Space stations, especially the most recent ISS, were designed to keep the astronauts as comfortable as possible—the ISS modules are roomy, bright, and kept at a constant 70 degrees Fahrenheit. It is important that the crew members are comfortable because they are kept busy all their waking hours. In a typical day, crew members will spend twelve hours working, two exercising, two preparing and eating meals, and eight hours sleeping.
Despite the amenities provided, life in space reqiures considerable acclimation. Once on board a space station, the first order of business for novice astronauts is to become accustomed to the weightless environment, adjust to living in close quarters, and master new technologies necessary for carrying out routine daily activities. These three conditions, unique to all space stations, mean that the most basic and commonplace daily activities require rigorous attention, patience, and coordination.
The first sensation experienced by three-quarters of all astronauts in weightlessness is space adaptation syndrome, more commonly known as space sickness. It is a form of motion sickness that occurs in spaceflights when astronauts are free to move about in the weightless environment. The syndrome did not occur on the lunar module or on early orbital flights because the astronauts were firmly strapped into small capsules.
Symptoms of space adaptation syndrome vary from one person to another but may include nausea, vomiting, anorexia, headache, malaise, drowsiness, lethargy, paleness, and sweating. The sickness is believed to be caused by sensory conflicts within and between the vestibular system—a collection of sensitive organs in the inner ear that maintain balance and orientation—and the visual system. Space physicians believe that when astronauts float and spin in a weightless environment, what their eyes see and what their vestibular organs sense lead to a neural mismatch that upsets the nervous system.
As intense as the symptoms can be, space sickness is usually of short duration, lasting from one to three days. Fortunately for astronauts, once they experience it, it never reoccurs. Unfortunately for them, however, although the sickness disappears relatively quickly, astronauts report that floating vomit is one of the least pleasant aspects of the first few days in space. When vomit is projected into the cabin, suction devices are deployed to capture and contain it.
Physicians have been able to reduce the occurrence of space sickness by employing countermeasures that include medications, head movement exercises to accelerate the process of adaptation, head restraints, and adjusting the vestibular system to weightlessness through biofeedback training.
Space sickness usually involves a dramatic loss of appetite, but eventually the astronaut begins eating again. When that happens, there are many challenges for the first-time visitor to the ISS. Meals on space stations present myriad problems because of weightlessness, a shortage of storage space, spoilage,
Ed Lu, the American commander on the ISS, enjoyed working on the space station as well as eating on it. While in space on the ISS, he wrote an article about food titled "Eating at Café ISS" for NASA's Web site. In the article, he describes some of the more interesting and amusing experiences of dining in a weightless environment.
We don't have a real kitchen up here, but we do have a kitchen table. You might wonder of what use a table is if you can't set anything down on it, but we have bungee straps and Velcro on the tabletop so you can keep your food containers, spoon, napkins, etc. from floating away. You can find Yuri [a Soviet cosmonaut] and I around the table 3 times a day. In fact the table, which is located in the Service Module, is kind of the social center of the ISS. Even though we only have 2 crew members now, it is where we congregate when we have time off. Of course there are no chairs around the table, what we do is float around the table while we prepare our meals and eat. There are a couple of handrails on the floor to slide your feet under to stabilize yourself.
As for utensils, the only utensil we use is a spoon. All of the food that requires a utensil to eat has some sort of sauce or at least some moisture to it, so it naturally sticks to the spoon. This is the same effect on the ground that allows drops of water to stick to windows, here it allows us to eat without having our food fly all over the place. This force isn't very strong, so you have to move fairly slowly when eating, or the food will literally fly right off your spoon and onto the wall.
The Russian drink packets are clear plastic and have a simple one-way valve where you add water; while the other side of the packets has a built in straw. The design is ingenious; you just cut off one end of the packet with scissors to open up the valve, slide the packet onto the water tap, turn on the water, mix well, and then use the scissors on the other end to open up the straw. The problem is that if you aren't careful, they have a tendency to leak and it is easy to get juice or tea all over yourself or the walls. The same property of liquids that lets them stick to your spoon also makes liquids stick to your face.
Much of the Russian-supplied food comes in cans. One of the advantages of cans is that if it is just for a short while, you can just let the can float as long as you are careful to keep an eye on where it is going. Remember that you don't have to worry about food spilling out of the can if it turns upside down!
and a shortage of water needed for food preparation. In spite of these obstacles to good food, astronauts look forward to meals more than any other daily routine.
