A quick spray of Windex is not necessary to get a clear view of this situation. There is a growing need for windows for space travelers, whether they are making suborbital jumps, staying in Earth’s orbit, or taking distant trips to the Moon and beyond. Flash back decades ago, when the first Mercury space capsule offered a small porthole for its single-seat occupant, Alan Shepard. Similarly, the first human in space, cosmonaut Yuri Gagarin, only had a small window to enjoy the view. Interestingly, in those early years of pioneering space travel, no one knew what microgravity would do to the human eye and a person’s vision. We’re talking floats! Apart from that, space tourism has meant an evolution of safe and solid windows and has addressed the engineering challenges of producing them. But what is the future of space travelers? You might like Astronaut Alan Shepard inspects his Mercury capsule after ocean recovery in 1961. Notice how small the vehicle’s viewing window is. (Image credit: NASA) Earth Observation “Based on my experience interviewing professional and commercial astronauts, I would say that windows are key to the ‘Overview Effect’ experience,” said Frank White, who coined the phrase and is author of “The Overview Effect: Space Exploration and Human Evolution” (Houghton Mifflin Harcourt, 1987). White drew attention to the profound shift in cognitive awareness that most space travelers experience when observing our planet from Earth’s orbit and beyond. It’s clear that for NASA astronauts, the transition from space shuttle missions to the International Space Station (ISS) was critical to having a more meaningful opportunity to see Earth from a distance, White said. “This change was intensified with the arrival of the ISS dome, where astronauts spend a large amount of time ‘Earth-watching,'” he told Space.com. Best room with a view in the house: An astronaut looks out from the dome of the International Space Station. (Image credit: NASA)Customer experienceWhite said that because Virgin Galactic and Blue Origin have focused on their suborbital space tourism customers experiencing the overview effect, “both companies have guaranteed great views from the windows of their spacecraft. As a result, commercial astronauts have had profound experiences, even though they are weightless and look at Earth only briefly.” What to read next It’s no coincidence that SpaceX installed a special “dome” on its Crew Dragon capsule for the Inspiration4 astronaut mission in September 2021, and it paid off, White noted. Anyone who doubts this fact, he said, should watch the video of the Inspiration4 crew’s unveiling of that window. “The story goes that the Mercury flight engineers didn’t want the spacecraft to have windows,” White said. “The astronauts persisted and ultimately prevailed. Fortunately, their precedent continues to this day, to the benefit of the astronauts and the people of Earth. The overall effect is one of the most important ‘byproducts’ of space exploration.” Blue Origin’s New Shepard suborbital vehicle offers large windows to maximize customer experience. (Image credit: Blue Origin) Human Comfort Something similar comes into view is Samuel Coniglio IV, author of “Creature Comforts in Space: Designing Enjoyment and Sustainability for Off-World Living” (BookBaby, 2024). Coniglio also points to that scene from the 1983 movie “The Right Stuff,” in which the original Mercury astronauts argued with engineers about the need to see outside their capsule. After all, they were a group of elite pilots and may have needed to take manual control of their ship at some point. “Just as plants and showers play a critical role in human comfort, so do windows,” Coniglio said. “Being able to see the vast skies allows you to become one with the universe and see all the interesting things happening outside. We can’t just live in a box; we also need to be part of the outside world.” Size matters: A window on Blue Origin’s New Shepard rover, compared to that of a NASA Mercury space capsule from the 1960s. (Image credit: Blue Origin) Structural Reliability Lynda Estes is the discipline leader for spacecraft transparencies at NASA’s Johnson Space Center in Houston. She is an engineering expert who has been integrating windows into crewed spacecraft for decades. Estes has worked on many vehicles during his NASA career: the space shuttles, the International Space Station, the Orion capsule of the Artemis program, and all of the private, human-rated spacecraft developed by companies associated with the agency’s Commercial Crew Program. Estes is an internationally sought-after resource for the design, development, engineering, testing and operations of high-risk human-rated pressure cabins in both aviation and spaceflight. She is the author of NASA’s current requirements document that ensures high structural reliability in spacecraft glass window designs. Starting out as a stress analyst for mechanisms, “windows are a whole new PhD,” Estes told Space.com. “Glass is a brittle material. It breaks. That’s what it likes to do. But it’s also wonderfully transparent.” A view of Earth from NASA’s Orion spacecraft during the Artemis II mission around the Moon in April 2026. (Image credit: NASA) Room with a view In previous NASA programs, windows were made of multiple panes of different types of glass. For example, the European-built dome on the ISS, which offers the “best room with a view”, consists of six trapezoidal side windows and a circular top window. Each window consists of four panels for protection against astronaut-induced scratches as well as external impacts caused by space debris. The entire window can be replaced, or individual panes that are scratched or filled with debris. Resetting a full window requires a “big, fancy ballet,” Estes said, one that’s well choreographed, in which an astronaut first places an external pressure cover over the window during a spacewalk. Generally, the ISS dome serves as an observation and work area when the crew operates the station’s robotic arms or observes visiting vehicles. But it is also an attraction during free time, offering astronauts extraordinary views of the Earth and celestial objects. Static fatigueBut glass also has worrying characteristics. On the one hand, small defects affect its strength. And glass actually loses structural capacity over time, according to Estes. “We call that static fatigue,” he said, referring to cracks that grow microscopically under a load. “We’re working hard to eliminate glass because of those two features,” Estes said, explaining that NASA wants to move to an all-acrylic window design for the Orion spacecraft. “Acrylic, when looking at re-entry temperatures, acts as a heat shield.” As a structural engineer, Estes warns that windows are a concern. “We come from, How do we keep everyone alive? Cutting a hole in the side of your pressure vessel and installing something like glass to replace that hole is a really bad choice,” Estes said. “That’s why we’re trying to get contractors and our partners to go with acrylic. It’s a much more structurally stable material.” Purchasing RiskOne of the challenges of glass is that it produces shards when broken. “And the first place those fragments want to go is the human body that just approached the window to see what happened,” Estes said. With glass you buy risk, Estes said. On the other hand, NASA has a written requirement, he said: “If you’re going to put humans inside and send it to space, it has to have a window.” Estes and his team are now providing guidance for spacecraft windows to be used in future lunar operations, including human landing systems for the Artemis program. Back here on Earth, do you clean the windows at home? “I don’t,” Estes responded.
