In a continuing program to study the habitability of space vehicles, the Manned Spacecraft Center investigated mobility of astronauts inside a space station, eating arrangements, constant wear intravehicular garments that are comfortable as well as functional, and the architectural arrangement of the interior space.

In another study, criteria were developed for use in determining when remotely controlled manipulators are more efficient than astronauts for extravehicular activity and when the astronaut can perform more efficiently. Marshall Space Flight Center will publish the criteria for use in system design and mission planning.

And, the Lunar Landing Research Facility and the standup cab developed and used by the Langley Research Center to study lunar flying vehicle dynamics were used by the Apollo 11, 12, and 13 crews for training. (Fig. 4-20.)

Life Support and Protective Systems

Life support systems for space missions of 30 days and longer will utilize regenerative processes to reclaim essential materials from human waste products. On missions which will not have resupply capability, the life support systems must operate at maximum efficiency to insure optimum use of the onboard materials. An

efficient life support system must be able to independently control liquids and gases flowing in zero gravity to and from various subsystems where they are processed at differing pressures, temperatures, and flow rates. Undesired mixing of the liquids and gases contaminates the liquid transport lines with trapped gas bubbles. The bubbles, carried downstream by pumps, cause inefficiencies and measurement errors, and may produce system failure due to gas blockage.

To overcome this potential source of trouble, the Langley Re

search Center began to develop a static two-phase separator capable of operating in zero gravity. Static separation of liquids and gases in a liquid transport line was achieved by using materials with different hydrophilic and hydrophobic characteristics. Fibrous porous Teflon and glass fiber cloth sprayed with Teflon proved to have the best hydrophobic qualities while stainless steel wire woven screen and nickel wire woven screen were the best hydrophilic materials.

Of several design configurations tried, the most successful in removing air from water in a spacecraft cabin is shown in Figure 4-21. The device employs the same principle as a water gun used in

the Apollo 11 and 12 spacecraft for hydrating the food (fig. 4-22). On those flights, the water was produced in the fuel cells at approximately 200 pounds per square inch absolute (psia) and was saturated at this pressure with hydrogen. Then the water was stored in a bladdered tank at 25 psia, and finally used at the cabin pressure of 5 psia. The total pressure reduction released approximately 8 percent by volume of hydrogen gas from solution at the point of use. On earlier missions without the gun this hydrogen caused problems for the astronauts. Use of the gun provided the astronauts with almost gas-free water for rehydrating food.

In another part of the life support program, a detailed analysis was completed on future life support system concepts and their integration with other systems in space vehicles for missions lasting up to 500 days. All subsystems were considered to be closed loop except for the food (food regeneration is not considered feasible before 1980 at least). All aspects of life support were reviewed, including atmosphere control and the recovery of oxygen from metabolically produced carbon dioxide, the regeneration and reuse of metabolically produced water, crew hygiene problems, food management, thermal and waste control, reliability and maintainability, and the unique problem of compartment replacement in zero gravity. It was concluded that future space vehicles should be equipped with a shower which would operate in zero gravity with the assistance of properly directed airflow, and that clothing

should be washed to reduce resupply requirements. The results are being used in space station studies and as a basis for directing research and technology efforts.

A prototype, lightweight contingency life support system was developed for the Manned Spacecraft Center by a contractor. The system includes three technologically advanced features: a "breathing vest" which allows for a fourfold reduction in helmet oxygen flow rates over the conventional flush system; a gas-operated pump for circulating coolant in the liquid cooled garment; and a lightweight (1 pound) sublimator for cooling. The total weight of the system for 0.38 hour operation is 30.6 pounds and for a projected 3.5 hour mission 39 pounds, still within the same volume envelope.

The system's most radical innovation is the breathing vest which is worn within the space suit. This unique element, weighing about 8 ounces, is responsible for reducing the amount of oxygen required to flow to the helmet area by a factor of four. At the same time, it maintains the level of inspired carbon dioxide within acceptable limits. Because of the fourfold reduction in oxygen flow requirements to the helmet, an open-loop design could be chosen. With an open-loop system design there is no requirement for a gas recirculation fan with its associated battery, for a condensate water removal system, or for a carbon dioxide absorbing system. Without these three subsystems, the portable life support system's weight, volume, and complexity are significantly reduced.

Biotechnology Flight Projects

Preparations were continued for key experiments to expand understanding of man in the weightless environment. In one such experiment, primates will be exposed to zero gravity for 6 months to 1 year; as the experiment progresses, physiological changes that take place down to the cellular level will be analyzed and evaluated.

During the period, fabrication was completed of a feasibility demonstration model of each of two competing designs for the life support and performance testing hardware that would operate in zero gravity without failure for the required long periods. Primates were tested with the equipment; the longest duration was a 56-day continuous run. Minor equipment failures occurred but the basic design appeared sound. The animals thrived in their life cells, put on weight, and increased their performance efficiency. (Fig. 4-23.)

In parallel with the tests, scientists at the NIH Yerkes Regional Primate Facility in Atlanta and at the University of Illinois were