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A Voyage to Mars: Bone Loss in Space: Why do bones get weaker with less gravity and how can we prevent bone loss in space?
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- A voyage to Mars: bone loss in space
- The ultimate goal for human space flight
- is sending a human to Mars.
- It's not an easy task though.
- The journey to Mars takes about six months,
- Then, astronouts would spend about two years on the surface,
- before making their six month journey back to Earth.
- A trip like this has serious consequences to the human body.
- Especially your bones.
- Your bones? But why?
- Living in less gravity causes your bones to break down
- and become weaker.
- That doesn't make sense. Astronauts travel in space all the time.
- Right?
- Yes, but they lose one to two percent of their bone per month.
- Why do bones get weaker with less gravity?
- And how can we prevent bone loss in space?
- On earth, we are adapted to one G of gravity pulling us toward the center of the planet.
- On a mission to Mars, a total of one year of the trip would be spent in weightlessness.
- Astronauts could lose between twelve to twenty-four percent of their bone.
- Then, once the astronaut reaches Mars, they would be living in forty percent of the Earth's gravity.
- We don't even KNOW how much additional bone they will lose.
- Every time you take a step, jump, or flex a muscle,
- you put stress on your bones.
- That stress damages them, and causes tiny microfractures.
- Don't worry, this is a good thing. In fact, your body was built to handle the impact,
- and fix the microfractures.
- To fix the problem, your body sends in a cell called an osteoclast, to go in and eat away the damaged bone.
- When the osteoclast is done, new cells called osteoblast rebuild the bone back up.
- This process is called remodeling, and in the end,
- your bone is healthier than they were before.
- In space, without gravity to cause the microfracture, the process of remodeling is altered.
- Osteoblast do less building, and osteoclast seem to eat away more bone.
- As a result, your skeleton isn't as healthy as when you left earth.
- Not all bone loss is equal though.
- The most change happens in the weight-bearing part of your body,
- like the lower spine, hips, legs, and feet.
- No one knows exactly why.
- Maybe your body thinks your bones are overbuilt, or maybe gravity affects osteoblast and osteoclast.
- But either way,
- the shape of your bone changes, and not for the better.
- If you look at the crosssection of your bone, this constant eating and rebuilding
- causes the shape to change.
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