Life on board the Space Station

The weightlessness in space does not mean everything is easy to handle. Tools and equipment still have inertial mass and as the astronauts are weightless it can be hard work pushing and pulling to move objects around.

For one thing it is difficult to brace your feet and this leads to astronauts taking up awkward positions in an effort to stay upright. To make activities easier on board the ISS, there are numerous restraining loops which astronauts use to anchor their feet.

Keeping in shape!

Before the first human spaceflight scientists were not sure that humans could even survive in a state of weightlessness, this is one of the reasons why Yuri Gagarin only made one orbit. The biggest physiological problems facing astronauts are the loss of bone and muscle mass.

"Nowadays much more is known about muscle loss," says Dag Linnarsson who is a professor at the Karolinska Institute just outside Stockholm. His main field of enquiry is the effect of extreme environments on humans, with a particular focus on weightlessness.

"Bone mass is a little bit more difficult," says Linarsson. "The only way to measure the loss of bone accurately is by x-ray but you cannot X-ray astronauts all the time. Work is being done to find other methods but there is still a way to go."

Fortunately, however, once back on Earth astronauts regain most of the tissue lost in about the same time it took to lose it.

Swedish training regime

Swedish researcher Per Tesch has made a significant contribution to avoiding the loss of muscle tissue. Thanks to new training methods, astronauts today get more results from just a few minutes of training than they did from hours of exercise. Per Tesch has also developed a new training tool that promises to aid space travellers even more.

Other physiological problems resulting from spaceflight are a decrease in the number of red blood cells and a slight degradation of the immune system.

Many problems that astronauts have to contend with are similar to those which afflict the elderly. This means that research into improving the physiological condition of astronauts holds the promise of being useful for life on Earth as well.

Important to sleep in a draught

Everyday actions that we take for granted on Earth pose some of the greatest challenges to astronauts. Sleep is one of them. Many astronauts hook their sleeping bags to the walls to avoid floating around in the air currents caused by the ventilator fans and bumping into things.

These fans are essential. It is very important to sleep in the currents of air they create, even if it can get a bit breezy. In weightlessness the warm air exhaled can not go 'up' so it settles in a bubble around the astronaut. Without the ventilation this would eventually lead to oxygen starvation, carbon dioxide poisoning and at best a splitting headache.

"Most astronauts sleep less in space", says Frank De Winne, the Belgian astronaut who visited the ISS in 2002. "It is more difficult to fall asleep and to go back to sleep if you are awakened."

Confusing

About 50% of astronauts suffer from space sickness, a form of motion sickness similar in both causes and symptoms to seasickness.

The human sense of balance detects the orientation and motion of the body with great accuracy and relays this information to the brain. Thanks to this information the brain can compensate for sudden changes and keep the body upright. But this finely tuned system does not work in space; instead the brain receives a chaotic mix of conflicting signals and astronauts become disorientated.

It takes a few days for the brain to come to terms with these new conditions and to use visual input to orient the body: down is wherever the feet happen to be.

When the astronauts return to Earth they usually suffer from problems with balance for a while. Other habits learnt in space can cause problems of a different kind. Russian cosmonauts who made very long duration flights have been known to let go of cups and other items in mid air after their return to Earth.

Personal hygiene

The toilet is not the most appreciated piece of equipment on the ISS. It uses no water but has a powerful fan that sucks the faeces through an opening at the bottom. In order for this to work, the astronaut has to be tightly seated and held in place by powerful straps. As Frank De Winne points out, "the toilet also takes a while to prepare, so a good hint is to leave it clean and fresh for the next astronaut!"

There are 'space showers' on board but they do not work very well. The ISS crew use wet towels and space shampoo and a hot bath or shower is usually high on an astronaut’s wish list on return to Earth.

"Other things you miss are cold drinks, good food, friends, and private time and space" says Frank De Winne, "and then there is the shower ..."

But, the satisfaction of working as part of an extremely dedicated team with tremendously challenging tasks is a huge compensation, as is "the view out the window of our amazingly beautiful planet, there is no view that even comes close," adds Frank De Winne.