The View from Above: The Gemini Visual Acuity Experiments

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The View from Above: The Gemini Visual Acuity Experiments

Astronauts L. Gordon Cooper Jr. and Charles “Pete” Conrad Jr. (shown here) participated in visual experiments during the Gemini V mission in August 1965.

Credits:

NASA/L. Gordon Cooper Jr.

NASA astronaut L. Gordon Cooper, Jr. took 29 color photographs of the Earth with a 70mm camera as he orbited our planet during the Mercury-Atlas 9 mission in May 1963. Cooper’s view from the window of his Faith 7 spacecraft was spectacular, and he reported that he could see vehicles motoring on dirt roads, smoke-belching trains, and the tops of houses.

Researchers and members of the public had their doubts. Could Cooper actually see objects on the Earth’s surface in such fine detail while orbiting 100 miles above the planet? Some vision experts assumed that astronauts with 20/20 vision could not clearly see objects with sides less than 150 feet long at orbital altitudes. Although Cooper reportedly had exceptional 20/12 vision, certainly he could not see a white automobile kicking up a dust cloud near the U.S.-Mexico border as he claimed. Cooper, however, was not alone in his assertions. Other Mercury astronauts also reported seeing objects on the Earth in striking detail.

During his 22-orbit Mercury-Atlas 9 spaceflight in May 1963, L. Gordon Cooper Jr. took photos from the Faith 7 spacecraft including this one showing lakes in Western Tibet.NASA

These claims caused mental health professionals to question the sanity of NASA’s first astronauts. A story in Air Force and Space Digest noted that some psychiatrists speculated that “weightlessness was causing the astronauts to hallucinate and that the space program was in for serious trouble.” While mental health experts considered the effects of space flight on the brain, visual acuity experts mulled over the Mercury astronauts’ assertions and developed an experiment to determine what they could see on Earth from space.

Putting Astronaut Vision to the Test

NASA and its partners developed two visual acuity experiments and conducted them during the crewed Gemini V and Gemini VII missions.  The first experiment involved looking through an optical device reminiscent of binoculars. Test subjects looked through the eyepieces to see an assortment of rectangles in various positions and levels of contrast.  They were then asked to identify the directional orientation of the rectangles. 

Another part of the experiment involved creating two enormous terrestrial eye charts composed of gigantic white rectangles. The rectangles, created by the Dow Chemical Corporation, ranged in size from roughly 150 to 600 feet long. The experiment team placed one set of rectangles on dark tilled soil in Laredo, Texas and another near Carnarvon, Australia, and asked Gemini V and VII astronauts to identify their directional orientation from orbit. This visual acuity tool was nicknamed the “Eye-Q” chart.

In-Flight Vision Testing InstrumentDrawing illustrating a Gemini astronaut using the In-Flight Vision Tester.NASA

Gemini V Visual Acuity ExperimentThis illustration shows the intended orientation of the Gemini spacecraft as it orbited over the “Eye-Q” ground observation sites.NASA

Cloudy conditions, sunlight scattered by the window of the Gemini spacecraft, and unfavorable orbital orientations during overflight all impacted the astronauts’ views of the ground-based experiments. Nevertheless, during some orbital revolutions, astronauts on both missions were able to see portions of the ground site near Laredo.

Aerial view of the visual acuity experiment’s ground site in Laredo, Texas.NASA

Their reports on the Laredo “Eye-Q” site, combined with the results of the binocular-like vision tester experiments conducted before, during, and after the flight, revealed that astronauts could in fact see roads and ships with following wakes from orbit. The experiments also determined that an astronaut’s vision did not deteriorate during a two-week spaceflight.1

Astronaut Frank Borman, Gemini VII command pilot, participates in a vision experiment using the in-flight visual acuity device during the two-week mission in December 1965.NASA

Implications

Determining what features on Earth astronauts could accurately see from orbit was about much more than sanity checking astronaut reports. Understanding what human eyes could see from space, as well as seeing the photographs taken on NASA’s early crewed missions had huge implications for geologists, geographers, oceanographers, and others studying our planet.