Space travel - not such an easy journey
Space travel is no walk in the park. If you think being an astronaut is fun and glamorous, you might want to read up on all the side effects.
Living and working in zero gravity plays havoc on all parts of your body, including your musclar, skeletal and vestibular (balance) systems. On top of that, NASA has identified 442 medical conditions that could require emergency attention during long-term missions. Now do you still want to be an astronaut?
A stomach-churning experience
One of the most common - and unpleasant - effects of microgravity is space motion sickness, caused when the brain and inner ear receive mixed signals. Between 40 to 50% of astronauts experience this.
On Earth, we can tell which way is up and which way is down because gravity tells us so. Sensors in the inner ear feel this gravitational pull and send information to the brain about our body's orientation.
In space there is no gravitational force telling the inner ear which way is 'up' and 'down'. So while our eyes can certainly see a ceiling and floor in the spacecraft, our brains cannot register this. This causes nausea and dizziness. Some astronauts experience headaches and vertigo.
Fortunately, symptoms subside within the first few days of travel and common motion sickness medicine is just as effective in space.
Puffy face and bird legs
Two thirds of our bodies are made up of fluids. On Earth, gravity pulls most of this towards our legs. In zero gravity, fluids naturally travel upwards into our face and head, causing them to look swollen. This gives astronauts 'puffy face syndrome'. The extra fluid in the head may lead to blocked noses and sinuses but once astronauts are back on Earth, they return to their normal appearance.
This fluid shift can result in the loss of about a litre of fluid in each leg, creating what some call 'Bird Legs'.
Under the ray gun
The Earth's magnetic field protects us from harmful radiation. We are still exposed to small amounts when we go for medical x-rays, when we travel on transcontinental flights or just from radons in the air. However, astronauts are exposed to 10 times as much radiation - and that's just in low Earth orbit.
In deep space, astronauts can be exposed to even higher doses. During solar storms, a single dose of radiation could be equivalent to several hundred chest x-rays. Therefore it's essential that all spacecrafts have designated storm shelters because large amounts of radiation can cause severe damage by altering DNA in the genes.
Exercise, exercise, exercise
In zero gravity, muscles do not have to do as much to move around. If astronauts don't work hard to counter this, they will face severe muscle loss. It's exactly the same as lying in bed for months on end - if you tried to get up and move around afterwards, you'd find that your legs were very weak.
The same applies to bones. Bones demineralise, losing calcium and strength in space. In effect, osteoporosis sets in. Astronauts risk losing 2% of their bone mass for every month spent in zero gravity.
Learn more about osteoporosis from BBC Health
To reduce muscle and bone loss, astronauts have to exercise for two or more hours every day. It's not just a matter of running on a treadmill or doing some sit ups - odd looking contraptions have been designed to make exercising in zero gravity effective.
The problems don't end once astronauts return home. In fact, most astronauts have more trouble re-adapting to Earth's gravity than adapting to microgravity in orbit. Their muscles and bones have weakened, making it difficult to walk. The heart has to recondition itself to pump blood harder to overcome gravity.
In April 2004, astronauts on the Russian Soyuz mission had to be helped out of the spacecraft by Russian space rescue service staff and carried away into waiting helicopters after landing. Astronauts Michael Foale and Alexander Kalery had been in orbit for six months.
Space travel is certainly an adventure, but not an easy one.
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