Imagine going camping for over a week with several of your close friends. You would make sure you have plenty of food and the gear to cook and eat it with. The food would have to be stored properly and nonperishable to avoid spoilage. After finishing your meal, or at the end of your camping trip, you would then stow all your gear and dispose of your trash properly just before the ride home.

Astronauts basically do the same thing when they go to space. Preparation varies with the food type. Some foods can be eaten in their natural form, such as brownies and fruit. Other foods require adding water, such as macaroni and cheese or spaghetti. Of course, an oven is provided in the space shuttle and the space station to heat foods to the proper temperature. There are no refrigerators in space, so space food must be stored and prepared properly to avoid spoilage, especially on longer missions.

Click an image for more space food descriptions.

Condiments are provided such as ketchup, mustard and mayonnaise. Salt and pepper are available but only in a liquid form. This is because astronauts can't sprinkle salt and pepper on their food in space. The salt and pepper would simply float away. There is a danger they could clog air vents, contaminate equipment or get stuck in an astronaut's eyes, mouth or nose.

Astronauts eat three meals a day - breakfast, lunch and dinner. Nutritionists ensure the food they eat provides them with a balanced supply of vitamins and minerals. Calorie requirements differ for astronauts. For instance, a small woman would require only about 1,900 calories a day, while a large man would require about 3,200 calories. There are also many types of foods an astronaut can choose from such as fruits, nuts, peanut butter, chicken, beef, seafood, candy, brownies, etc... Drinks range from coffee, tea, orange juice, fruit punches and lemonade.

Click an image for more space food descriptions.

As on Earth, space food comes in packages that must be disposed. Astronauts must throw their packages away in a trash compactor inside the space shuttle when they are done eating. Some packaging actually prevents food from flying away. The food packaging is designed to be flexible, easier to use, as well as maximize space when stowing or disposing food containers. Exercise in Space: Use It or Lose It http://www.nasa.gov/audience/forstudents/5-8/features/F_Your_Body_in_Space.html

08.05.04 Besides eating and sleeping, what do astronauts spend more time doing in space than anything else? It's exercise.

Image to right: Astronaut Peggy A. Whitson exercises on the Space Station in 2002. Credit: NASA

Exercise is the number one health priority in space, said Don Hagan, director of exercise physiology at Johnson Space Center. "No other activity except eating and sleeping is given that much priority. Two and a half hours each day are devoted to fitness."

Why is it so important for astronauts to exercise while they're in space? If astronauts don't exercise, their bodies start losing bone and muscle. Bone and muscle loss mean decreased size and strength, and can reduce an astronaut's ability to do work because it makes them weak.

Weakened astronauts would be less able to do tasks while in space, Hagan says. Also, if there were an emergency, the astronauts would need to be in good shape to get out of the Space Shuttle or Space Station quickly. Once they land on Earth, weakened muscles and bones would make walking difficult. Muscle can be built back up with therapy. But lost bone is not as easy to get back.

Image to left: Astronaut Robert L. Curbeam works out on the ergometer on the Space Shuttle Atlantis in 2001. Credit: NASA

In microgravity, body fluids are moved around. Fluids such as plasma are lost throughout the body. Plasma is where red blood cells live. Less plasma means there is less blood to carry oxygen to the rest of the body. Exercise, however, has been shown to increase the amount of plasma in the body. Astronauts who exercise make more red blood cells.

Microgravity also brings about another change in something called "orthostatic intolerance," Hagan said. "When you lie down, stand up quickly, and feel light-headed, that's orthostatic intolerance," he said. "Your body tries to stop this from happening. It does so by increasing its heart rate and blood pressure to keep more blood returning to your heart. If you can't do that, you'll pass out. With no gravity and less blood volume, astronauts are more prone to fainting. Again, exercise can help increase blood volume and circulation. That helps prevent fainting. Three Main Exercises

In space, astronauts use three pieces of exercise equipment. Each piece does something different. The exercise equipment is put on raised platforms to reduce the noise the machines make.