Most foods are dehydrated to conserve space and are packed into compartments and freezers in the upper section and wardroom. Water, one of the most precious commodities, is particularly problematic since it cannot be compressed. It is also one of the heaviest commodities. As a result, equipment has been designed to capture and recycle water from exhaled air and even from urine.
All food is initially prepared, cooked, and packaged on Earth. Food is processed in a way that makes it stick to a spoon and keeps it from crumbling into hundreds of particles that could float away. Thick foods such as sauces, pastes, oils, peanut butter, and moist cake batter are used to bind dry, flaky foods together. Some foods are also selected for their natural ability to hold together. Tortillas, for example, are preferred to slices of bread because they create far fewer crumbs. Floating bread crumbs are more than a minor annoyance. On Skylab, astronauts complained about bread crumbs floating around the interior and getting stuck in filters or in their eyes.
To make food keep as long as possible, most of what is prepared for the ISS is freeze-dried, low-moisture, or thermostabilized—meaning that it has been heated to kill bacteria—and then sealed in airtight packages. To prepare them for consumption, foods require very little preparation. Even many beverages are packaged in a dehydrated form and then are slightly hydrated before they are consumed. The ISS's galley, like many kitchens on Earth, is equipped with water, microwave ovens, and refrigerators, allowing everyone on board to access more normal types of fresh food, including fruits, vegetables, and even ice cream.
Nutritionists ensure that the food astronauts eat provides them with a balanced supply of vitamins and minerals. Meals are eaten three times a day, but because astronauts expend less energy working in a weightless environment than they would on Earth, their caloric requirements are considerably lower than they would otherwise be. Calorie requirements differ from one astronaut to another. For instance, a small woman would require only about nineteen hundred calories a day whereas a large man would require about thirty-two hundred calories.
On board the ISS, more than one hundred food items are available to astronauts; half are provided by American nutritionists and half by their Russian counterparts. This is done to provide a fair mix of the foods from the two different cultures. American favorites are meatloaf and turkey with mashed potatoes and gravy, spaghetti, a variety of soups, brownies, peanut butter, and even ice cream. From the Russian chefs, favorites are a thick cabbage and beet soup called borscht; a selection of pickled meats; baursaki , which are small fried doughnuts made from unleavened dough; and kazakh , which are meat-flavored noodles.
There are many other types of foods an astronaut can choose from, such as fruits, nuts, chicken, beef, seafood, candy, and drinks, including coffee, tea, orange juice, fruit punch, and lemonade. Condiments are provided such as ketchup, mustard, and mayonnaise. Salt and pepper are available, but only in a liquid form because in orbit astronauts cannot sprinkle salt and pepper on their food; it would simply float away.
Some foods, such as brownies and fruit, can be eaten in their natural form. Other foods require adding water, such as macaroni and cheese or spaghetti. Some packaging, such as plastic tubes filled with mashed potatoes and gravy and soft ice cream, prevent food from flying away because they are sucked from holes at one end of the tubes. The food packaging is designed to be flexible, easier to use, and to maximize space when stowing or disposing of food containers.
Just as calorie requirements are lower in orbit than on Earth, so too are sleep requirements less. When the time for sleep does come, weightlessness somewhat simplifies the process of bedding down. Since humans cannot sense an "up" or "down" in a weightless environment, they can sleep in any position. Since space is in short supply, designers of space station interiors can position astronauts to sleep vertically or horizontally. On the ISS, sleep compartments provide space for four people. The first person sleeps on the top bunk, the second on the lower bunk. A third person sleeps on the underside of the lower bunk, actually facing the floor. A fourth person sleeps vertically, attached to a wall with Velcro straps. Because the astronauts are in a weightless environment, mattresses are not needed. Instead, each bed consists of a padded board with a fireproof sleeping bag attached to it. Astronauts zip themselves inside the sleeping bags, generally leaving their arms out. Crew quarters also provide each astronaut with an individual light, communications station, fan, sound-suppression blanket, and sheets with weightlessness restraints for those who find the sleeping bags too warm. Pillows are available as well.
