A day in space
Astronauts have very busy lives. Each day in orbit (apart from rest days) is carefully planned by mission control. The times used by the crew are based on those at the mission control centres in Houston, Texas, or Moscow.
The 12-hour working day on the International Space Station begins with a wake-up call. After a quick rub down with a soapy cloth, the crew have breakfast and run through the jobs for the day with mission control.
Space stations are like large, complicated houses that need constant care and attention. A lot of time has to be spent on housekeeping chores – such as cleaning and repairs.
Astronauts Gorie and Mohri
Eating in space
There are three meal sessions – breakfast, lunch and dinner – though drinks and snacks are always available. Much of the crew's time is spent preparing and carrying out scientific experiments. This may involve speaking to scientists on the ground.
At least two hours each day are spent on exercise. This is essential to keep the crew fit and healthy. Loading ferry craft with rubbish and unloading fresh supplies is a major task. Many hours can also be spent getting ready for spacewalks.
Learning to live together
Do you feel homesick after being away for a week or two? Do you feel lonely after being on your own for a few hours? If so, you may not enjoy being an astronaut.
In some ways, living in a space station is like being stranded on a desert island. A crew of two or three astronauts has to survive far from home for weeks or months at a time.
If their mission is to be a success, they have to learn to live and work together as a team. This is not easy when they may have known each other for only a year or two.
ESA astronauts come from many different countries. They have to fly with astronauts from the United States, Russia and Japan. All of these space travellers have different languages, different customs and different ways of looking at things.
Crew members have to learn to share jobs such as cleaning and repairs. They also have to talk over problems and agree how to overcome them.
Fortunately, astronauts can now send e-mails and talk to their families over video links. The isolation is also broken by regular deliveries of mail and visiting crews.
Washing up
Living in a space station is rather like living in a desert. There is very little water available and every drop is precious.
The Space Shuttle has fuel cells that combine hydrogen and oxygen to make electricity. Large amounts of water are made as a by-product. But there are no fuel cells on the International Space Station (ISS).
Nearly all of the water used on the ISS has to be brought from Earth by the Shuttle or automated craft such as Russia's Progress or ESA's ATV. Astronauts use this for drinks and preparing food.
Some previous space stations were equipped with showers, but these are not fitted in the Shuttle or the ISS. Instead, astronauts use a damp, soapy cloth for washing. There is no washing of dirty dishes either. Used food containers are crushed and thrown away.
Some water on the ISS is taken from the air and recycled. A Russian unit can produce 24 kg of water per day in this way. This is purified and used for drinking or food preparation.
The toilet uses a flow of air instead of water to flush away the human waste. Urine produced when astronauts use the toilet is also purified and recycled.
Meals for Martians
Look around any supermarket and you will see thousands of different types of food. A typical café or restaurant may have a dozen or more items on the menu. But what will be eaten by the first astronauts who land on Mars?
In an effort to answer this question, ESA asked French chefs at the companies GEM and Alain Ducasse Formation (ADF) to create Martian meals. Their task was to make tasty dishes using only a few ingredients that could be grown in greenhouses far from Earth.
Spirulina gnocchis
They came up with 11 incredible recipes, including ‘Martian bread and green tomato jam’, ‘Spiruline gnocchis’ and ‘Potatoes and tomatoes mille feuilles’.
"Following intensive work, we finally have created healthy, tasty and fresh dishes, which is the realisation of a great challenge,” said Armand Arnal, the chef who created the recipes.
Potato and tomato mille-feuilles
Armand’s nine basic ingredients were: rice, onion, tomato, soya, potato, lettuce, spinach, wheat and spirulina. All of these are well known except spirulina, a type of blue-green seaweed that contains many proteins, calcium, carbohydrates and vitamins – ideal eating for astronauts working in extreme environments.
Martian bread and green tomato jam
The nine food crops had to account for at least 40% (two-fifths) of the final recipe. The rest could be made up of extra vegetables, herbs, oil, butter, salt and other seasoning brought from Earth.
“Why 40%? The plants will then be able to produce enough air and water for people to live,” said Christophe Lasseur of ESA. “We get ‘for free’ the needed oxygen and water.”
Gravity and weightlessness
Our everyday lives involve such activities as sitting, walking, picking up things from the ground and lying in bed. None of these activities are possible in orbit.
Once a spacecraft reaches orbit, everything inside it appears to be weightless. Anything (or anyone) that is not tied down will float.
Astronauts first feel the effect of weightlessness when the rocket engines are turned off. Straight away, they begin to float, held down only by seatbelts. Weightlessness allows astronauts to appear superstrong. They can lift objects that would be far too heavy to move on Earth. But there are some drawbacks.
Without the effect of gravity, blood and other body fluids begin to flow towards the head. This can cause a feeling of stuffiness and headaches. With no gravity to push against, bones and muscles can become weak. To stay fit, they have to exercise several hours each day. This allows them to recover more quickly when they return to Earth.
In a shuttle or space station, there is no up or down. There is no difference between a floor and a ceiling. This can make astronauts feel sick until they get used to this strange arrangement.
Weightless experiments help industries on Earth
A typical stay on board the International Space Station (ISS) lasts about six months. But how do the crew members occupy their time while they are up there? Quite a lot of their daily activity is taken up with carrying out experiments that could have practical applications back on Earth.
