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.

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.

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.

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

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.

The scientific community’s interest in the recollections and photographs of the Earth’s surface as seen by the Mercury and Gemini astronauts motivated NASA and its partners to advocate for new Earth-observing instruments. NASA, the U.S. Geological Survey, the Office of Naval Research, and the U.S. Department of Agriculture noted that surface images of the Earth captured from above could be used to inventory crops, map geological features, monitor natural disasters, and better understand the ocean’s processes.

The promise of these real-world applications motivated the creation of the Earth Resources Technology Satellite (ERTS), later renamed Landsat 1. Launched by NASA in 1972, the data from Landsat 1’s camera and multi-spectral scanner were used along with data from the agency’s Earth Resources Aircraft Program to monitor the oceans, agricultural fields, natural disaster sites, and more.

In the six decades since America’s first pioneering human spaceflights, NASA has continued to observe the Earth from orbit, aircraft, and even ground level in a continuing quest to help solve problems here on Earth.

Note

[1] In subsequent years, scientists have documented that roughly 70% of astronauts experience Spaceflight Associated Neuro-ocular Syndrome (SANS) during longer spaceflights.

Many of NASA’s most important aerospace breakthroughs that began in the laboratory were ultimately proven in the sky. For decades, experts at NASA’s Glenn Research Center in Cleveland conducted flight tests — piloting aircraft into targeted environments such as icing clouds and carefully defined atmospheric routes. This approach allowed them to collect measurements directly in flight, providing critical data that linked laboratory theories to practical performance. 

The center’s flight research dates to the 1940s, when NASA Glenn was known as the Aircraft Engine Research Laboratory for the National Advisory Committee for Aeronautics, NASA’s predecessor agency. During World War II, engineers and pilots worked to improve aircraft performance and increase high-altitude reliability. In the mid-to-late-1940s, flight research helped make early jet and ramjet engines practical. Later, Glenn’s flight programs helped improve the efficiency and environmental performance of aircraft engines — primarily conventional jet engines. 

Behind those early flight programs was a pioneering group of pilots who helped establish NASA Glenn’s reputation for airborne research. The center’s first generation of pilots, including Howard Lilly, Joseph Walker, William Swann, and William “Ed” Gough, helped lay the groundwork for more than two dozen other Glenn pilots, including future astronauts Neil A. Armstrong and Fred Haise. 

Together with Glenn’s researchers, engineers, and support staff, these pilots established airborne research capabilities that NASA continues to rely on today. Their work demonstrated how flight testing could bridge the gap between laboratory research and real-world performance. 

“These missions transformed aircraft into flying laboratories,” said Mark Russell, a NASA safety officer and pilot who served as the former acting chief of Aircraft Operations at Glenn. “They bridged the gap between ground testing and full-scale flight, proving the measurements needed to connect theory with performance. The testing also helped validate technologies and procedures later used aboard spacecraft and orbital missions.” 

Research workhorses 

From the start, NASA put its aircraft to work on a wide range of research challenges. 

For decades, NASA Glenn aircraft have been used to study in-flight icing hazards, collecting data that has helped make commercial aviation safer. For nearly 40 years, NASA Glenn’s De Havilland DHC-6 Twin Otter served as the center’s workhorse for icing research, gathering data that helped shape modern aviation safety standards. 

Beyond improving aviation safety, Glenn’s flight research also explored new propulsion technologies that could transform the future of flight. Today, researchers are exploring hydrogen as an aviation fuel. But NASA Glenn helped show its potential viability decades ago using its Martin B-57B Canberra aircraft. After developing a hydrogen fuel system for the B-57B, a team tested it safely from February to April 1957. The flights showed the system’s reliable operation and advanced efficiency, marking a major milestone in aviation technology.  

Flight testing also supported technologies destined for use beyond Earth, helping researchers evaluate hardware under conditions that closely resembled space. Beginning in 1963, the center began a program to test and measure how well solar cells worked under conditions similar to those in space. Using specially modified airplanes, including Learjets, NASA conducted flights to help recreate some of the sunlight and atmospheric conditions that solar cells would experience outside Earth’s atmosphere. The program lasted decades, supporting space technology calibration through numerous high-altitude flights and adapting to newer aircraft over time. 

Researchers later applied these airborne capabilities to environmental science, extending their value beyond aviation and space technology. Using the Twin Otter and S-3B Viking over the Great Lakes, researchers tracked harmful algal blooms on Lake Erie by measuring changes in water color and composition. The data improved satellite systems used to monitor water quality and ecosystem health.  

Glenn’s research aircraft also played an important role in preparing technologies and experiments for spaceflight through microgravity testing. NASA Glenn advanced microgravity research through in-flight testing using specially modified aircraft, such as its DC-9, to create short periods of weightlessness during parabolic maneuvers. These flights allowed researchers to study how fluids, combustion, materials, and experimental equipment behaved in near-zero gravity before experiments were conducted in space.  

Recent breakthroughs 

Other significant accomplishments enabled by Glenn’s flight research include supporting the development and testing of sustainable aviation technologies, including research related to more fuel-efficient engines and sustainable aviation fuels, and advancing in-flight instrumentation and measurement techniques used across aeronautics research. 

In 2024, Glenn’s Flight Operations participated in an optical communications study using the center’s Pilatus PC-12 NG aircraft. This mission successfully demonstrated the ability to transmit large volumes of data through a laser communication system across NASA’s legacy infrastructure. The work contributed to NASA’s broader effort to advance optical communications for future missions. NASA further tested optical communications on the Artemis II mission and effectively transmitted substantial amounts of data from the Orion capsule to multiple ground stations over the course of the 10-day journey.  

As NASA’s flight research enterprise evolved, the agency also restructured how it manages its research aircraft. In October 2025, NASA streamlined its aircraft flight operations, relocating its aircraft from Glenn to NASA’s Armstrong Flight Research Center in Edwards, California. NASA Glenn continues its important icing and propulsion research and communications technology development in collaboration with Armstrong.  

From its historical roots in wartime engine development to modern work on aircraft safety, Glenn’s airborne research has consistently moved innovative ideas from the laboratory to real-world application. For more than eight decades, NASA Glenn has transformed ideas first proven in the laboratory into innovations validated in the sky — a legacy that continues to shape the future of aviation and space exploration.