HAZARDS DURING SPACEFLIGHT CAN AFFECT HUMAN HEALTH

Space missions present several unique challenges to human health and performance, including space radiation, unique gravity ﬁelds, living with just a small group of companions in a small space for a long time, limited resources like food and water


SPACE CAN BE RISKY
In late , the successful launch and return of the Artemis I Moon mission marked the start of a new and exciting chapter in human space exploration.Humans will soon set foot on the Moon for the first time in over years, with plans to establish outposts on the Moon surface and in lunar orbit.Going to Mars is next, and the trip to Mars may take up to years in space!Ensuring that space travelers are safe and have healthy bodies and minds is important for the success of these missions.As space travelers go further away from planet Earth, staying healthy becomes more challenging.For example, during a stay on the international space station (ISS), an astronaut developed a blood clot

INTERNATIONAL SPACE STATION (ISS)
A large spacecraft in orbit around the Earth where astronauts can work and live. in a large neck vein [ ]. Normally our bodies make blood clots, which are clumps of blood cells, to stop bleeding if there is a cut or injury.However, if a clot forms in a blood vessel it can be very dangerous because it may block the natural flow of blood needed by tissues and organs.The astronaut took images of the blood clot using an ultrasound device and sent the images to doctors on Earth, so they could form a treatment plan.The treatment plan included medications already aboard the ISS that, luckily, would not run out before the ISS was resupplied.Because of this collaboration between doctors on Earth and the astronaut in space, the astronaut was treated e ectively and arrived home safely after the mission.However, if a health event occurred during a longer mission further away from Earth, it would not be as easy to consult with doctors or get certain medications.This article will describe various health challenges astronauts will face, called spaceflight hazards, and will describe several of the most

SPACEFLIGHT HAZARDS
Hazards to human health and performance that are unique to space.important health risks posed by the hazards faced during a long trip

HEALTH RISKS
The risk of developing illnesses or unwanted changes in the body.Some health risks are important to think about for a long trip in space, like a trip to Mars. in space.

SPACEFLIGHT HAZARDS AND ASSOCIATED HEALTH RISKS
The spaceflight environment has a unique set of health hazards that space travelers must deal with.Spaceflight hazards include space radiation, gravity that is di erent from that of Earth, long periods of

SPACE RADIATION
Energetic charged particles originating from the sun and galactic supernovae remnants.
isolation and confinement, living in a small, potentially uncomfortable living space within a closed environment or ecosystem, and being a long distance from home [ ]. Importantly, space travelers will likely experience more than one spaceflight hazard at a time.It is important to understand how the combination of these hazards impacts the unique bodies and minds of every space traveler, as shown in

HEALTH RISK : CANCER AND OTHER DISEASES FROM SPACE RADIATION
Did you know there is radiation in space?Space radiation is ionizing radiation, meaning it has enough energy to break chemical bonds.

IONIZING RADIATION
Radiation with enough energy to break chemical bonds.
Space radiation is unlike any radiation found on Earth.It includes solar particle event radiation coming from the sun, and energetic particles known as galactic cosmic rays that come from outside our solar system (For more information on space radiation, read more here).Unfortunately, space radiation can damage the cells and tissues of space travelers, leading to health problems like cancer or other diseases (To learn more about studying the human health on Earth, read more here and in space, read more here).
Cancer takes many years to develop, so it is unlikely to happen during a space mission.However, cancer could occur after a mission.more severe and more di cult to treat than cancer caused by ionizing radiation on Earth.They are also trying to figure out how to prevent it.Space radiation may cause health problems besides cancer, like problems with the heart, lungs, blood vessels, gut, or immune system (to learn more about heart health in space explorers, read more here and here).Space radiation may also have e ects on the brain, causing problems with the ability to perform tasks, remember things, or learn new things (to learn more about how space radiation impacts the brain, read more here).To study the e ects of space radiation, scientists use the National Aeronautics and Space Administration's (NASA) Space Radiation Laboratory, a special facility where space radiation can be mimicked (Figure A, to learn more about studying space radiation e ects here on Earth, read more here and here).Importantly, most of the studies on the e ects of space radiation have been done in cell cultures and rodent models, so scientists are still trying to understand if these e ects would also happen in human bodies.

