The NASA Engineers, use the lessons learned to better design spacecraft and improve the fit and functions of spacesuits. The research also aids in the development and assessment of medical standards, physical fitness programs and standards, physiological and psychological adaptation training, sensorimotor training, and nutritional health protocols.

NASA is particularly interested in investigating how the body reacts to long-duration spaceflight as the agency plans for extended missions on the Moon and Mars. 

SPACE RADIATION

On Earth, we are shielded by the planet’s magnetic field and atmosphere from the majority of particles that make up the space radiation environment. Even so, everyone on Earth is exposed to low levels of radiation every day, from the food we eat to the air we breathe. 

In space, astronauts are exposed to varied and increased levels of radiation that are different from those on Earth. Three major sources contribute to the space radiation environment: particles trapped in Earth’s magnetic field, solar energetic particles from the Sun, and galactic cosmic rays.

A big challenge in reducing the risks of radiation exposure is that some space radiation particles especially galactic cosmic rays are difficult to shield against. Exposure to increased radiation can be associated with both short- and long-term health consequences, depending on how much total radiation astronauts experience and the time frame in which they experience that exposure.

Increased risk of cancer and degenerative diseases, such as heart disease and cataracts, have been observed in human populations exposed to radiation on Earth. Health risks for astronauts from radiation exposure in space are mainly driven by long-term impacts.

Additionally, animal and cellular research indicate that the type of radiation in the space environment has a larger impact on health outcomes compared to the radiation experienced on Earth. Not only will astronauts be exposed to more radiation in space than on Earth, but the radiation they are exposed to could pose increased risks.

The current strategy to reduce the health risks of space radiation exposure is to implement shielding, radiation monitoring, and specific operational procedures. Compared to typical six-month space station missions, later Moon and Mars missions will be much longer on average. Consequently, the total amount of radiation experienced and associated health risks may increase.

NASA is developing new radiation detectors.

Ensuring astronauts get quality sleep is also important; otherwise, their internal biological clocks, or circadian rhythm, might be altered by factors like different dark and light cycles, a small and noisy environment, the stress of prolonged isolation and confinement. 

NASA scientists are using devices, such as actigraphy, that help assess and improve sleep and alertness by recording how much people move and how much ambient light is around them. New lighting, spurred by the development of Light-Emitting Diode (LED) technology, is used on the space station to help align astronaut’s circadian rhythms and to improve sleep, alertness, and performance.

GRAVITY FIELD

Transitioning from one gravity field to another is trickier than it sounds. It affects spatial orientation, head-eye and hand-eye coordination, balance, and locomotion, with some crew members experiencing space motion sickness.

When shifting from weightlessness to gravity, astronauts may experience post-flight orthostatic intolerance where they are unable to maintain their blood pressure when standing up, which can lead to lightheadedness and fainting.

NASA has learned that without Earth’s gravity affecting the human body, weight-bearing bones lose on average 1% to 1.5% of mineral density per month during spaceflight. Without the proper diet and exercise routine, astronauts also lose muscle mass in microgravity faster than they would on Earth.

Moreover, the fluids in the body shift upward to the head in microgravity, which may put pressure on the eyes and cause vision problems. If preventive or countermeasures are not implemented, crews may experience an increased risk of developing kidney stones due to dehydration and increased excretion of calcium from their bones.

CLOSED ENVIRONMENT

NASA has learned that the ecosystem inside the spacecraft plays a big role in everyday astronaut life in space. Microbes can change characteristics in space, and micro-organisms that naturally live on the human body are transferred more easily from person to person in closed habitats, such as the space station.

Stress hormone levels are elevated and the immune system is altered, which could lead to increased susceptibility to allergies or other illnesses.

Venous Thromboembolism is a situation in which, Stagnant or reverse flow in the internal jugular vein has been observed in  crew members . This is an emerging finding and has potential impacts on flight participants with cardiovascular conditions.

Exposure to the isolation and confinement of spaceflight can result in decrements in cognitive and behavioral functioning.

Astronauts find they grow a little taller during their stay on the ISS as their spines elongate slightly. This can lead to issues such as back pain while in space and slipped discs once back on Earth.  Dr Vinay Gupta, a pulmonologist from Seattle, observed that William’s cheeks, apparently sunken, showed signs of low body weight suggesting a calorie deficit in Williams.