Traveling to Mars is simple in sci-fi movies, but in reality it causes short-term and long-term health problems.

Space sickness

Almost 40 percent of astronauts experience a form of motion sickness in space. Along with nausea and vomiting, symptoms include headaches and dizziness.

Blood circulation

In microgravity, the cardiovascular system doesn't work as well as on Earth, triggering fluid shifts. As fluids move up from the lower body to the trunk, the heart rate increases and blood pressure rises. Astronauts experience puffy faces, headaches, nasal congestion and develop skinny legs.

Compromised immune system

Studies conducted in space show isolation and sleep deprivation may cause compromised immunity. Astronauts are more prone to infection by common and latent viruses.

Backaches

Caused by the relaxation of the back muscles and ligaments, astronauts become taller. Once they return to Earth, they shrink back to their former height.

Muscle loss

Without gravity, there's no need for astronauts to walk, stand or lift anything. Their muscles, particularly in their legs, atrophy.

Fatigue

Constant noise and irregular light patterns make it difficult to sleep on board a spacecraft. Astronauts may experience fewer hours of regular sleep and have poor quality sleep.

Psychological effects

Long-term isolation, monotony, limited mobility and living in close quarters with other astronauts can lead to depression, interpersonal conflicts, anxiety, insomnia and even psychosis.

Bone density loss

Weightlessness causes the human body to excrete calcium and phosphorus (in urine and feces), resulting in rapid bone density loss.

Radiation

Long-term exposure to ionizing radiation in open space is a significant concern for the crew of a Mars mission.