HEALTH RISK : EYE AND VISION PROBLEMS
Do you or does someone in your family wear eyeglasses to see better?We have known for a long time that going into space can change an astronaut's vision, so we give them several pairs of eyeglasses of di ering power to take with them.More recently, scientists have identified an eye disease that is specific to spaceflight, called spaceflight associated neuro-ocular syndrome (SANS).SANS

SPACEFLIGHT ASSOCIATED NEURO-OCULAR SYNDROME (SANS)
Eye and vision changes that may occur in astronauts during and after long-duration spaceflight missions.
includes swelling of the eye nerve and folding of one of the tissue layers of the eye.Both of these issues can make it di cult to see clearly.support this theory.Scientists are also working on studying the eyes of both men and women space travelers, to understand if SANS a ects them equally (Figure C) [ ].

HEALTH RISK : CHANGES IN THE BRAIN THAT AFFECT BEHAVIOR, MOOD, AND THINKING ABILITIES
Going to space for a long time can be pretty stressful.On a mission to Mars, space travelers will experience long periods of isolation, will be confined in a small space, and may have to go long periods of time without talking to people on Earth.These issues may cause problems with making decisions, performing tasks well, working together in a team, and handling stress.In severe cases, space travelers may feel depressed, anxious, or angry.Luckily, scientists have shown that there are habits that can reduce the stress of going to space.On the ISS, a laboratory in space where astronauts work and live (Figures C, D), sleeping well, exercising, journaling, communicating with loved ones, and thinking positively has helped astronauts reduce stress.
However, a journey to Mars will be more challenging than a mission on the ISS.Space travelers will be gone for much longer periods of time and they may not be able to communicate with people on Earth for long stretches.To study these conditions, scientists use a space analog: something that mimics the experience of traveling in

HEALTH RISK : A POOR DIET
A poor diet has always been a concern for explorers.For example, scurvy, a disease caused by a lack of vitamin C, killed many sailors between the sixteenth-eighteenth centuries.Like sailors, space travelers will also need to ensure they are eating enough healthy foods that contain the vitamins and nutrients they need to survive and thrive.However, unlike sailors, space travelers do not have the option to stop at a port city and refill their food supplies.On the ISS, scientists have been studying the importance of good nutrition and the consequences of poor nutrition, as NASA prepares for longer journeys to the Moon and Mars (Figure D) [ ]. Poor nutrition can cause many health issues, like poor bone health, reduced ability to think clearly, reduced heart function, and vision problems.Good nutrition may also help fight some of the negative health e ects caused by the other spaceflight hazards.Some health conditions on Earth may also be linked to poor nutrition, so studying how a poor diet impacts space travelers is not only useful for a trip to space-it could improve the health of people on Earth, too.

BACK TO THE MOON… AND BEYOND!
There are many hazards in the space environment that may impact the health of space travelers.These hazards may lead to a number of potential health problems.Research on space-related health risks will enable space travelers to have healthy bodies and minds on their trips to the Moon, Mars, and beyond!If you still want to learn more, and we hope you do, further information on these topics can be found on NASA's website.
Figure .Spaceflight hazards are linked to various human health risks, as shown in Figure .These include the risk of cancer or other diseases caused by space radiation, the risk of eye and vision problems, the risk of brain changes that negatively a ect behavior, mood, and thinking abilities, and the risk of a poor diet [ ].

FigureFigure
Figure Figure Scientists are working to understand if cancer triggered by space radiation is So far, SANS has not impacted how well space travelers can see before or after a mission.However, scientists are studying how SANS may impact astronauts during and after a longer trip in space, like a trip to Mars.Scientists are also trying to understand what causes SANS.One theory is that the shifting of the fluids in the body that happens in microgravity is part of the problem, though more data are needed to