Modest Beginnings Salyut and Skylab

The Soviets won the race to place the first space station in orbit. On April 19, 1971, they launched Salyut 1. Two years later, on May 14, 1973, America responded by launching Skylab. Both space stations shared the modest objectives of studying the effects of long-duration spaceflight on the human body, photographing Earth and the rest of the solar system, and preparing the way for a dramatically improved next generation of space stations. Everyone involved in these projects had much to learn. Engineers building Salyut and Skylab shared concerns about size, shape, weight, and strength. Protection from micrometeors, insulation from extreme temperatures, and how to attach many of the external components also consumed engineers from both nations.

Other teams focusing on the interior of space stations had concerns about how astronauts would live and perform their experiments. The interior space had to be designed to accommodate as many as three astronauts, along with supplies of food, water, and oxygen to last for many months. The interior space also had to accommodate occupants' need for sleep, exercise, hygiene, and personal privacy—this in addition to space for conducting several experiments involving a variety of scientific devices. Still others worked to solve problems involving the generation of electricity, keeping the interior spaces clean and safe, and taking into account unique problems that working in a weightless environment presented.

The Architecture of Space Stations

The architecture of both Salyut and Skylab were similar in that they both consisted of a single large cylinder within which crews lived and performed their experiments. Orbiting Earth at roughly 250 miles in space, these laboratories required relatively little structural reinforcement because their orbits placed them in a vacuum where pressure was negligible. Furthermore, although the craft would orbit Earth at about 17,000 miles per hour, there would be no friction of atmosphere to tear away external equipment. Secondary components necessary for sustaining the crew and supporting their scientific activities, therefore, were attached to the exterior surface of the spacecraft. As a result, both Skylab and Salyut would be anything but streamlined.

Other alterations to the basic cylindrical shape were also necessary. For example, a device known as a multiple docking adapter was needed that would firmly lock transport vehicles in place. To allow crew members to exit and reenter for space walks, technically called extravehicular activities, an airlock module, capable of accommodating one crew member at a time, was attached. Each space station would carry one or more externally mounted telescopes, to be used for photographing the Sun and other objects in the solar system. Externally mounted antennae would receive and send radio signals. And to provide the stations with electricity, multiple solar panels would reach outward. On Skylab, the four solar panels, each forty-eight feet long, would collectively look like the blades of an old-fashioned windmill.

Although both space stations were bulky and relatively heavy, one focus of their design was compactness. Both Salyut and Skylab were assembled on Earth, tightly packed into the cargo bay of a single rocket, and then blasted into orbit. To accomplish this feat, parts of the space stations were folded before insertion into the cargo bays. Then, when they were released in space, the folded parts were meant to unfold. Space aboard the launch vehicle was, therefore, at a premium. As a consequence neither the United States nor the Soviet Union sent crews on the rockets carrying the space stations. Instead, it was expected that crews would be sent once all components had safely deployed and the stations had stabilized in their respective orbits.

Optimizing Internal Space

Engineers realized that the space station envisioned was far too large to place in orbit with the boosters then available. Therefore, the interiors of Skylab as well as Salyut were designed to optimize precious usable space. The tons of scientific equipment, food, water, and personal effects of the crews meant that every cubic millimeter of space would be needed. Years prior to launch, when engineers were still designing the stations, they sketched to scale every item that would go aloft to ensure that it would actually fit. Since astronauts in a weightless environment occupy all three dimensions of a room as they float from place to place, artists familiar with human anatomy were employed to sketch in astronauts to ensure they would have adequate room to maneuver. Engineers also weighed every item to within the accuracy of one gram to verify that the fully loaded space station would not be too heavy for the rocket to lift it to the proper orbit.

Skylab, with an overall length of 118 feet and a diameter of 22 feet, had an interior volume of roughly 10,000 cubic feet, the equivalent of a small house. Divided into two stories, Skylab was designed for a work laboratory on the upper story, which occupied 38 percent of the interior, with the larger lower story for living quarters. This lower story was subdivided into a wardroom (used for dining and exercise), sleeping compartments, and an enclosure housing a shower/toilet.

Since interior space was at a premium, creative approaches to its use were encouraged. For example, aboard Skylab all tables and many other horizontal surfaces were designed to be folded up against the walls when not in use to make room for larger experimental apparatuses. Even the shower facility folded up. To conserve space, clothing for all astronauts was vacuum sealed, compressed, and stowed in special containers.

Engineering for Weightlesness

No anticipated condition occupied more time and required more engineering considerations than that of weightlessness. In designing interiors, engineers had to take into account that everything not secured in some way would be floating. In such an environment,

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