Space Vision Anomalies

 

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                                     July 5, 1990

                                Space Vision Anomalies

                              A Review of the Literature

                                          by

                                  LAMBERT T. PARKER

                     courtesy of Double Helix BBS at 212-865-7043

                          Ocular & Visual changes in space.

            Before we  begin talking about the odd effects of space on vision,

       we need to agree on some definitions.

            These are:

                VISUAL THRESHOLD: the minimum  amount  of light that elicits a

                                  sensation of light.

                VISUAL ACUITY   : the degree to which the details and contours

                                  of objects are perceived.

                                  Visual acuity is usually defined in terms of

                                  minimum resolvable separation.

            Threshold is a complex phenomenon, depending heavily on conditions

       within the eye and in the surrounding environment.  Conditions such

       as optical factors,  the state of the image forming mechanisms  of  the

       eye;retinal factors, such  as  the state of the cones; stimulus factors

       such as illumination, brightness of  the stimulus, contrast between the

       stimulus and the background, length of time exposed  to  the  stimulus,

       and so on; and other, random factors.

            Minimum separation is the shortest distance by which two lines can

       be separated and  still  be  perceived as two lines.  People with sharp

       vision can resolve lines which are  very  close  together.  People with

       less sharp vision must either move closer to the target (increasing the

       apparent separation), or move the lines farther apart  (increasing  the

       actual separation).

            Taken together,   these   two  measures  are  reasonably  accurate

       measures of the overall state of a persons vision.  It is said eyes are

       the windows into man's soul.  The  importance  of  the  organs of sight

       cannot be over-emphasized.  The visual system, eyes  and  brain,  are a

       navigation system which   can  measure  distance  through  stereoscopic

       vision, detect motion, focus from  the  tip  of  the  nose to infinity,

       recognize a multitude of colors, shades and shadows,  adapt  to  a wide

       range of lighting  conditions,  coordinate an average 70 kg male/female

       in motion as complex as a ballet or as exacting as threading a needle.

            It operates  through  a zillion  neural  interfaces  in  a  system

       thousands of times more powerful than the most advanced  computer,  and

       does it all  without  any  conscious thought at all.  You simply decide

       that you want to do thus and so, and it is done.

                                        Page 1

            For all  its  amazing versatility, vision is a specialized system.

       Human visual hardware is a result  of  a  billion  years  of  evolution

       within the earths atmosphere where light is scattered  by  molecules of

       air, moisture, and particulate matter.

            But as  we  ascend  into  our  atmosphere  light  distribution  is

       changed, due to the decreasing density  of  the  air. The visual system

       receives information differently.  Sometimes this can  result  in  odd,

       even astounding, visual effects.

            Gemini 4  astronaut Edward White reported seeing networks of roads

       during his space walk, and so did cosmonaut  Nikolayev from Vostok 3 as

       early as 1963.   "During the day, the earth has a predominantly  bluish

       cast.....I could detect  individual  houses  and  streets  in  the  low

       humidity and cloudless areas such as the Himalaya mountain area.  I saw

       a steam locomotive by seeing the smoke  first.....  I also saw the wake

       of a boat  on  a  large  river in the Burma-India area...and  a  bright

       orange light from  the  British  oil  refinery to the south of the city

       (Perth,Australia.)"

            The above observation was made  by Gordon Cooper in Faith 7 [1963]

       and it generated much skepticism in the light of the thesis  by Muckler

       and Narvan "Visual Surveillance and Reconnaissance from Space Vehicles"

       in which they  determined  that  a  visual angle of ten minutes was the

       operational minimum possible  for   humans,   and   that   the  minimum

       resolvable object length [M.R.O.L] at an altitude of 113 miles would be

       1730 ft.

            This limitation of acuity was revised the next year to 0.5 seconds

       of arc for  an  extended  contrasting line and 15 seconds  of  arc  for

       minimum separation of   two   points   sharply   contrasting  with  the

       background.

            So how could these astronauts  "see"  objects  much  smaller  than

       this?  The answer  is  that  the  eye isn't the entire  visual  system.

       There is a  mind  intimately  connected  with  the eye, and the mind is

       capable of inferring details where  none  can be seen.  Orbiting at 237

       miles in Skylab it was possible to see the entire east coast [Canada to

       the Florida Keys] and resolve details of a 500 feet  long  bridge based

       on inference.

            Of interest  is the fact that even though a mechanical eye [camera

       system] can resolve objects greater  than  fifty  times better than the

       human eye, without  human  ability  to  infer, people,  possessing  the

       ability to infer, can match that performance--or even surpass it.  That

       leads us to our first conclusion, the first observed difference between

       visual performance on  earth  and  visual  performance in space: Visual

       acuity in space exceeds that of earth  norm  when  objects  with linear

       extension such as roads, airfields, vessel wakes, etc.

            An ability called by some the "Search Light Effect".   This  is  a

       positive factor.  In space, vision is sharper than it is on the ground.

       The next factor  is not so positive.  In fact, it can be a grave danger

       to anyone working in the space environment.

            We judge distance by the mechanism  of  stereoscopic  vision.   It

       works by fusing the twin images impinging on the eyes,  combining  them

       into one image,  and producing a sense of distance.  This system relies

       on reference points.  One object overlaps another, or the images

                                        Page 2

       received in either eye are slightly different.

