[15] The feeding requirements for the Manned Orbiting Laboratory (MOL) are not the result of or developed by the feeding system. Rather, these requirements are imposed on the feeding system by conditions or factors external to it. The particular type of mission, the spacecraft design and engineering, and the very nature of space travel impose restrictions on the feeding system.

The mission of the MOL requires that two men be fed for 30 days. This requirement presents a great challenge because of the length of the flight. Much greater emphasis must be placed on the variety, acceptability, and convenience of the foods than would be necessary for a shorter flight. Variety and reduced repetition is essential to prevent food monotony, so a 6-day menu cycle has been established rather than the usual 3- or 4-day cycle. A sufficient number of acceptable foods must be available to fill the menu. A screening test is required during the development of a space food; each item must be rated at least 6.0 on a 9-point scale by a small, trained panel at two different stages of development. The true degree of acceptability will be measured by the results of long-term chamber simulator runs and crew-feeding tests. Each 6-day-cycle menu will be individually tailored by a computer to the preferences of each pilot. It is realized that the foods must be acceptable or sufficient nutrients will not be consumed.

Convenience influences acceptability, consumption, and morale and thus is a requirement levied on the feeding system. No one likes to spend time preparing food nowadays, least of all a pilot in a spacecraft. In an effort to minimize preparation time, the food for a day is divided into three snacks, a main meal, and a separate package of beverages (table 1). In order that convenience can be measured, time requirements have been set. Ten minutes is allowed for the retrieval and preparation of each snack meal, and a total time (including consumption and waste stowage) of 45 minutes is allowed for the main meal.

Rehydration time and handling are factors in determining convenience, and as such become measured quantities. Any one item can take up to 10 minutes to be rehydrated, but the average time for all items must be 5 minutes or less. The manipulation time allowance, which is the time to retrieve, open, and inject water if necessary, is a maximum of 5 minutes for any one item with an overall average time of 2 minutes.

The food packages and overwrap are to be color coded to identify each crew member's food, and each cell of the food stowage liner will be identified as to day of use.

The design and engineering of the spacecraft impose certain constraints on the feeding system. The MOL will have a food installation, where the pilots will eat, separate from the other work areas. This feeding console has two food stowage compartments, one above the other and one for each pilot. An area above the compartments contains the water dispensers, package opener, and other accessory items. Inside each compartment, which is approximately 25 by 15 by 17 inches, is a nylon food stowage liner. This liner is divided into 16 cells. Each cell is about 6 by 4 by 17 inches and will hold two ration packs, that is, food for one man for two days. One cell will be empty and will be used to store the food wastes from the first 2 days. The compartments provide 195 cu in. in which to store enough packaged food for one man for one day.

The weight allowance for one man for one day is 1.7 lb. If the food contains the desired 4.9 Kcal/g it must weigh about 1.17 Ib; 0.53 lb, or about 33 percent of the total weight, is left for packaging.

The packaged foods must withstand maximum temperature and relative humidity of 100° F and 100 percent, respectively, and an atmosphere of 70 percent oxygen and 30 percent helium with a pressure of 5 ± 0.2 psia.

[17] The water is provided by the fuel cell, and a silver ion generator provides for suppression or control of microbiological contaminants. The water has a pH of 6 to 8 and the system is capable of providing 22.6 fluid oz of potable water at 40° to 70° F and at 145° to 155° F at any one time. The cold water is dispensed in 1/2 -oz increments and the hot, in 1-oz increments. Both are transferred at the rate of 5 fluid oz/min with the delivery pressure maintained within 26 to 33 psia. The water system has a daily capability of about 2600 ml per crewman.

The packaging materials are restricted by the flammability and offgassing requirements which apply to all nonmetal materials in the spacecraft. There are established standards for determining these requirements.

Man requires a special feeding system when he travels in an artificial environment through the weightless voids of space. The food must be nutritionally adequate. The effects of the stress and conditions of space travel on the metabolic requirements of man are not completely known, but the figures in table II are based on our best experience to date. These requirements will be used as constraints in the computer selection of menus for individual crew members. Nutritional adequacy becomes especially important for a flight of 30 days. Caloric distribution of the ration has been set at 27 to 34 percent fat, 10 to 15 percent protein, and 50 to 58 percent carbohydrates

The foods must be compatible with the pilots; that is, they must neither produce gas nor cause constipation, diarrhea, or any other gastrointestinal upset. This can be best determined during the simulator tests at the School of Aerospace Medicine and the crew-feeding tests.

There are no firm requirements at this time as to the size of the individual bites of food or the rehydratable portions. These factors are being studied to determine the best and most efficient size or sizes.

[18] Strict food safety is a requirement of all space--feeding programs. The use of a clean room for the production of MOL foods is required, as is minimum delay in processing to avoid excessive exposure of foods to oxygen and moisture. ln addition, the producer must keep records of ingredient origin and production history for each end food item. The microbiological standards for MOL foods are given in table III. They are the same as or quite similar to those used for other spaceflights.

When one travels in a closed environment in space, food wastes must be treated to prevent the formation of gas, growth of microorganisms, or production of any noxious or toxic substances for the days under ambient spacecraft conditions. The chemical agent 8-hydroxyquinoline sulfate has been used.

Foods for space travel must be specially packaged. The packaging and packing requirements are:

(1) Packaged food and overwrap:

(a) Evacuated and flushed 3 times with purified nitrogen at 2 to 3 psig and then evacuated to 2 mm or less mercury absolute pressure.

(b) 16 to 24 hr after sealing each package or pack is subjected to a vacuum integrity test.

(2) Packaging material:

(a) Peel strength, 200 g/in. width at 50 mm/min.

(b) Heat-seal strength, 1850 g/in. width at 50 mm/min.

(c) Burst pressure, greater than 9 psig.

The packaged food cannot be put on a spacecraft unless it has been tested to ensure that it will withstand the rigors of space travel under the conditions it may encounter. Therefore, the food items, in addition to the usual quality control and inspection during production, must undergo flight qualification testing. This consists of four tests, the 30-day environment, acceleration, vibration, and acoustical tests, as follows:

[19] (1) Chamber environment, 30 days:

(a) Evacuate to 50µ pressure and hold until temperature reaches 95° ± 5° F.

(b) Repressurize with heated, humid gas composed of 70 percent oxygen and 30 percent helium.

(c) Temperature cycled 20 times between 95° F and room ambient temperature.

(d) Completion - examine package and food for defects.

 

(2) Acceleration 5G forward and 2G aft when food in operative mode and 0. 5G along two perpendicular lateral axes or 5G along three orthogonal axes; test duration, 2 min.

 

(3) Vibration: 10 to 2000 cps on each of three principal orthogonal axes; test duration, 3 min.

 

(4) Acoustical: 118 to 128 db over six typical octave bands.

In order to obtain space foods that meet the many specified requirements it is necessary to have good, realistic production documents for each item. The development of adequate spacefood production documents is a requirement of our system.

These are the requirements around which the feeding system must be designed. Although they are restrictive, a good feeding system can still be provided. By proper management and design it may be possible to gain some leeway in weight and volume. In cases where a significant improvement can be made in the feeding system by changing a requirement, attempts will be made to change the requirement.

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