While the earth's atmosphere and magnetic field protect us from most of the radiation, astronauts will be exposed to large doses of dangerous electromagnetic waves that pose significant risks of genetic damage and increase lifetime risk for cancer, central nervous system effects, and degenerative diseases.

It's fun when we see astronauts floating in the space station, but actually long-term exposure to microgravity is harmful to us. Astronauts may suffer from loss of bone and muscle density, damaging their capability to perform critical tasks and posing threats to their health.

Hypergravity environments will be observed at the launching and landing part of the space travel. However, an average human body as we know it can only withstand up to 5g of gravity before it gives in and pass out. Blood will be drawn to our legs and our brain will not be able to function.

Circadian rhythm disorders are caused by desynchronization between internal sleep-wake rhythms and the light-darkness cycle. Millions of years of evolution on planet earth gave us the internal clock that coordinates with its rotation almost perfectly. However, when traveling in space, this internal clock lost its purpose and may instead disturb our capability to perform critical tasks.

We can barely imagine the hidden threats during our space travel, which may require us to stay alert and execute operations over a long period of time. However, recent studies shows that on-orbit space travel caused less sleep time and lower sleep quality. How can we guarantee better sleep, while stay awake for a long period of time if needed?

Traveling far from home, food and water supply will be big issues as restocking supply from our mother planet earth is basically impossible. In addition to developing systems to produce food and recycling water, long-term space traveler will also need to figure out ways to save on every bit of resource possible.

It is inevitable that medical conditions of varying complexity, severity, and emergency will occur during spaceflight missions with human participants. With limited resources and expertise, how can we achieve the best chance of survival in case of a medical emergency?