Sleep can be difficult to find from time to time. Much like on Earth, astronauts report waking up in
At no time are all crew members allowed to sleep at the same time; someone must always be awake to handle potential emergencies. Ground controllers actually decide when individual crew members go to bed. When it is time to wake up, the ground control sends wake-up music or a call to the crew. On America's Skylab, ground control picked a song for an astronaut each day. Sometimes a family member will request that controllers play a favorite song for their particular loved one on the ISS. In other cases, depending on the astronaut's own tastes, ground control may play rock and roll, country and western, or classical music. However, most of the time the wake-up call is unnecessary since most space station crew members use an alarm clock just as they might on Earth.
No matter what sleep schedule a crew member adheres to, exercise is a critical part of the daily routine. Treadmills and ergometers, more commonly called stationary bikes, are used extensively by astronauts to maintain fitness. Such equipment has been used in space since Skylab in the 1970s, although they tend to cause a good deal of vibration. This can disrupt sensitive experiments elsewhere in the spacecraft, making sophisticated shock absorption systems necessary. Resistive exercise, a newer option to workouts, eliminates the vibration issue. Astronauts stress their bones and muscles by working against a resistive force, usually by pulling against strong bungee cords. Less motion is involved, and so there is very little vibration.
Strenuous exercise is vital for the heart. Over time, the astronaut's body responds to weightlessness by decreasing the amount of blood. Without regular strenuous exercise, an astronaut's heart will shrink, as it only has to pump this smaller volume of blood. This condition creates problems once an astronaut returns to Earth, when the heart must once again pull blood up to the brain against the force of gravity.
Just as important to keeping fit is keeping clean. At the same time, sanitation is more difficult to maintain within the confines of a space station than on Earth. Studies conducted on early space station flights revealed that the populations of some microbes can increase rapidly under the combination of weightlessness and the confined spaces of an orbiting space station. The consequence is that many infectious diseases can easily spread to everyone aboard a space station. This is of particular concern since access to medical personnel is limited at best and pharmaceuticals are in short supply.
To prevent the growth of microorganisms, the eating utensils, dining area, toilet, and sleeping facilities in a space station are regularly cleaned. All potential sources of contamination must be carefully isolated. Since there is no washing machine aboard, soiled articles of clothing are sealed in plastic bags. Garbage and trash are also sealed in plastic bags, as are all food containers and used eating utensils, all of which is returned to Earth for laboratory analysis before it is either recycled or destroyed.
Each crew member has his or her own personal hygiene kit, which contains items such as a razor, shaving cream, hand cream, toothpaste, a toothbrush, a comb, nail clippers, deodorant, and other personal items, just as one might have on Earth. However, simple tasks like brushing teeth can be challenging in a weightless environment. The water that one would ordinarily use to wash out one's
Astronauts on the ISS work six and a half days per week. Each day is carefully planned to optimize time for all needed activities, and the only relief from long days is a half day each Saturday.
Astronauts wake up at 7:00 Greenwich Mean Time, which is 2 A . M . in Houston and 11 A . M . in Moscow. Astronauts cannot rely on the usual daylight and nighttime cycles because in orbit and traveling seventeen thousand miles per hour, crew members experience sixteen sunrises and sunsets each day. Because of this rapid orbit rate, everyone must cover windows or wear masks to sleep.
After rising, the next order of business is using the bathroom and washing up. If all suction devices for the toilet and washbasin are working properly, astronauts finish in fifteen minutes and move to the breakfast area for the simplest and shortest of the day's three meals. If the suction plumbing is not working, someone may spend the remainder of the day fixing it, a common problem. At 8 A . M . sharp, the daily planning conference begins that involves a conference call with ground control centers in Houston and Moscow to review the plan for the day and answer any questions. Following that, everyone gets started on the day's work.
The work assignments vary week to week for each astronaut, but each will spend about twelve hours a day performing some experiment or part of an experiment. On the ISS, the most common work investigates how metal alloys crystallize as they cool in the weightless environment. Another major task involves work on plasma crystals, which are microscopic plastic spheres with electrical charges that repel each other and in the process form a regular lattice structure not found on Earth.
After work, or interspersed with experiments, each astronaut has certain housekeeping responsibilities scheduled. These are things like cleaning filters, performing periodic inspections of the emergency equipment, testing the water supply, and vacuuming out the air ducts.
