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During lift-off
Space travel isn't for the faint-hearted. Cosmonauts experience a force of between three to five times the force of gravity during lift-off. The space shuttle accelerates within minutes to more then 27 000 km/h.

Binnie was strapped into his seat in a supine position during lift-off, so that the incredible acceleration, which lasted almost 20 minutes, could not cause him any harm. He would have felt heavier and may have struggled to lift his arms.

A supine position during lift-off is important. If he had been seated in an upright position, he would have blacked out due to blood pooling in the lower half of his body.

At zero gravity
Once SpaceShipOne left the earth's atmosphere and began to orbit the earth, our hero began to float. Generally, cosmonauts are able to walk up walls and ceilings and can pick up heavy objects with their fingertips.

Organs drifting in space
In zero gravity, the organs of the body are weightless. As the chest expands due to less pressure on it, the organs shift and float in the abdominal cavity.

Cosmonauts who spend some time in space, experience the following:

Fluid loss
Due to the lack of gravity, the body's fluids do not concentrate in the lower half of the body, but shift to the head and chest area. This is why cosmonauts' faces puff up while their legs shrink.

The fluid shift also causes the body to eliminate what it thinks is an overabundance of fluid by increasing its urine output. That's why cosmonauts who spend a number of days in space (such as Shuttleworth in 2002), wear a type of nappy during lift-off to store the urine until it can be removed to the shuttle's waste system later on.

The blood
Because the overall fluid level in the body decreases, blood volume also decreases. The body starts reducing its output of red and white blood cells to compensate.

Although this change will not really affect the cosmonauts in space, they will feel the effects when they return to earth.

The heart
The shift of blood and fluid to the chest causes the heart to pump harder. The heart starts to enlarge to handle this extra blood.

Cosmonauts have to adhere to strict physical fitness training programmes. This is maintained in space. They spend at least two hours a day exercising to prevent loss of heart function.

Space sickness
In space, there is no up or down. The body becomes confused and cannot tell its orientation or even where the arms and legs are. These changes cause a feeling similar to that of seasickness. Cosmonauts often suffer from nausea, headaches and loss of appetite, and struggle to maintain an efficient work rate aboard the space vehicle.

Bones and skeleton
Weakening of the skeleton is one of the most serious effects of space travel. The bones lose so much density – similar to that of accelerated osteoporosis – that the risk of fracture is five times greater.

Travellers who are in space for an extended period of time, can lose up to one percent of bone mass a month. A trip between three and six months can cause bone loss that can take between three to six years to replace. Some researchers believe that the bone density can never fully be recovered.

Exercise is the best way to prevent bone loss, but this can be difficult in space. Cosmonauts have to be strapped to equipment, otherwise they might go bouncing off against the walls of the shuttle.

Fertility
One of the surprising effects of zero gravity, is that cosmonauts' sperm swim faster than on earth.

Immune system
A space traveller's immune system is affected by space. Fewer of the body's T-cells (which fight infection) are produced, and those that are, are less effective than here on earth.

It is hardly surprising that the saliva of cosmonauts contains more bacteria and viruses than on earth!

This reduction in T-cells, coupled with the fact that cosmonauts often do not get enough sleep in space, weaken the immune system, making it more likely that the crew members will get sick.

Cosmonauts have to be extremely conscious of hygiene and cleanliness. The water is heated and treated with iodine to kill bacteria. The air is filtered through ventilators and humidity is kept as low as possible. Food is irradiated to kill any germs that may be present.

Emotional influences
Tension, anxiety and being cooped up in a 19 square metre space shuttle can impact negatively on emotional wellbeing.

Muscles
Cosmonauts can lose 10 to 20 percent of their muscle mass during a space trip. Muscle fibres can even change their type to adapt to motion in space.

The greatest loss of muscle occurs in the spine and leg muscles. Exercise is essential to prevent muscles from atrophying (shrinking).

Internal clock
Cosmonauts sleep roughly six hours per day. The spacecraft orbits the earth every 90 minutes, so the crew is exposed to 45 minutes of light followed by 45 minutes of darkness. This causes sleep disruptions, which is why almost half the medication used on board the space shuttle is used to help cosmonauts sleep.

In spite of all of this, who wouldn't want to board a space craft?! Health24 takes its hat off to the likes of Mark Shuttleworth, Michael Melvill and Brian Binnie!

 

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