About Space Stations - Living and Working in Space
What is a space station?
Space stations are platforms for long-term living and working in space that orbit Earth; in the future, they may orbit other planets or moons. Space stations are places to carry out scientific research, such as observing crystal growth in microgravity, in an environment not found on Earth. Some of this research — like the development of semiconductors and pharmaceuticals — may have commercial applications. Space stations allow scientists and engineers to test materials and designs for future space travel. The Russians launched the first space station, Salyut 1, in 1971. Several other platforms have been put into space for varying lengths of time. Today, the United States operates the space shuttle, a vehicle capable of orbiting Earth for periods up to two weeks. The International Space Station is almost completed and will provide a permanent — and international — human presence in space.
What is needed to live and work on a space station?
A space station is a “home away from home.” It must provide everything that is necessary to live for the duration of time that the astronauts will be occupying the station for a particular mission. Some necessities, such as food, equipment, and research materials, can be replenished when the station is revisited by shuttles. However, shuttle visits are spaced weeks to months apart, so astronaut crews and mission control personnel check carefully to make sure all needed materials and supplies are available — there are no Wal-Marts in space (yet)!
Atmosphere Control — Astronauts need to breathe air that is similar in composition to Earth's (78% nitrogen, 21% oxygen, and 1% other gases). Oxygen and nitrogen are supplied to the International Space Station during shuttle flights. Eventually, the station will have the technology for oxygen to be made onboard by splitting water into its separate parts of oxygen and hydrogen. While we breathe nitrogen and oxygen, we exhale carbon dioxide. It would be dangerous to allow this to build up in the station's atmosphere. Carbon dioxide is filtered from the atmosphere and released to space.
Temperature Control — The station is well insulated from the extreme cold of space. The onboard equipment generates enough heat to warm the station. In fact, the heat produced by equipment will overheat the station. Excess heat is vented off into space.
Water — Water has to be provided to the station by shuttle flights. This is a costly provision and so water is carefully conserved — there are no long, hot showers in space! Eventually, recycling and purifying systems will recapture water from daily washing, moisture in the air from breathing, moisture from the heating and cooling systems onboard the station, and water from urine. This recycling will reduce, but not eliminate, the need for water to be provided from Earth.
Light/Electrical Power — Electricity to run the equipment and to provide light is provided by eight large solar arrays that transform solar energy into power. During each 90-minute orbit, the station is in sunlight for 45 minutes and darkness for 45 minutes. While in darkness, power comes from batteries that are recharged during periods of sunlight.
Food — All food is provided from Earth. Eventually, some food will be grown on the station. Some plant growth experiments have been conducted in space but a practical food growth system does not yet exist.
Waste Removal — Just as on Earth, living and working in space creates waste. Some of that waste — like water waste — will eventually be recycled and reused. Efforts are made to create as little waste as possible. For example, nuts are shelled before they are packaged for the station, and much of the food is dehydrated. Ultimately, all waste goes back to Earth; only water is vented into space (from other missions, not from the space station). Solid human waste is compacted, dehydrated, and stored for removal. Similarly, other trash is collected, compacted, and stowed away for later removal to Earth.
Communications — Astronauts talk to Mission Control and send electronic mail by radio using satellites to relay the messages. Inside the station there are intercoms and telephones.
What do astronauts do on space stations?
One thing they are doing right now on the International Space Station is building the station! As materials and modules are shuttled to the station, the astronauts put them into place and make sure all systems are working. Space stations also are ideal for launch, repair, and retrieving of satellites. The space shuttle was used for several missions to access, repair, and upgrade the Hubble Space Telescope. Astronauts also conduct scientific experiments in space.
In addition to their work, astronauts have their daily routines of eating, sleeping, bathing, and exercising. Most of the food that they eat is frozen or dehydrated; they simply add water if needed, and microwave it for a hot space meal. Astronauts are given the chance to determine what they want to eat months before they go into space — as long as they choose nutritionally sound meals! Sleeping has its own challenges — imagine slipping into a sleeping bag that is attached to the wall. Bathing is not routine, either. Instead of a shower, the astronauts take sponge baths to conserve water. Exercise is crucial to staying healthy in space because, without it, astronauts lose bone and muscle mass. The most common forms of daily exercise include bicycling and running on a treadmill — strapped in place, of course. Finally, astronauts need a little time off to read, e-mail friends and family, play games, or just look out the window.
What kind of research can be done on a space station?
On Earth, gravity influences the way crystals, plants, and animals grow. In contrast, space stations offer an environment where there is very little gravity. Research will be conducted to understand how weightlessness influences growth and development. In microgravity nearly perfect crystals can be grown; it may be possible to use these to create new and more efficient drugs and microchips for computers. Research will also concentrate on how plants can be grown in space to provide food. Studies will assess how weightlessness influences calcium and tissue loss in humans — and how this can be prevented. Perhaps the most important reason for living in space is to determine how to keep humans healthy for the length of time that will be required by journeys of exploration to Mars and other planets.
