to a particular heat source. This 
eliminates movement of large volumes of air but 
requires electrical hull penetrations to a hot plate 
outside. Thermoelectric air conditioning can also 
be used as a heater by the reversal of the power 
supply voltage. 
c. Water Supply Water is required at different 
degrees of purity: potable water for drinking and 
food preparation; fresh water for personal hygiene, 
and rinse water in sanitation, laundry, and dish 
washing. 
Fresh water can be supplied from storage 
tanks or extracted from sea water. For long 
missions and large crews, storage may be impracti- 
cal. Several types of fresh water machines are 
available. For very large installations, combination 
nuclear power generation and fresh water evapora- 
tion plants are possibilities. 
Vapor compression units have been used suc- 
cessfully on submarines and small surface ships for 
years; for steam driven ships, several firms offer 
reliable compact units. 
As part of water management, measures must 
be taken to minimize water discharge. For exam- 
ple, a system must be considered (similar to that 
used in commercial airlines) whereby toilets are 
flushed with water pumped at high velocity from a 
drain collecting tank. The tank will accumulate 
effluent from showers and other sources. 
In general, two basic water management con- 
cepts can be considered. The first is essentially a 
closed system incorporating various forms of 
regenerating waste water while storing on board 
waste products. It involves various filter processes. 
Little or no makeup water will be required in an 
efficiently operating closed system. 
The second system is the conventional open 
system that rejects unprocessed all waste water 
overboard and utilizes sea water distillation as a 
fresh water source. This is presently used aboard 
submarines. Fresh water from distillation is stored 
in central tanks. Additional unprocessed water 
may be used for flushing toilets. However, the 
differential between the normal internal atmos- 
phere and the ambient pressure of the depths 
argues for a closed system, especially as depth is 
increased. 
d. Food Supply The food supply can range from 
the prepared variety used by astronauts to the 
kitchen-cooked meals served aboard nuclear sub- 
marines. The latter require space, equipment, and 
additional atmosphere control equipment. Frozen 
meals with wide menu selection and well balanced 
diet could be furnished. Preparation would be 
minimal. Mission duration, crew size and composi- 
tion, power source, and logistic procedures will 
determine the most suitable system. 
e. Waste Disposal Solution of waste disposal 
must consider power and men available, mission 
duration, depth, and location of the habitat (or 
operating depth of submersibles). Freezing or 
chemical systems supported by between-mission 
replenishment would be most desirable for small 
to medium size crews (15 to 25 men) and less than 
120 days. 
However, for long missions and large crews 
some mechanical means must be utilized. Blowing 
sanitary tanks with compressed air (as in conven- 
tional submarines) requires greater amounts of 
energy with increased depth; this method becomes 
impractical at great operating depths. In addition, 
sewage must be removed from a habitat’s vicinity 
to avoid contamination of intake water and to 
prevent disturbing the scientific environment. 
A closed system could store all liquid wastes in 
a waste receptacle containing a chemical disinfect- 
ant to arrest bacterial activity. Garbage and fecal 
waste could be compressed, treated chemically, 
sealed in drums, and packed in freezer storage 
space as food supplies are consumed. Trash could 
be baled and stored. It is conceivable that little 
additional space and facilities would be required 
for a closed system. 
f. Habitability Much work is being done in 
human factors from a design viewpoint. In early 
design of habitats, little attention was paid to 
comfort, because major emphasis was on safety; 
however, that phase has passed. Because of con- 
centration on long periods of underwater habit- 
ability, attention has been focused on the human 
factors. 
Habitability has become a major factor in 
designing for sustained system effectiveness. Cer- 
VI-75 
