The Physical Effects on The Human Body During Space Exploration

Humans, since the dawn of time, have been interested in what lies outside of Earth. People were curious what zero gravity would feel like, and what it would do to the human body. Valerie Neal, curator and chair of space history at the Smithsonian National Air and Space Museum, said, “All those normal things that we take for granted, nobody was sure quite what would happen” (Smithsonian). In the beginning scientists sent simple organisms such as mice, dogs, and monkeys into space. Now, scientists are able to send actual living people to the moon and beyond because of the study of space exploration.

After John Glenn became the first person to orbit Earth and Neil Armstrong set foot on the moon, there was a new insight to what space did to the human body, and there became new inventions in space medicine. Space medicine is the development of technologies designed to keep astronauts alive and healthy in space and the medical experiments that are performed in orbit to take advantage of the unique environment in space (Leslie). They realised that astronauts can lose bone mass, they can have heart and circulatory troubles, and brain function may decrease. These are justs some of the negative effects thats space can have on the human body.

The human skeletal system is the main support system, it stores key nutrients, makes blood, and protects many vital organs. In space, astronauts are susceptible to loss in bone mass. This may not be too much of a problem while in space, but upon return to Earth, there could be higher risk of fractures and breakage. When astronauts journey into space, the weight that their bones support is reduced dramatically. This causes their bones to weaken and start to deteriorate. There is a noticeable change when the calcium stored in bones starts to be released into the bloodstream when the bones are not being used as usual. This phenomenon is similar to the disease osteoporosis that people experience on Earth when they do not use their muscles and bones properly.

The most undeniably present change in bone mass is in between two to five months in space. Some astronauts on spacecraft Mir, have lost as much as 20% of their bone mass (Dunbar). John Uri, a mission scientist for the shuttle-Mir cooperation program, figured out that the spine, legs, and hips tend to lose more bone mass than any other parts. (NBC, 1998) To this day, we still do not know the exact cause for the osteoporosis upon return from space. Fortunately multiple scientists, from the United States and Canada, have elaborated and concluded that the best way to keep the majority of their bone mass intact is to do weight bearing exercises such as walking, jogging, volleyball and basketball (Canadian Space Agency). These recreational activities can also raise heart rate, keep the heart working and blood pumping strongly.

The heart and circulatory system is another large factor in keeping people alive and well in space. Staying in space for prolonged time periods can cause cardiac problems upon return to Earth. In space, the heart actually physically changes shape. On Earth, the heart is more of an oblong oval, and when in space, it becomes more of a sphere after some time. "The heart doesn't work as hard in space, which can cause a loss of muscle mass.

That can have serious consequences after the return to Earth, so we're looking into whether there are measures that can be taken to prevent or counteract that loss," study leader Dr. James Thomas, Moore Chair of Cardiovascular Imaging and Lead Scientist for Ultrasound at NASA, said in a statement. Shockingly, the heart becomes rounder by almost 10% (Cleveland Clinic). These changes are temporary, but can still cause problems in the future. When astronauts return to Earth, they may experience dizziness, loss of blood pressure, fainting and irregular heartbeats. These changes to the heart’s function can slow or even stop blood flow to certain parts of the body. These consequences of space travel on the heart can be very damaging to the vital organs, especially the brain.

The human brain is one of the most important parts of our body. Without proper function of the brain, we would not be able to communicate, have basic motor skills, and do basic day to day tasks. A study was conducted to see how the brain reacts to different durations of time in space. A group of 34 astronauts went into space, 18 staying for roughly six months and 16 going for about two weeks. Almost all of the astronauts who attended the six month space program had their brains shift upwards in their skull, causing their cerebrospinal fluid to thin out at the top of the skull.

The cerebrospinal fluid is a protector of the brain, spinal cord, and both of their coverings. (Gohd) This fluid also helps to decrease risk of concussion and other brain injuries. Also, 94% of the long duration astronauts had narrowing of the brain's central sulcus, a groove near the top of the brain that separates the frontal and parietal lobes. Roughly 19% of the short duration flight occupants had this narrowing occur. (Rettner) Another issue with the brain and space travel is the high pressures that are put on the brain that may cause inflammation of the optic nerve and swelling of the eye’s optic disk. Thus, these things may cause impaired vision upon return to Earth.

Conclusion

All of these consequences bring along the question: Could astronauts really survive 40 to 50 years in space with these conditions? There has been so many new inventions and tools to help astronauts become safer in space. All of the men and women working so hard to keep our scientists and researchers safe, need a round of applause. Scientists and researchers have concluded that increased activity is a major factor of reducing, or completely eliminating some of these diseases.

However, even after all of this research and discoveries, are we doing enough to see the results of having so many diseases caused from space travel. Dr. Donna Roberts, an associate professor of radiology at MUSC, said “Exposure to the space environment has permanent effects on humans that we simply do not understand. What astronauts experience in space must be mitigated to produce safer space travel.” The human race still has a lot to learn about the effects of space travel on the human body for the heart, bones, brain and other organs.