331 lines
15 KiB
Plaintext
331 lines
15 KiB
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(word processor parameters LM=8, RM=75, TM=2, BM=2)
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Taken from KeelyNet BBS (214) 324-3501
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Sponsored by Vangard Sciences
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PO BOX 1031
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Mesquite, TX 75150
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July 5, 1990
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Space Vision Anomalies
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A Review of the Literature
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by
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LAMBERT T. PARKER
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courtesy of Double Helix BBS at 212-865-7043
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Ocular & Visual changes in space.
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Before we begin talking about the odd effects of space on vision,
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we need to agree on some definitions.
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These are:
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VISUAL THRESHOLD: the minimum amount of light that elicits a
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sensation of light.
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VISUAL ACUITY : the degree to which the details and contours
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of objects are perceived.
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Visual acuity is usually defined in terms of
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minimum resolvable separation.
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Threshold is a complex phenomenon, depending heavily on conditions
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within the eye and in the surrounding environment. Conditions such
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as optical factors, the state of the image forming mechanisms of the
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eye;retinal factors, such as the state of the cones; stimulus factors
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such as illumination, brightness of the stimulus, contrast between the
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stimulus and the background, length of time exposed to the stimulus,
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and so on; and other, random factors.
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Minimum separation is the shortest distance by which two lines can
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be separated and still be perceived as two lines. People with sharp
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vision can resolve lines which are very close together. People with
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less sharp vision must either move closer to the target (increasing the
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apparent separation), or move the lines farther apart (increasing the
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actual separation).
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Taken together, these two measures are reasonably accurate
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measures of the overall state of a persons vision. It is said eyes are
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the windows into man's soul. The importance of the organs of sight
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cannot be over-emphasized. The visual system, eyes and brain, are a
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navigation system which can measure distance through stereoscopic
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vision, detect motion, focus from the tip of the nose to infinity,
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recognize a multitude of colors, shades and shadows, adapt to a wide
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range of lighting conditions, coordinate an average 70 kg male/female
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in motion as complex as a ballet or as exacting as threading a needle.
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It operates through a zillion neural interfaces in a system
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thousands of times more powerful than the most advanced computer, and
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does it all without any conscious thought at all. You simply decide
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that you want to do thus and so, and it is done.
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Page 1
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For all its amazing versatility, vision is a specialized system.
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Human visual hardware is a result of a billion years of evolution
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within the earths atmosphere where light is scattered by molecules of
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air, moisture, and particulate matter.
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But as we ascend into our atmosphere light distribution is
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changed, due to the decreasing density of the air. The visual system
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receives information differently. Sometimes this can result in odd,
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even astounding, visual effects.
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Gemini 4 astronaut Edward White reported seeing networks of roads
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during his space walk, and so did cosmonaut Nikolayev from Vostok 3 as
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early as 1963. "During the day, the earth has a predominantly bluish
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cast.....I could detect individual houses and streets in the low
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humidity and cloudless areas such as the Himalaya mountain area. I saw
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a steam locomotive by seeing the smoke first..... I also saw the wake
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of a boat on a large river in the Burma-India area...and a bright
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orange light from the British oil refinery to the south of the city
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(Perth,Australia.)"
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The above observation was made by Gordon Cooper in Faith 7 [1963]
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and it generated much skepticism in the light of the thesis by Muckler
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and Narvan "Visual Surveillance and Reconnaissance from Space Vehicles"
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in which they determined that a visual angle of ten minutes was the
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operational minimum possible for humans, and that the minimum
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resolvable object length [M.R.O.L] at an altitude of 113 miles would be
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1730 ft.
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This limitation of acuity was revised the next year to 0.5 seconds
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of arc for an extended contrasting line and 15 seconds of arc for
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minimum separation of two points sharply contrasting with the
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background.
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So how could these astronauts "see" objects much smaller than
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this? The answer is that the eye isn't the entire visual system.
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There is a mind intimately connected with the eye, and the mind is
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capable of inferring details where none can be seen. Orbiting at 237
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miles in Skylab it was possible to see the entire east coast [Canada to
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the Florida Keys] and resolve details of a 500 feet long bridge based
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on inference.
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Of interest is the fact that even though a mechanical eye [camera
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system] can resolve objects greater than fifty times better than the
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human eye, without human ability to infer, people, possessing the
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ability to infer, can match that performance--or even surpass it. That
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leads us to our first conclusion, the first observed difference between
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visual performance on earth and visual performance in space: Visual
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acuity in space exceeds that of earth norm when objects with linear
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extension such as roads, airfields, vessel wakes, etc.
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An ability called by some the "Search Light Effect". This is a
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positive factor. In space, vision is sharper than it is on the ground.
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The next factor is not so positive. In fact, it can be a grave danger
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to anyone working in the space environment.
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We judge distance by the mechanism of stereoscopic vision. It
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works by fusing the twin images impinging on the eyes, combining them
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into one image, and producing a sense of distance. This system relies
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on reference points. One object overlaps another, or the images
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Page 2
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received in either eye are slightly different.
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You can demonstrate this to yourself by simply looking into a
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mirror. As you look, close one eye. You see one side of your face
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slightly more than the other. Now look through the other eye. You see
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the other side of your face. Now, with both eyes open, you can see
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your face and somewhat of both sides, and along with that visual
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impression you have a sense of how far away you are from the image.
