Effects of Space Radiation on Humans in Space Flight

Space radiation effects on human spaceflight include risks to crews from particulate radiation present in the space environment. Sources are all naturally occurring elements present in the galactic cosmic ray environment, charged particles emitted during solar eruptions, and particles trapped in the Earth's magnetic field. Historically, protection afforded by Earth's magnetic field results in low doses to crews in low Earth orbit. However, extended exposure to galactic cosmic rays and solar particle events during potential deep space missions could pose significant risks of developing a fatal cancer. Additionally, infrequent large solar energetic particle events could give radiation doses large enough to manifest acute radiation syndromes in crew members, thereby resulting in radiation sickness and possibly death. This chapter looks at analyses of solar energetic particle events, often referred to as space weather. Most solar events pose little or no health hazards to space crews. But a few during each solar cycle could expose lightly shielded crews to doses sufficient to pose some health risks. Rare extremely large solar energetic events could expose crews to radiation levels that may be mission threatening or life threatening. This chapter presents potential biological effects of solar and galactic cosmic radiation on humans in deep space.