The ISS is the largest and most advanced workshop ever flown in space. By using its specially equipped modules, such as ESA’s Columbus lab, scientists can study a wide range of subjects in a very special environment, where everything is weightless. On Earth, gravity strongly influences everything we do, but some very odd things happen when the effects of gravity disappear.
A flame in microgravity
We are used to seeing a candle flame with a tapered shape. The pointed flame is formed when the hot gases rise, because they are lighter than the cool air that surrounds them. This cool air is drawn into the base of the candle wick, and provides oxygen to keep the candle wax burning. But in weightlessness, the hot gas is no lighter than the cool air, so it does not rise. The result is a small, almost invisible, round flame. The actual burning takes place only on the surface of the flame, where fuel from the candle wax can mix with the oxygen in the air outside.
Scientists can learn a lot by studying the way things burn in weightlessness. This knowledge can then be used, for example, to design car or aircraft engines that use less fuel and create less pollution.
Another interesting research area involves mixing liquids. Many of the metals in everyday use are alloys - mixtures of two or more metals. Alloys are made by melting the metals so that they mix together. On Earth, gravity strongly affects the way the different liquid metals combine, but the mixing is much easier in space. Experiments under weightless conditions are teaching us a lot about this process, so that better alloys can be made back on Earth.
Spacewalks
Imagine walking in space and flying around the Earth at more than 27,000 km/h! This is what hundreds of spacewalkers have experienced in the last 50 years. Spacewalks (officially known as Extravehicular Activity or EVA) are an essential part of working in space. They are used to install new equipment and experiments, and to carry out repairs. Almost 1,000 hours of spacewalks have been needed to build and maintain the International Space Station since 1998.
Spacewalkers wear protective suits when they enter the airless vacuum of space. These suits have many different layers which keep the wearers at the right temperature, enable them to breathe, and protect them from harmful radiation. The oxygen pressure inside the suits is lower than in the Space Station. As a result, astronauts have to spend about four hours breathing oxygen inside an airlock before they can step outside.
There are two different pressure suits stored on the ISS. The American suit has two sections: a hard upper torso and a flexible lower torso. These sections connect at the waist. The astronaut’s legs are pushed into the trousers, then the arms and upper body are placed in the upper section. The Russian suit has a hard upper section with a back door which also houses the life support system. This makes it easier to put on single-handed. Both suits have separate gloves and helmets.
Spacewalkers are often carried from place to place on the end of a robotic arm. There are also special hand rails to help them move around. To stop them floating away and being lost in space, they are connected to the Station by thin cords. Spacewalks can last for many hours. The record is held by Susan Helms and James Voss, who spent nearly 9 hours in space in March 2001.
Weak muscles
We rely on our muscles to walk, lift objects and climb stairs. However, in space muscles become weaker when there is no gravity to overcome. When astronauts come back to normal gravity on Earth, they suddenly feel very heavy and find it hard to keep their balance. Similar effects occur in elderly people and those who spend a long time in bed through illness.
Space studies give an opportunity to learn more about the effects of long-term muscle wasting.
Keeping fit
Treadmills are used in space to prevent muscle weakness
Tests with astronauts have shown that several hours of daily exercise are needed to prevent muscle weakness. Among the machines used in space are treadmills for running on the spot and exercise bicycles. These are important for strengthening muscles and improving blood circulation.
Astronauts may also wear special trousers that pull blood to their legs and make the heart pump harder. These and other measures, such as drug treatment, have possible uses for patients on Earth.
One new machine being developed by ESA is the Flywheel Exercise Device. This includes a spinning wheel and can be used for exercise both in space and on Earth. It was launched to the International Space Station with ESA’s Columbus lab in February 2008 and is used as an advanced exercise device for astronauts. It will eventually be available for recovering patients and for training athletes.
Bed restMajor changes occur
in the human body during long space missions. These include gradual
loss of muscle and bone, space sickness, and changes related to the
heart and lungs.
Such changes can affect astronauts' well-being and efficiency, both in orbit and after their return to Earth. Many
studies have been undertaken in order to learn more about the creeping
effects of weightlessness. One of the easiest and cheapest ways of doing
this is bed rest studies. Numerous
bed rest studies have been performed during the last 40 years. These
have provided important information about how people cope with long
periods of inactivity.  -6° head down tilt Volunteers
stay in bed for many weeks, often lying with their head tilted down.
With little use of bones or muscles, their bodies behave in similar ways
to how they would in space.
Scientists use these studies to test new drugs and other ways of
counteracting the effects of weightlessness. Many spin-off instruments
and treatments have spread to clinics and helped patients.
Future research on the International Space Station promises even more
health benefits. Eventually, this research will also pave the way for
humans to travel beyond Earth orbit and explore other worlds.
Bone loss
50% of women over 60 years of age suffer from brittle bones. As seen through a microscope, the centre of the bone seems to be eaten away. This leads to a marked increase in fractures of the hip, wrist or spine. The problem is largely caused by illness and lack of exercise.
A similar problem also occurs in the weightlessness of space, when even the youngest, fittest astronauts suffer some bone loss.
Space research is helping scientists to understand what happens and to find a way to combat the problem.
One method is to use volunteers who stay in bed for many weeks. These bed rest studies show how bones change when no weight is being put on them.
ESA is also developing new exercise machines and medical equipment for use on Earth and in space.
One device tested on ESA microgravity flights is a step-on, step-off machine. Another mimics normal walking and running by testing the effects of vibrations on bone.
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