NASA closely monitors astronaut health during missions and throughout their lifetime. These medical monitoring programs, as well as prospective studies and medical research, help understand potential health risks related to long duration spaceflight, including the agency's Journey to Mars.

Biomedical research that aims to prevent heart disease is an important part of the NASA Human Research Program. One example is the Cardio Ox study, which uses the unique microgravity environment of the International Space Station to understand changes to the cardiovascular system in astronauts living and working in low-Earth orbit.

Radiation is another top health concern for astronauts. Crew members who travel beyond low-Earth orbit will be exposed to more and different types of radiation because they will not be protected by Earth's magnetosphere. The National Space Biomedical Research Institute, a non-governmental organization with funding from NASA's Human Research Program, supported a recent study published in Scientific Reports that looked at the rate of cardiovascular disease among Apollo astronauts.

With the current limited astronaut data referenced in the study it is not possible to determine whether cosmic ray radiation affected the Apollo astronauts. The study group comprised seven of the 24 men who flew in the Apollo program; five women and 30 men who have flown in low-Earth orbit; and 33 astronauts-three women and 32 men-who have not flown on missions.

In addition to the small study size, limitations of the research include lifestyle factors that cannot be quantified, such as family genetics and diet, which are known risk factors for cardiovascular disease.

The agency recognizes the importance of this research area and supports a comprehensive program to assess the potential health effects for crew members from space radiation exposure. NASA uses ground research facilities to study how radiation affects biological systems, and more importantly, how to protect them. Scientists also are developing unique ways to monitor and measure how radiation affects people while living in space, and to identify biological countermeasures. Finally, NASA is exploring methods to optimize radiation shielding for spacecraft and habitats.

NASA research on both acute and long-term health risks from space radiation include studies about possible increased incidence of cancer and acute radiation sickness, degenerative tissue damage, diseases such as heart disease and cataracts, and early and late central nervous system damage.

NASA's Human Research Program enables space exploration by reducing the risks to human health and performance through a focused program of basic, applied, and operational research. This leads to the development and delivery of: human health, performance, and habitability standards; countermeasures and risk mitigation solutions; and advanced habitability and medical support technologies.