Why a Trip to Outer Space Could Be Bad for Your Bones

Have you ever seen space travel in the movies? For many people, space travel is a cool and exciting possibility. And it may not be too far off. NASA’s Orion spacecraft may send humans beyond Earth’s orbit. Humans have not gone beyond Earth’s orbit since 1972!

But don’t sign up for a trip to Mars yet! First, you might want to find out how travelling to space can affect your body. Even on short trips close to Earth, astronauts have suffered bone loss!

Did you know?

The term “space” is actually short for “outer space.” You already live in space!

On Earth, you experience the force of gravity. It is what keeps you from floating off into Earth’s atmosphere. Have you ever seen pictures or videos of astronauts floating around in their spacecrafts? This is called weightlessness. Astronauts float because the force of gravity is not very strong in space. This small amount of gravity is called microgravity. This is what damages astronauts’ bones. 

Why does this happen? To understand, let’s look at how bones are formed and maintained in your body.

What are bones made of?

Bones are a type of connective tissue that helps hold the parts of your body together. Bones are made up of bone tissue. Your bone tissue is very similar to your hair. One difference is that bone tissue also has minerals like calcium. Minerals give your bone tissue strength.

As you grow, your bones are constantly being broken down and rebuilt. This process is called remodelling. There are two main types of cells that are important for bone structure and maintenance. They have fancy names and do opposite things.

1. Osteoblasts (os-tee-oh-blasts) build bones using the same kinds of cells that build fat, muscle, and cartilage. 

   1. Osteoclasts (os-tee-oh-clasts) break up bones. They use the same cells as the immune system. These cells help osteoclasts dissolve the minerals on the outside the bone tissue. This releases calcium into the body in a process called resorption.

Osteoblasts and osteoclasts need to be in balance for your bones to stay healthy.

What happens to bones in space?

Problems with remodelling can lead to bone diseases like osteoporosis. Remember how your bones are always being broken and built? People with osteoporosis have more bone loss than bone building. This causes the bones to weaken, which can make break easily. 

Astronauts experience spaceflight osteopenia when they are in space. This condition can cause astronauts to lose bone mass in their legs, hips, and spines. Once the astronauts return to Earth, it can take three or four years for those bones to recover!

Scientists have learned that spending time in microgravity decreases bone building. This results in bone loss similar to osteoporosis. Remember, astronauts experience microgravity when they are in space. In microgravity, there is not as much stress on astronauts’ bones. That is mostly because they do not have to walk around. By having less stress on their bones, astronauts’ bones can become weaker. 

Scientists know that exercise is important for your bones. Exercise helps keep a healthy balance of bone building and bone loss. The best exercise for your bones on Earth is called load-bearing exercise. Walking, running, and playing sports like basketball are examples. Microgravity makes it hard to exercise in space. Astronauts must strap themselves down to treadmills in order to walk or run! 

Did you know?

Astronauts must exercise for at least 2 hours every day while they’re in space!

How are scientists studying bone loss in space?

Scientific are doing bone loss research on the International Space Station (ISS). Their goal is to learn more about bone loss in space and on Earth. For example, NASA has a program called Early Detection of Osteoporosis in Space. The scientists in this program  study what the best ways to prevent bone loss are. This project might help scientists find new ways to prevent bone disease. 

Space travel can be risky. But scientists are trying to reduce some of the risks - like the risk of bone loss! And who knows? They might even find a cure for osteoporosis along the way!