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VISUAL PROBLEMS OF SPACE TRAVEL1 The types of space flight which may be undertaken in the immediately foreseeable future and the delineation of their phases are introduced briefly. Following this discussion, several specific prob- lem areas along with potential lines of investigation are suggested. The final section of this report is concerned with the role man can play in a space mission. The emphasis is on the visual mechanism and how it can be used effectively to increase the probability of success rather than simply to aid survival. Space Flight Missions "In the immediately foreseeable future we can anticipate three basic kinds of manned space flight missions. The first of these will be orbital flight around the earth, the second will be a lunar flight, and the third will be inter- planetary flight within our own solar system." "Orbital Flight "Orbital flights around the earth will be at altitudes which range from approximately 100 miles to approxi- mately 500 miles. The minimum altitude is established This report draws especially heavily upon the content of a previous report, "Sensory and Perceptual Problems Related to Space Flight," by John L. Brown, NASâNRC Publication No. 872, 1961. Large seg- ments of that report are quoted herein, with minor editorial emenda- tions. These quotations are set off from the remaining text of this report by indentation and single spacing, with brackets indicating editorial changes. Occasional short quotations from the Brown report have not been referenced in the usual manner. 1
by the increasing aerodynamic drag which is provided by the earth's atmosphere as altitudes are reduced below 100 miles. The maximum altitude is imposed by the location of the Van Allen radiation belt at altitudes above approxi- mately 500 miles . . . . " "Lunar Flight "A flight to the moon would consist essentially of the placement of a vehicle in an orbit about both the earth and the moon. The flight would probably consist of a single trip to the region of the moon for the purposes of photog- raphy followed by immediate return to earth. . . . [Subse- quent to a circumlunar flight, both hard and soft landings will be attempted.]" "Interplanetary Flight "Interplanetary flight will be accomplished by launching vehicles from the earth at velocities such that they can escape the gravitational field of the earth and enter into their own orbit about the sun. . . . "It seems certain that as in the case of orbits around the earth, interplanetary flight will be along preselected routes and there will not normally be gross alterations in vehicle flight path en route, even after propulsion systems which may afford the continuous application of thrust have become available. [Thus, external visual navigation will not play a dominant role other than as a check on the auto- matic navigational equipment.] The time when sufficient energy will be available for radical changes of flight path en route is a long way off and problems related to this kind of flight will not be considered." Another extremely important phase of manned space flight is that of accomplishing landings on surfaces other than earth. "Two types of vehicle landings may be considered. These will be classed as aerodynamic landings and reaction landings (Brown, 1961)." Al- though external vision will not play a major role during interplanetary flight, it is entirely possible that visual functions will be important in achieving successful landings on alien planets or on the moon.