1. Cycle Ergometer: This is like a bicycle, and the main activity is pedaling. It is used to measure fitness in space because it's easy to check heart rate and how much work is being done. 2.

Image to right: Astronaut Ed Lu uses the RED equipment on the Space Station in 2003. Credit: NASA

3. Treadmill: Walking or jogging on the treadmill is like walking on Earth. Walking is the single most important way to keep bones and muscles healthy. Because the lack of gravity tends to make people float, harnesses are attached to the astronauts to hold them to the walking surface.

4. Resistance Exercise Device (RED): The RED looks like weight-lifting machines you may see on television. To use it, astronauts pull and twist stretchy rubber-band-like cords attached to pulleys. The RED can be used for a total body workout. From squats and bending exercises for the legs, to arm exercises and heel raises, astronauts can do them all on the RED.

Russians and Americans have different exercise routines on the Space Station. But they all have the same goal: keeping the astronauts and cosmonauts healthy. Breathing Easy on the Space Station

A Science@NASA story by Patrick L. Barry

Life support systems on the ISS provide oxygen, absorb carbon dioxide, and manage vaporous emissions from the astronauts themselves. It's all part of breathing easy in our new home in space.

November 13, 2000 -- Many of us stuck on Earth wish we could join (at least temporarily) the Expedition One crew aboard the International Space Station (ISS). Floating effortlessly from module to module, looking down on Earth from a breathtaking height of 350 kilometers.... An artist's rendering of the ISS as it It's a dream come true for innumerable space lovers. currently appears. But be careful what you wish for! Living on the Space Station also means hard work, cramped quarters, and... what's that smell? Probably more outgassing from a scientific experiment or, worse yet, a crewmate.

With 3 to 7 people sharing a small enclosed volume on the still-growing Space Station, air management is critical.

Life support systems on the ISS must not only supply oxygen and remove carbon dioxide from the cabin's atmosphere, but also prevent gases like ammonia and acetone, which people emit in small quantities, from accumulating. Vaporous chemicals from science experiments are a potential hazard, too, if they combine in unforeseen ways with other elements in the air supply.

So, while air in space is undeniably rare, managing it is no small problem for ISS life support engineers.

In this second article in a series about the practical challenges of living in space, Science@NASA examines how the ISS will provide its residents with the breath of life.

Making Oxygen From Water

Most people can survive only a couple of minutes without oxygen, and low concentrations of oxygen can cause fatigue and blackouts.

To ensure the safety of the crew, the ISS will have redundant supplies of that essential gas.

"The primary source of oxygen will be water electrolysis, followed by O2 in a pressurized storage tank," said Jay Perry, an aerospace engineer at NASA's Marshall Space Flight Center working on the Environmental Control and Life Support Systems (ECLSS) project. ECLSS engineers at Marshall, at the Johnson Space Center and elsewhere are developing, improving and testing primary life support systems for the ISS. The Expedition One crew -- Bill Shepherd, Most of the station's oxygen will come from a process called "electrolysis," which uses Sergei Krikalev and electricity from the ISS solar panels to split water into hydrogen gas and oxygen gas. Yuri Gidzenko -- aboard the Space Each molecule of water contains two hydrogen atoms and one oxygen atom. Running a Station. During their current through water causes these atoms to separate and recombine as gaseous four-month stay, the hydrogen (H2) and oxygen (O2). crew will relied on the station's hardware to provide breathable air. The oxygen that people breathe on Earth also comes from the splitting of water, but it's not a mechanical process. Plants, algae, cyanobacteria and phytoplankton all split water molecules as part of photosynthesis -- the process that converts sunlight, carbon dioxide and water into sugars for food. The hydrogen is used for making sugars, and the oxygen is released into the atmosphere.

"Eventually, it would be great if we could use plants to (produce oxygen) for us," said Monsi Roman, chief microbiologist for the ECLSS project at MSFC. "The byproduct of plants doing this for us is food."

