Space travel - not such an easy journey
Living and working in zero gravity affects all parts of your body, including muscular, skeletal and vestibular systems.
A stomach-churning experience
One of the most common 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. Fortunately, symptoms subside within the first few days of travel and common motion sickness medicine is just as effective in space.
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.
To reduce muscle and bone loss, astronauts have to exercise for two or more hours every day. Odd looking contraptions have been designed to make exercising in zero gravity effective.
Under the ray gun
The Earth’s magnetic field protects us from harmful radiation. We are still exposed to small amounts, for example when we go for medical x-rays. 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.
Image: Aki Hoshide on a spacewalk. NASA.