Other research will encompass monitoring our Earth's atmosphere, weather, climate, oceans, land, and resources. The space stations offer “the best seat in the house” to make observations of Earth's environments. Like the Hubble Space Telescope, space stations are above Earth's light pollution and atmosphere, so they also have a clearer view of the stars and planets; extensive astronomy studies can be undertaken.
What challenges are there to living and working in space?
One of the primary challenges to living and working in space is the “weightless” environment. Under reduced gravity conditions, there is very little “load” on bones and muscles, so living organisms lose bone mass, muscle tissue, and fluids. Even the heart — a muscle — loses mass because it does not have to work as hard. Humans in space must exercise to maintain their bone and tissue mass so that they can return to Earth's gravity and function well.
In space there is no protective atmosphere as there is on Earth. Humans must have shielding to protect them from solar radiation, which can damage tissue. The space station offers some protection. While astronauts are working outside the station, they work in the protection of a space suit. However, the astronauts are still exposed to more radiation than they would be on Earth. NASA has set limits for the amount of radiation an astronaut can be exposed to and monitors how much exposure each astronaut has received.
Living and working in space can be grueling. There is considerable stress to get all the work accomplished, and unforeseen issues pop up constantly. The astronauts may get lonely for home on long missions. And living in tight quarters with the same small group of people can get on anyone's nerves! When astronauts are being selected for missions, the mission planners are looking for people who will do well in these conditions. Other mechanisms are implemented as well; leisure time is important and built into the schedule, contact with families and friends is maintained, and there are plenty of the comforts of home, including movies, books, music, and games.
What stations have been constructed in space?
Salyut (Russian) — On April 19, 1971, the USSR launched Salyut 1, the world's first space station. Two months later, a crew of three successfully docked with Salyut. By today's standards, Salyut was small — 20 meters long, 4 meters across, with an area of about 100 square meters — but certainly big enough to be called a space station. Inside, there was a vegetable garden where astronauts grew Chinese cabbage and onions using aquaculture. The two cylindrical working compartments housed a dining area, recreation area, toilet, seven control stations, food and water storage, exercise equipment, and scientific equipment. There were six successful Salyut stations that flew from 1973 to 1985. The longest mission lasted for 185 days, and one of the stations (Salyut 7) hosted nine crews who totaled over 800 days at the station.
Skylab (U.S.) — America's first experimental space station, Skylab, was designed for long-duration flights. Skylab had two objectives: (1) to prove that humans could live and work in space for extended periods, and (2) to expand our knowledge of solar astronomy beyond Earth-based observations. Successful in all respects despite early mechanical difficulties, three three-man crews occupied Skylab for a total of 171 days in 1973 and 1974. It was the site of nearly 300 scientific and technical experiments, medical experiments on humans' adaptability to microgravity, solar observations, and detailed Earth-resource experiments. The empty Skylab returned to Earth on July 11, 1979, burning up in the atmosphere and scattering debris over the Indian Ocean and the sparsely settled region of Western Australia.
Mir (Russian) — Mir, which means “peace” in Russian, was launched in 1986 as a new-generation space station and successor to Salyut. With its kitchen and gym, Mir offered its crew a more comfortable environment in which to conduct their experiments than Salyut. One crew clocked 366 days on Mir, which was manned almost continually by Russian crews for 12 years. The Shuttle-Mir program brought several American astronauts to live and work onboard Mir in preparation for life onboard the International Space Station. After 15 years of service, Mir returned to Earth and intentionally burned up over the Pacific Ocean.
International Space Station (16 countries involved) — The International Space Station (ISS) is the single largest international aerospace project ever undertaken, involving the United States, Canada, the 10 members of the European Space Agency, the United Kingdom, Japan, Russia, and Brazil. Its assembly will take over 40 flights of the space shuttle and Russian spacecraft and will involve complex in-orbit operations and hardware/software integration tasks that are unprecedented in space history. The station, slated to be completed this decade, is 360 feet across and 290 feet long. It travels at 17,500 miles (28,163 kilometers) per hour, orbiting Earth once every 90 minutes at a distance of 250 miles (400 kilometers) above the surface. The mission of the ISS is to enable long-term exploration of space and create a permanent orbiting science institute that provides a laboratory free of the effects of gravity where scientists can conduct long-term research in material, life, and medical science. The low-gravity environment unmasks the basic properties of materials, which will lead to new manufacturing processes and products to benefit mankind. It provides a unique space platform for observing Earth and space, improving our understanding of Earth's environment and the universe. Finally, the ISS provides the foundation for the future exploration and development of space. It allows scientists to study long-term effects of weightlessness on the human body for application to future human space exploration. It will allow technology research in fluids, combustion, life support systems, and radiation environment, which is needed for future human exploration of space.
May 27, 2009