However, "the chemical-mechanical systems are much more compact, less labor intensive, and more reliable than a plant-based system," Perry noted. "A plant-based life support system design is presently at the basic research and demonstration stage of maturity and there are a myriad of challenges that must be overcome to make it viable."

Breathing with Machines

Hydrogen that's leftover from splitting water will be vented into space, at least at first. NASA engineers have left room in the ECLSS hardware racks for a machine that combines the hydrogen with excess carbon dioxide from the air in a chemical reaction that produces water and methane. The water would help replace the water used to make oxygen, and the methane would be vented to space. The oxygen that humans and "We're looking to close the loop completely, where everything will be animals breathe on Earth is (re)used," Roman said. Various uses for the methane are being considered, produced by plants and other including expelling it to help provide the thrust necessary to maintain the photosynthetic organisms such as Space Station's orbit. algae.

At present, "all of the venting that goes overboard is designed to be non-propulsive," Perry said.

The ISS will also have large tanks of compressed oxygen mounted on the outside of the airlock module. These tanks will be the primary supply of oxygen for the U.S. segment of the ISS until the main life support systems arrive with Node 3 in 2005. After that, the tanks will serve as a backup oxygen supply.

Last week, while the crew were waiting for activation of a water electrolysis machine on the Zvezda Service Module, they breathed oxygen from "perchlorate candles," which produce O2 via chemical reactions inside a metal canister.

"You've got a metallic canister with this material (perchlorate) packed inside it," Perry explained. "They shove this canister into a reactor and then pull an igniter pin. Once the reaction starts, it continues to burn until it's all used." Each canister releases enough oxygen for one person for one day." "It's really the same technology that's used in commercial aircraft," he continued. "When the oxygen mask drops down, they say to yank on it, which actuates the igniter pin. That's why you have to give it a tug to begin the flow of oxygen."

Keeping the Air "Clean"

At present, carbon dioxide is removed from the air by a machine on the Zvezda Service Module based on a material called "zeolite," which acts as a molecular sieve, according to Jim Knox, a carbon dioxide control specialist at MSFC.

The removed CO2 will be vented to space. Engineers are also thinking of ways to recycle the gas.

In addition to exhaled CO2, people also emit small amounts of other gases. Methane and carbon dioxide are produced in the intestines, and ammonia is created by the breakdown of urea in sweat. People also emit acetone, methyl alcohol and carbon monoxide -- which are byproducts of metabolism -- in their urine and their breath.

Activated charcoal filters are the primary method for removing these chemicals from the air. Maintaining a healthy atmosphere is made even more complex by the dozens of chemicals that will be used in the science experiments on board the ISS.

This diagram shows the flow of recyclable resources in the Space Station's Environmental Control and Life Support System (ECLSS). After a long day at work, there is nothing like a good night's sleep! Just like on Earth, a worker in space goes to bed at night then wakes up the next day and prepares for work all over again. There are a few differences, though.

In space there is no up or down and there is no gravity. As a result, astronauts are weightless and can sleep in any orientation. However, they have to attach themselves to a wall, a seat or a bunk bed inside the crew cabin so they don't float around and bump into something.

Click an image to see how astronauts sleep.

Space shuttle and space station crews usually sleep in sleeping bags. On the space shuttle, astronauts can also sleep in the commander's seat, the pilot's seat or in bunk beds. There are only four bunk beds in the space shuttle. So that means on missions with five or more astronauts, the other crewmembers have to sleep in a sleeping bag attached to their seats or to a wall.

On the space station there are two small crew cabins. Each one is just big enough for one person. Inside both crew cabins is a sleeping bag and a large window to look out in space. Currently, space station crews have three astronauts living and working in space for months at a time. Where does the third astronaut sleep? If it's okay with the commander, the astronaut can sleep anywhere in the space station so long as they attach themselves to something.

