One of the earliest designs for living in space was clearly a fantasy: an orbiting sphere, 200 feet (61 meters) in diameter, made of 12 million bricks and housing thirty-seven human inhabitants determined to create an ideal society. It was described by Boston religious leader Edward Everett Hale in a short story titled "The Brick Moon" in Atlantic Monthly magazine in 1869. It was written as a fable, never meant to be taken seriously. Later, Russian mathematician Konstantin Tsiolkovsky, after seeing France's Eiffel Tower in 1895, was at first obsessed with the idea of building a tower 35,786 kilometers (22,300 miles) into the sky. In his 1920 novel, Beyond the Planet Earth, a more mature Tsiolkovsky proposed a geosynchronous orbiting space station, with an international crew, greenhouses, and solar power—a remarkable vision very close to modern reality.
The First Space Stations
More than eighty years later, with the experiences of the Salyut, Skylab, and the Mir space station, along with the space shuttle behind us, we no longer have to speculate about life in space—we have firsthand knowledge. Astronauts staying in space for extended periods have had to settle for very modest accommodations, often living in cramped, oversized aluminum cans. These "human habitation modules," as they are called, are designed to be rugged, lightweight (hence the aluminum), and functional, but they do not take the human factors of comfort and privacy into account. Skylab housed three astronauts in an aluminum cylinder—essentially one section of a Saturn IVB booster rocket—that was 48 feet (14.6 meters) long and 22 feet (6.7 meters) in diameter for missions lasting as long as 84 days.
In the early stages of the International Space Station (ISS), crews of three astronauts used the Zvezda (the Russian word for "star") module for living quarters. This cylindrical module—originally developed for the Mir 2 station—is 43 feet (13.1 meters) long, and has sleeping quarters for two people; the third person sleeps in a Temporary Sleep Station (TeSS) located in the science laboratory. Zvezda has the necessary toilet and hygiene facilities, a kitchen with a refrigerator and freezer, a table for meals, and a tread-mill and a stationary bike for exercise.
NASA's plans for a U.S.-built habitation module have gone through many revisions over the years as budgets for space exploration have been cut back. A habitation module capable of housing up to seven astronauts has recently been scrapped due to cost overruns. For now, Zvezda is the only habitation module available on the ISS.
Future Habitat Designs
In the future, with permanent space stations , space hotels, and long voyages to Mars a distinct possibility, larger living quarters will be needed. Tourists staying in a hotel on the Moon will surely require entertainment facilities, luxurious accommodations, privacy, and room to move around. Astronauts on long voyages will need some privacy to escape the constant presence of coworkers, and they will require more comfort than is available in the oversized aluminum cans. But designers have been limited to payloads that can be carried by the shuttle, which has severely restricted the size of possible habitation modules.
Engineers at the NASA Johnson Space Center in Houston, Texas, came up with a solution to the problem in 1997. The proposed "TransHab" (for transit habitat) module is an inflatable living space made of lightweight, flexible materials stronger than steel. TransHab could be folded during transportation in the shuttle and inflated to its natural size when deployed in space. Like a balloon, the inflated size will be much larger than its collapsed size; living spaces three times bigger than the current aluminum modules will be possible. Using strong, lightweight materials keeps the payload weight down, so the shuttle can carry it. Instead of living inside of a can, astronauts would live in a balloon.
In its current design, TransHab will be a four-level pressurized cylinder with a foot-thick (0.3 meters) outer shell consisting of about two dozen layers of varying materials. Layers of an insulating ceramic material combined with layers of polyurethane foam will protect TransHab from meteors or other space debris by absorbing energy and shattering the particle before it causes extensive damage. Kevlar®, the material used in bullet-proof vests, will provide structural support. Three bladders of a polymer material will hold in the air, and a fireproof cloth will line the interior walls.
The internal core of TransHab will be made of lightweight carbon-fiber composite materials. The floors and walls will fold out after TransHab is inflated; in some areas, floor panels can be opened as passageways to create a vaulted-ceiling effect. A central passageway will provide access to all four levels of the module. The wardroom and galley area on the first level will have a kitchen with a refrigerator and freezer, a microwave oven, a water dispenser, and a table for twelve that will be used for meals and meetings. An "Earth-viewing" window will provide a scenic area for diners. The crew quarters on the second level will have six individual compartments with 81 cubic feet of space each, so every astronaut will have a private living/ sleeping room with a sleeping bag, a computer entertainment center, and storage space for personal items. A mechanical room containing the environmental control and life support systems will encircle the crew quarters. Level three is the crew health care area, with a treadmill, an exercise bicycle, another "Earth-viewing" window, a "space bath" for "showering," and a medical exam room complete with emergency equipment and medical supplies. The fourth level is just a pressurized tunnel to connect TransHab to a space station.
With its roomy living space and provisions for entertainment, exercise, and privacy, TransHab could find many uses beyond the ISS. It could be the perfect vehicle for transporting a crew of astronauts during the long voyage to Mars. Once there, TransHab could transform into a "mobile home" for astronauts while they explore the red planet. Larger units with even more room and luxurious accommodations could become the first hotels in space, whether sitting on the surface of the Moon or floating in orbit at L2, one of the five Lagrangian points in the Earth-Sun system where the gravitational forces balance to provide a stable orbiting location.
Clearly, other types of space habitats are possible, and ideas previously unimagined will emerge. Perhaps huge, environmentally controlled geodesic domes on the Moon or Mars could act as giant greenhouses where humans could live and grow crops for consumption. Rotating cylindrical or ring-shaped spacecraft could produce centrifugal forces that simulate gravity for the space tourist. Concept proposals have been developed for a space hotel orbiting 775 miles (1,247 kilometers) above Earth, with a tether connected to a space dock only 160 miles (257 kilometers) above Earth. Passengers would fly to the space dock in a reusable launch vehicle, then ride a space elevator up to the hotel. Maybe Tsiolkovsky's tower idea was not so farfetched after all.
see also Biosphere (volume 3); Closed Ecosystems (volume 3); Communities in Space (volume 4); Domed Cities (volume 4); Dyson Spheres (volume 4); Dyson, Freeman John (volume 4); Hotels (volume 4); Human Factors (volume 3); Human Spaceflight Program (volume 1); L-5 Colonies (volume 4); Life Support (volume 3); Lunar Bases (volume 4); O'neill Colonies (volume 4); O'neill, Gerard K. (volume 4); Settlements (volume 4); Space Elevators (vollume 4); Transhab (volume 4); Tsiolkovsky, Konstantin (volume 3).
Stine, G. Harry. Handbook for Space Colonists. New York: Holt, Rinehart, and Winston, 1985.
Spacefarers. Alexandria, VA: Time-Life Books, 1990.
NASA web site on TransHab. <http://spaceflight.nasa.gov/station/assembly/elements/transhab/>.