Long-term feeding in space depends upon a payload of stored food unless
food is produced during flight. If sufficient propulsive energy is
available, the duration of missions using stored food may be quite long.
However, in emergencies in which a mission lasts longer than planned,
survival may depend on the ability to produce food extraterrestrially.
Eventually it will be desirable or necessary to produce food beyond the
confines of Earth.
The nutritional requirements of the crew will be influenced by such
factors as activity, physical and psychological stress, individual size
of the members, and individual metabolic rates. The food intake will
have to be adjusted to meet these requirements. It is necessary to know
the nutritional requirements of each astronaut and the way in which
these are altered by the conditions of space flight in order to estimate
needs on long missions. Without this information, the food supplies for
the longer flights may be too much, too little, or improperly balanced.
Where dependence would not be on stored food alone, but on food produced
en route, more exact information on requirements is needed to determine
the capacity of food production units.
In the discussion of bioregenerative systems, it was suggested that food
materials could be produced by photosynthetic organisms (e.g., algae,
duckweed, and other higher plants) or by nonphotosynthetic organisms
(e.g., _Hydrogenomonas_). In contrast to the use of living organisms,
reprocessing waste materials by chemical treatment or the actual
synthesis of high-energy compounds has been suggested. No chemical
system has yet been demonstrated as workable for the economical
production of food in space, and the systems considered produce
materials which may be converted to food, but are not food as such.
Algal cultures have had the most extensive investigation as food in
space, but the technical problems of using this material as a food
source have not yet been solved. It is apparent from the investigations
to date that algae will require treatment before they can be used as
food. In limited trials, difficulties have been experienced with amino
acid deficiencies, digestibility, high residues, and gastric distress.
Processing methods which would be applicable in space travel and the
possibility of secondary conversion by other animals or plants should be
systematically investigated.
chapter 8
_Significance of the Achievements_