Expedition Two Commander Yury Usachev and Flight Engineer James Voss slept in the crew quarters inside the Zvezda Service Module. Flight Engineer Susan Helms slept inside the Destiny Laboratory.

Astronaut Susan Helms slept in the huge Destiny Laboratory Module by herself while she was living aboard the International Space Station. This is on the opposite side of the station from the Service Module where her crewmates slept. The length of the International Space Station during that mission was 52 meters (171 feet) long.

Generally, astronauts are scheduled for eight hours of sleep at the end of each mission day. Like on Earth, though, they may wake up in the middle of their sleep period to use the toilet, or stay up late and look out the window. During their sleep period, astronauts have reported having dreams and nightmares. Some have even reported snoring in space!

The excitement of being in space and motion sickness can disrupt an astronaut's sleep pattern. Sleeping in close quarters can also be disruptive since crewmembers can easily hear each other. Sleeping in the shuttle's cockpit can also be difficult since the Sun rises every 90 minutes during a mission. The sunlight and warmth entering the cockpit window is enough to disturb a sleeper who is not wearing a sleep mask.

When it is time to wake up, the Mission Control Center in Houston, Texas, sends wake up music to the crew. Usually, Mission Control will pick a song for a different astronaut each day. Sometimes a family member will request a favorite song for their particular loved one. Depending on the astronaut, Mission Control will play all types of music such as rock and roll, country and western, classical, or Russian music. However, only a shuttle crew receives wake up music while a space station crew uses an alarm clock. Water on the Space Station A Science@NASA story by Patrick L. Barry and Tony Phillip

Rationing and recycling will be an essential part of life on the International Space Station. In this article, Science@NASA explores where the crew will get their water and how they will (re)use it.

November 2, 2000 -- Future astronauts poised to blast off for an extended stay on the International Space Station (ISS) might first consider dashing to the restroom for a quick splash at the lavatory, or better yet, a luxurious hot shower. Once on board the ISS, spacefarers are in for a steady diet of sponge baths using water distilled from -- among other places -- their crewmates breath.

If you're squeamish, read no farther, because the crew will eventually include lab rodents -- and they'll be breathing, too. All of the denizens of the space station lose water when they exhale or sweat. Such vapors add to the ambient cabin humidity, which is eventually condensed and returned to the general water supply.

Sometimes it's better not to think about where your next glass of water is coming from!

Rationing and recycling will be an essential part of daily life on the ISS. In orbit, where Earth's natural life support system is missing, the Space Station itself has to provide abundant power, clean water, and breathable air at the right temperature and humidity -- 24 hours a day, 7 days a week, indefinitely. Nothing can go to waste.

In this article, the first of a series about the practical challenges of living in space, Science@NASA will examine how the Space Station's Environmental Control and Life Support System (ECLSS), under continuing development at the Marshall Space Flight Center, will help astronauts use and re-use their precious supplies of water. Future installments will explore air management, thermal control and fire suppression -- in short, all of the things that will make the Space Station comfortable and safe.

Making a Splash in Space

Before recycling can begin, there has to be some water to start with.

"We have plenty of water on the Space Station now," says Jim Reuter, leader of the ECLSS group at the Marshall Space Flight Center. "The Russian module Zarya is packed with contingency water containers (CWCs) that were carried over from the Space Shuttle during assembly missions earlier this year. They look like duffle bags and each one holds about 90 lbs.

The ECLSS Water Recycling System (WRS), developed at the MSFC, will reclaim waste waters from the Space Shuttle's fuel cells, from urine, from oral hygiene and hand washing, and by condensing humidity from the air. Without such careful recycling 40,000 pounds per year of water from Earth would be required to resupply a minimum of four crewmembers for the life of the station.

Not even research animals are excused from the program.

Shuttle pilot Terry Wilcutt with 7 contingency water containers destined for the space station Mir. "Lab animals on the ISS breath and urinate, too, and we plan to reclaim their waste products along with the crew's. A full complement of 72 rats would equal about one human in terms of water reclamation," says Layne Carter, a water-processing specialist at the MSFC.