Twice during the day—once in the morning and once in the late afternoon—each member completes a one-hour exercise program. After sweating on the treadmill or bike, they wash using towelettes impregnated with no-rinse soap or shampoo. At about 7 P . M . the second conference with Houston and Moscow is held to review the results of the day, after which dinner is eaten, the favorite activity of the day. Following dinner, each astronaut has a couple of hours of free time to send and read e-mails from home, take photographs out the window, listen to music, and write entries in personal journals. Finally, around 10 or 11 P . M ., it is time for bed.
mouth cannot simply be spit out to drain away; any that escapes during brushing floats around in midair. To deal with this, astronauts use a freshwater hose followed by a vacuum hose to suction off the used water.
Although brushing teeth is a relatively simple task, other hygiene tasks prove time consuming and complicated under weightless conditions. Commonplace activities on Earth, such as shaving and hair cutting, for example, are slow, tedious processes because they must be done inside a plastic tent equipped with a vacuum device to suction away loose hair and whiskers. Escaped bits of hair are more than just unsightly. Any hair or whiskers floating about can lodge in sensitive electronic equipment, causing it to malfunction. Given the problems such activities present, most astronauts choose to avoid shaving and haircuts for as long as possible.
Some aspects of personal care, such as keeping clean, are not optional. In Skylab, astronauts actually showered using an enclosed shower stall. The stall was a cylinder with a collapsible fireproof canvas shower curtain for sides and a metal ring to secure it to the floor. When not in use, the whole assembly was collapsed and stored on the floor. To use the shower, astronauts would step inside the ring on the floor, raise the canvas curtain on a hoop, and attach it to the ceiling. Each astronaut was provided a ration of three gallons of water dispersed from a flexible hose with a push-button shower nozzle. The used water was contained within the stall and was vacuumed from the shower enclosure into a bag and then deposited in the waste tank. On the ISS, however, astronauts prefer quick sponge baths using washcloths or moistened towelettes.
Although the complexity of bathing sometimes acts as a deterrent to personal grooming, using the toilet is an even more complicated task—and one that cannot be avoided. The toilet on all space stations
Not all hazards and inconveniences of space travel are as mundane and mechanical as using the bathroom and brushing one's teeth. In orbit, astronauts are exposed to radiation to a much greater extent than on Earth, where the atmosphere provides a shield for all living things. Of particular concern is the radiation emitted by the Sun, especially during periods when massive flares erupt from the Sun's surface. The radiation released during these massive
To explore and work in space, astronauts must take their environment with them because there is no atmospheric pressure and no oxygen to sustain life outside of their craft. Inside the spacecraft, the atmosphere can be controlled so that special clothing is not needed, but when outside, humans need the protection of a space suit.
The $12-million space suits used for space walks on Skylab and the International Space Station are a modular design so complex that users require an assistant to help put them on. The lower module, called the Lower Torso Assembly (LTA), roughly the equivalent of pants and boots, consists of a waist module, trousers module, and boots. The pieces are made of fabric but are joined together using metal bearing rings. The term fabric is really an understatement for the material, however. It contains a layer of urethane-coated nylon, followed by Dacron, neoprene-coated nylon, five layers of aluminized Mylar, and an outside layer of Teflon, Kevlar, and Nomex. Collectively, these many layers control internal temperature and protect the body against micrometeorite strikes that otherwise would easily penetrate the suit, causing a loss of pressure and oxygen, and pass through the astronaut's body, possibly causing death.
The counterpart to the LTA is the Hard Upper Torso (HUT), which is made of fiberglass and connects the arm module, glove module, and helmet module. The Primary Life Support System (PLSS) attaches to the back of the HUT. It resembles a backpack and provides the astronaut with oxygen and battery packs. The PLSS also controls the air pressure in the suit as well as the temperature of the oxygen and water that run through the garment to keep the astronaut cool. The HUT removes humidity, odors, and carbon dioxide from the air inside the suit and also carries the communication equipment and a multitude of sensors. A secondary oxygen pack attaches to the bottom of the PLSS for emergency oxygen and other life support functions. On the front of the HUT, astronauts carry a Display and Control Module, which keeps them informed about the status of the PLSS.
