You are 63 years old. Past and future: You were 62 years old in 2020.

Bone loss occurs in the weightless environment of space because bones no longer have to support the body against gravity. On Earth, gravity applies a constant mechanical load to the skeletal system, that causes healthy bones to maintain a certain density so that they are able to support the body.

They found classic symptoms of what is now known as Space-Associated Neuro-Ocular Syndrome (SANS). Symptoms include swelling in the optic disc, which is where the optic nerve enters the retina, and flattening of the eye shape.

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.

Our study is still ongoing; however, early results suggest that astronauts can reduce the risk of bone loss and renal stones by proper intake of appropriate nutrients, such as calcium and vitamin D, an effective exercise program and minimal amounts of medication. Bone loss is also observed in bedridden older people.

This condition can cause astronauts to lose, on average, one to two percent of their bone mass every month. This bone loss typically happens in the legs, hips, and spines of astronauts. Once astronauts return to Earth, it can take three or four years for those bones to recover!

Bone remodels in response to stress in order to maintain constant strain energy per bone mass throughout. On Mars, where gravity is about one-third that of earth, the gravitational forces acting on astronauts’ bodies would be much lower, causing bones to decrease in mass and density.

Since the 1990s, resistance exercise has been thought to be a key method of protecting astronauts’ bones. Normal, healthy bone constantly breaks down and renews itself, a process called remodeling. As long as these processes are in balance, bone mass and density stay the same.

This leads to a lowered bone density, the same effect that microgravity has on astronauts. As a result, bones become more fragile and are more susceptible to fractures, especially in the hip, spine, and wrist.

An astronaut can choose from many types of foods such as fruits, nuts, peanut butter, chicken, beef, seafood, candy, brownies, etc. Available drinks include coffee, tea, orange juice, fruit punches and lemonade. As on Earth, space food comes in disposable packages.

A major challenge astronauts face during prolonged space missions is the simultaneous loss of bone and muscle, which weaken and atrophy due to disuse outside the constant pull of Earth’s gravity. Previous research found that in microgravity, astronauts can lose up to 20% of their muscle mass in less than two weeks.