            You can  demonstrate  this  to  yourself  by simply looking into a

       mirror.  As you look, close one eye.  You see one side of your face

       slightly more than the other. Now look  through the other eye.  You see

       the other side  of your face.  Now, with both eyes open,  you  can  see

       your face and  somewhat  of  both  sides,  and  along  with that visual

       impression you have a sense of how far away you are from the image.

            The sides of your face, perceived  unequally  in  either  eye, are

       reference points for distance.  In space one has to deal with a poverty

       of reference points.  For  hardware  evolved  in  a reference  oriented

       paradigm this poses a grave problem, once out of the space craft gazing

       outward the eye  can  only  fix  on  the stars [without even a twinkle]

       which for all practical purpose is at infinity.

            This induces a state called "Empty  field  myopia".   Empty  Field

       Myopia is a condition in which the eyes, having nothing  in  the visual

       field upon which to focus, automatically focus at about 9 feet.

            An astronaut/cosmonaut experiencing empty field myopia focusing at

       9 feet would be unable see objects at a range as close as 100 feet.  If

       another spacecraft, satellite,  meteorite or whatever entered his field

       of vision, he or she would not be able  to determine either its size or

       its distance.

            That is our second conclusion: Vision in space is  very subject to

       a lack of visual reference points, a condition which induces a state of

       visual "neutral lock"   known  as  empty  field  myopia.   Is  there  a

       solution?  Man does not face any hostile  environment  in  his birthday

       suit, the clothing industry and walk-in-closets say it all.

            In space  we  will  wear  our exoskleton just as  we  wear  winter

       jackets in winter.   We  will  wear our helmets with visors to maintain

       our internal environment, filter out all those nasty rads etc.

            Since empty field myopia is a result  of loss of reference points,

       why not just build them into the visor itself?  Give the  eye points of

       reference.  Create a  virtual  reality?  This line of speculation leads

       to amazing concepts.

            To learn more about the concept  of virtual universe in the helmet

       read: Journal: Air & Space, [Smithsonian Publication]

             Article: Big Picture by Steven L.Thompson.

                      illustrated by Dale Glasgow.

            About the  creation of a virtual universe with new  computers  and

       software in the   helmets   of  F-16  fighter  pilots--this  is  not  a

       theoretical posibility but a reality.  There is another downside to the

       performance of human visual systems in space.

            One aspect of a adaptation to microgravity  [space sickness] is an

       increased dependence on visual as opposed to vestibular  mechanisms  in

       the stabilization of the retinal image during head movement.

            This phemonemon  only underscores the importance of being aware of

       our visual ability.  This is our third  conclusion:  Microgravitational

       effects on the human visual/orientation system can cause  unpleasant or

       even debilitating effects.

                                        Page 3

            As if  that  weren't  enough,  studies  done  by  the  Russians on

       cosmonauts on effects of perception  of  colors  in  space  suggests  a

       reduction in the  perception  of  brightness  of all colors.   Greatest

       degradation seems to occur in purple, azure, and green.

            Conclusion number  four: Visual perception of color is impaired in

       the space environment,  with implications  for  color  coded  reference

       systems.

            And, finally,  there  are  the light flashes.  Not  the  so-called

       fireflies noted in  orbital flights by astronauts [shown graphically in

       the movie "The Right Stuff"] but lights  perceived  as  faint  spots or

       flashes seen after  dark  adaptation  in  the  cabins   of  the  Apollo

       missions.

            These light  flashes  described  as  white  or colorless have been

       classified as three types:

             1)  Described as "spots" or "starlike"  objects 66 % of the time.

                 Appearing in both eyes simultaneously or one eye at a time.

             2)  Described as "streaks" 25 % of the time.

             3)  Described as "lightning discharge seen behind  clouds" 9 % of

                 the time.

            It is  of  interest that the very same astronaut who reported them

       in the Apollo flights failed to see  them  in  previous Gemini flights.

       After the Apollo flights this phenomena was noted by  the  crew  of all

       three Skylab missions  especially  when they crossed the South Atlantic

       Anomaly.

            W.Zachary Osborne,  Ph.D., and  Lawrence  Pinsky,  Ph.D.,  at  the

       University of Houston  &  J.Vernon  Bailey at Lyndon B.  Johnson  Space

       Center conducted an  investigation of this phenomena and concluded that

       it was due to heavy cosmic radiation penetrating the craft.

            The fact that the effect was noted  only  after the eyes were dark

       adapted confirmed retinal  interaction  rather  than  interaction  with

       optic nerve.

            Which brings  us  to  our last conslusion: Radiational effects and

       light flashes, can be a problem to future space travelers.

            These are not the only effects  that we will (literally) see as we

       explore and move  out  into  space.  They are, however,  a  significant

       divergence from normal  human vision, and must be taken into account in

       both the planning and execution of  future  construction workers living

       and working in space, and it must be taken into account.

            Failure to do so can be costly, both in terms  of  time  lost  and

       valuable equipment damaged or destroyed.  It can also be fatal.  To the

       construction worker who fails to see a moving object coming toward him.

       To the pilot   that  misjudges  an  approach,  or  to  anyone  in  that

       environment relying on vision for safety.

                                        Page 4

            These are the effects: Unusual visual acuity

                                   Empty field myopia

                                   Space sickness

                                   Lost color perception

                                   Light flashes

       They must be  taken  into  account during the planning and execution of

       any space mission.  Failure to do so can be costly...or fatal.

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                                        FINIS

                                        Page 5