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The sides of your face, perceived unequally in either eye, are
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reference points for distance. In space one has to deal with a poverty
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of reference points. For hardware evolved in a reference oriented
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paradigm this poses a grave problem, once out of the space craft gazing
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outward the eye can only fix on the stars [without even a twinkle]
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which for all practical purpose is at infinity.
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This induces a state called "Empty field myopia". Empty Field
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Myopia is a condition in which the eyes, having nothing in the visual
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field upon which to focus, automatically focus at about 9 feet.
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An astronaut/cosmonaut experiencing empty field myopia focusing at
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9 feet would be unable see objects at a range as close as 100 feet. If
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another spacecraft, satellite, meteorite or whatever entered his field
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of vision, he or she would not be able to determine either its size or
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its distance.
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That is our second conclusion: Vision in space is very subject to
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a lack of visual reference points, a condition which induces a state of
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visual "neutral lock" known as empty field myopia. Is there a
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solution? Man does not face any hostile environment in his birthday
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suit, the clothing industry and walk-in-closets say it all.
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In space we will wear our exoskleton just as we wear winter
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jackets in winter. We will wear our helmets with visors to maintain
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our internal environment, filter out all those nasty rads etc.
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Since empty field myopia is a result of loss of reference points,
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why not just build them into the visor itself? Give the eye points of
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reference. Create a virtual reality? This line of speculation leads
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to amazing concepts.
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To learn more about the concept of virtual universe in the helmet
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read: Journal: Air & Space, [Smithsonian Publication]
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Article: Big Picture by Steven L.Thompson.
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illustrated by Dale Glasgow.
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About the creation of a virtual universe with new computers and
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software in the helmets of F-16 fighter pilots--this is not a
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theoretical posibility but a reality. There is another downside to the
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performance of human visual systems in space.
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One aspect of a adaptation to microgravity [space sickness] is an
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increased dependence on visual as opposed to vestibular mechanisms in
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the stabilization of the retinal image during head movement.
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This phemonemon only underscores the importance of being aware of
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our visual ability. This is our third conclusion: Microgravitational
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effects on the human visual/orientation system can cause unpleasant or
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even debilitating effects.
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Page 3
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As if that weren't enough, studies done by the Russians on
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cosmonauts on effects of perception of colors in space suggests a
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reduction in the perception of brightness of all colors. Greatest
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degradation seems to occur in purple, azure, and green.
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Conclusion number four: Visual perception of color is impaired in
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the space environment, with implications for color coded reference
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systems.
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And, finally, there are the light flashes. Not the so-called
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fireflies noted in orbital flights by astronauts [shown graphically in
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the movie "The Right Stuff"] but lights perceived as faint spots or
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flashes seen after dark adaptation in the cabins of the Apollo
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missions.
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These light flashes described as white or colorless have been
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classified as three types:
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1) Described as "spots" or "starlike" objects 66 % of the time.
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Appearing in both eyes simultaneously or one eye at a time.
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2) Described as "streaks" 25 % of the time.
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3) Described as "lightning discharge seen behind clouds" 9 % of
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the time.
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It is of interest that the very same astronaut who reported them
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in the Apollo flights failed to see them in previous Gemini flights.
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After the Apollo flights this phenomena was noted by the crew of all
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three Skylab missions especially when they crossed the South Atlantic
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Anomaly.
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W.Zachary Osborne, Ph.D., and Lawrence Pinsky, Ph.D., at the
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University of Houston & J.Ver on Bailey at Lyndon B. Johnson Space
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Center conducted an investigation of this phenomena and concluded that
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it was due to heavy cosmic radiation penetrating the craft.
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The fact that the effect was noted only after the eyes were dark
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adapted confirmed retinal interaction rather than interaction with
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optic nerve.
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Which brings us to our last conslusion: Radiational effects and
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light flashes, can be a problem to future space travelers.
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These are not the only effects that we will (literally) see as we
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explore and move out into space. They are, however, a significant
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divergence from normal human vision, and must be taken into account in
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both the planning and execution of future construction workers living
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and working in space, and it must be taken into account.
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Failure to do so can be costly, both in terms of time lost and
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valuable equipment damaged or destroyed. It can also be fatal. To the
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construction worker who fails to see a moving object coming toward him.
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To the pilot that misjudges an approach, or to anyone in that
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environment relying on vision for safety.
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Page 4
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These are the effects: Unusual visual acuity
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Empty field myopia
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Space sickness
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Lost color perception
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Light flashes
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They must be taken into account during the planning and execution of
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any space mission. Failure to do so can be costly...or fatal.
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--------------------------------------------------------------------
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If you have comments or other information relating to such topics as
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this paper covers, please upload to KeelyNet or send to the Vangard
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Sciences address as listed on the first page. Thank you for your
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consideration, interest and support.
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Jerry W. Decker.........Ron Barker...........Chuck Henderson
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Vangard Sciences/KeelyNet
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--------------------------------------------------------------------
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If we can be of service, you may contact
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Jerry at (214) 324-8741 or Ron at (214) 484-3189
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--------------------------------------------------------------------
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FINIS
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Page 5
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