What is happening to Mark Shuttleworth's body in zero gravity today?
With the space shuttle in zero gravity orbiting the earth, the cosmonauts can float around the interior of the cabin. They are able to walk up walls and ceilings and pick up heavy objects on their fingertips.
For the first two days, the body is confused by the lack of gravity. By the third day, the brain and balance organs in the ears are adapting and Mark should feel the nausea and dizziness subside.
Body fluids: still puffy
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 fluid shift would have caused Mark to have a puffy face and a blocked nose. But his kidneys will have started to adjust and will have released a lot of fluid through urination.
The loss of fluids causes the cosmonauts to feel less thirsty and so drink less, and also reduces the amount of blood plasma and cells in the body.
The initial increase in blood flow to the chest area caused the heart to enlarge and to beat slower. After the third day, the heart again begins to change size.
Once blood volume has started decreasing – within two to three days – the heart starts to shrink. It can be reduced to a third of its original size. Mark's heart rate will begin to increase again and will stabilise at roughly the same rate as prior to launch.
In weightlessness, Mark will not have to use his muscles as much to get around, and so his heart does not have to work as hard as on earth. Cosmonauts exercise as much as possible to prevent the reconditioning of the heart muscle.
Cosmonauts will not feel adverse affects from these changes as the body adapts to a 'sapce-normal' condition.
A cosmonaut'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.
Their saliva contains more bacteria and viruses than it would on earth.
The weakening of the skeleton, that began on the first day, continues. Losing bone mass is one of the most serious effects of space travel.
A cosmonauts can lose up to one percent of bone mass per month in space.
Mark will exercise for two and a half hours per day to prevent bone and muscle loss. He will be strapped to his training apparatus to prevent him from flying all over the shuttle.
Cosmonauts can lose 10-20 percent of the muscle mass on a shirt mission. The muscles most affected by space travel are the leg and spine muscles.
- (Health24, April 2002)