Apollo space helmets are formed from high-strength polycarbonate and Kevlar and are attached to the space suit by a pressure-sealing neck ring. Unlike earlier helmets, which were closely fitted and moved with the crew member's head, the Skylab helmet is fixed and the head is free to move within it. While walking in space, astronauts wear an outer visor assembly over the polycarbonate helmet to shield against eye-damaging ultraviolet radiation and to maintain head and face thermal comfort.
explosions passes through delicate human tissue and can damage cells.
The primary risk to astronauts comes in the form of an increased likelihood of cancer. Dr. Francis Cucinotta, director of Space Radiation Health at NASA's Johnson Space Center in Houston, says, "Younger women are particularly vulnerable to cell and tissue damage from space radiation. The greatest threat is an increased chance of developing breast, ovarian or uterine cancer." 16 Dr. Cucinotta adds that men's bodies overall are less sensitive to radiation, but even so, a forty-five-year-old male astronaut will only be allowed by NASA to spend a total of about 250 days in space. A clear understanding of the threat has not yet been achieved, however. According to physicians writing for the European Space Agency, "The long-term effects of space radiation on the human body . . . are still totally unknown." 17 This view is echoed by Dr. Paul Todd, chairman of the American Society for Gravitational and Space Biology, who adds, "This is not an easily solved scientific problem." 18
Concerns over potential overexposure to radiation become even more acute when astronauts leave the shielded environment of their space stations and venture outside. For a variety of reasons, space walks, referred to by aerospace personnel as extravehicular activities (EVAs), are necessary. Such activities as attaching new modules, repairing equipment, and replacing worn-out parts all require some EVAs. ISS planners anticipate that the assembly of all modules will require about fourteen hundred hours of EVAs and about the same number over the lifetime of the ISS for a variety of repairs and adjustments.
Prior to departing the craft, astronauts don their pressurized space suits, which can sustain them for up to six hours at a time. Aboard the ISS, space suits have gloves with fingertip warmers for better dexterity, radios with multiple channels for communications, helmet-mounted floodlights and spotlights, internal controls for heat and cooling, and new multilayer fabrics to protect against extreme temperatures, ultraviolet radiation, and even micrometeorites. During an EVA, the weightless environment is a distinct advantage since each fully equipped space suit weighs 220 pounds on Earth.
Prior to departure, astronauts suit up in an airlock, which is a compartment that is sealed off from the space station. Then, all air is pumped out, which accomplishes two important objectives. First, it allows the astronauts to adjust to gas mixture differences in their space suits. Second, they gradually adjust to the change from the atmospheric pressure maintained in the space station to the dramatically lower pressure of space. After about forty minutes, the hatch is opened to the outside, the astronauts clip on a nylon cord that acts as a tether, and they begin their EVA. Against the possibility that the tether could become accidentally detached, NASA engineers developed a jet-powered backpack that allows free-floating crew members to fly back to the station.
EVAs are not undertaken without good reason, nor are they done without careful preparation. According to ISS astronaut Don Pettit, "Nothing happens fast. It takes several days to prepare for a space walk. Small details are important. We clean our visors and spread a thin layer of anti-fog on the inside surface. If there is too much anti-fog it can make your eyes sting and water; too little and it will fog up. It has to be just right if you want to see anything." 19
Once in space, astronauts must move slowly using hand and toe holds welded to the exterior. Movement is slow because the bulky space suit contains hundreds of wires and cords that could snag or tangle. A space walk is no time to take chances, and when things go wrong, EVAs are sometimes aborted. Astronaut Jerry M. Linenger explains that each arm and leg movement during an EVA requires a great deal of thought and planning. There are plenty of hazards, and a single mistake could be catastrophic:
A tear big enough to expose you to the full vacuum of space would be one of the most painful deaths imaginable. All the air would be sucked from your lungs. Blood would feel as if it was boiling in your veins, and your internal organs would go into seizure. A space walker must keep tethered to his spacecraft. There are no second chances. 20
The thirty-year history of space stations has clearly established the viability of humans living and working in orbit. Dozens of astronauts living successfully in space for a total of thousands of days have laid a foundation for continued research on life in space. What at one time was a topic of conjecture has been conclusively and decisively answered by experimentation. During the 1970s physicians specializing in space medicine also set out to establish whether the human body could successfully function in a weightless environment. With that objective and others in mind, hundreds of medical experiments have revealed some interesting results.