It might sound disgusting, but water leaving the space station's purification machines will be cleaner than what most of us drink on Earth.

"The water that we generate is much cleaner than anything you'll ever get out of any tap in the United States," says Carter. "We certainly do a much more aggressive treatment process (than municipal waste water treatment plants). We have practically ultra-pure water by the time our water's finished."

Mimicking Mother Earth

On Earth, water that passes through animals' bodies is made fresh again by natural processes. Microbes in the soil break down urea and convert it to a form that plants can absorb and When water evaporates from the ocean and surface waters, it use to build new plant tissue. The granular soil leaves behind impurities. In the absence of air pollution, also acts as a physical filter. Bits of clay cling to nearly pure water falls back to the ground as precipitation. nutrients in urine electrostatically, purifying the water and providing nutrients for plants.

Water excreted by animals also evaporates into the atmosphere and rains back down to the Earth as fresh water -- a natural form of distillation.

Water purification machines on the ISS partly mimic these processes, but they do not rely on microbes or any other living things.

"While you try to mimic what's happening on Earth -- which is so complicated if you really think about it -- we have to use systems that we can control 100 percent," said Monsi Roman, chief microbiologist for the ECLSS project at MSFC. ECLSS depends on machines -- not microbes -- because, "if a machine breaks, you can fix it.

The water purification machines on the ISS will cleanse wastewater in a three-step process.

The first step is a filter that removes particles and debris. Then the water passes through the "multi-filtration beds," which contain substances that remove organic and inorganic impurities. And finally, the "catalytic oxidation reactor" removes volatile organic compounds and kills bacteria and viruses.

Once the water is purified, astronauts will do everything possible to use it efficiently. "On the ground, people flick on the faucet and they probably waste a couple of liters of water just because it's free and the water pressure is high," notes Carter.

"On the ISS, the water pressure will be about half what you might experience in a typical household," Carter said. "We don't use faucets on the ISS, we use a wash cloth. It's much more efficient. If you're an astronaut, you'll wet the wash cloth with a spray nozzle and then use the cloth to wash your hands." On the space station, people will wash their hands with less than one- One of the "nodes" that will become a tenth the water that people typically use on Earth. Instead of consuming part of the Space Station. The ECLSS 50 liters to take a shower, which is typical on Earth, denizens of the ISS life support equipment will be housed will use less than 4 liters to bathe. in Node 3, which is scheduled to be attached to the station in October 2005. Even with intense conservation and recycling efforts, the Space Station will gradually lose water because of inefficiencies in the life support system.

"We will always need resupply, because none of the water reprocessing technology that is available right now for space flight ... is 100 percent efficient. So there's always some minimal loss," said Marybeth Edeen, deputy assistant manager of environmental control and life support at NASA's Johnson Space Center.

Water is lost by the Space Station in several ways: the water recycling systems produce a small amount of unusable brine; the oxygen-generating system consumes water; air that's lost in the air locks takes humidity with it; and the CO2 removal systems leach some water out of the air, to name a few.

Lost water will be replaced by carrying it over from the Shuttle or from the Russian Progress rocket. The Shuttle produces water as its fuel cells combine hydrogen and oxygen to create electricity, and the Progress rocket can be outfitted to carry large containers of water.

NASA scientists will continue to look for ways to improve the life support systems of the Space Station, reducing water losses and finding ways to reuse other waste products. If the water recycling systems can be improved to an efficiency of greater than about 95 percent, then the water contained in the Station's food supply would be enough to replace the lost water, Edeen said.

"It takes processes that are slightly more efficient than we have developed for the space station to do that," Edeen said. "Those are the next generation water processing systems. Those are being developed now, but they're not ready for space flight yet."

The ECLSS life support system will join the Space Station as part of Node 3, which is scheduled to launch in October 2005. Until then, the environment inside the ISS will be maintained primarily by life support systems on the Russian Zvezda Service Module.