Human beings have been fascinated with space since ancient times when certain astrologers studied sky bodies including stars. With advancement in technology, they started travelling in the outer space at the dawn of 20th century. More research saw humanity landing the first man on the moon in 1969. Since then, human beings have continued to explore the space with the view of staying and working there. The latest effort was the landing of NASA spaceship named Curiosity Rover on Martian land. These historical landmarks in space have heralded the need to study how human beings adapt to space. However, the challenge has always been associated with physiological changes resulting from conditions in space that long-term space travelers experience on themselves. Evidently, space environment is completely different from the one on Earth, thus those who have travelled in outer space have had to deal with the challenge of adapting to this new environment, given the high radiation level and dustiness in the outer space. This paper explores how human beings adapt to space given that its conditions differ from those in their usual environment.

According to Stuster (2011), human adaptation to space is the most important function of the human body relevant for space travelers. Sophisticated equipments may be invented for cosmonauts to protect them from harsh space conditions, but if their bodies fail to adapt to numerous physiological changes, chances of surviving long period in space are minimal. However, the body of a human being adapts marvelously to the conditions in space albeit with some short and long-term effects on persons when they return to Earth. This paper describes some of the adaptive mechanisms that space travelers experience and the effects of this adaption.

Human Adaptability to Space

Terrestrial environment is one of the most hazardous environments that man has ever ventured. From the low pressure to where they are exposed to radiation, terrestrial environment requires a number of readjustments of physical and physiological functioning of the body of a human being that is in space for a long period. Despite bone and muscle adjustments and psychological disorientation, human beings are expected to adapt to various conditions while in space (National Aeronautics and Space Administration, 2012).

Adaptation to Gravity

One of the most widely acknowledged impact of space excursion is the effect of weightlessness, also known as microgravity effect. The outer space has different force of gravity, which is completely absent. This crucial natural phenomenon is always taken for granted by people while on Earth. However, in the absence of gravity forces, people in space need to adapt to changes that occur in their body systems if they are to remain in space for a long period. An interesting fact is the role gravity forces play in maintaining the sense of balance that helps people from Earth to have a sense of motion and direction. This force combined with senses of hearing and seeing regulate the flow of information into the brain thus regulating posture and balance on Earth. In addition, weightlessness cause a distribution of body fluid from the lower limbs into the neck and face causing astronauts to experience a continuous cold flu that is caused by concentration of the body fluid in the neck and face. Other consequences of fluid redistribution are bulging veins on the neck, sinus and nasal congestion, and puffy face.

In space human beings adapt to new environment where there is no force of gravity. Even after going through a series of readjustments, including headaches, nausea, and vomiting astronauts still experience a condition known as Space Adaptation Syndrome. The mechanism behind Space Adaptation Syndrome involves the brain to ignore a series of signals from the inner eye, which are considered by the brain as confusing, as it learns to depend on sight and hear as main source for balance information.

Thus, with time, the brain comes to accept that the feet are always pointing downwards, even though this may not be true. Astronauts and cosmonauts returning to Earth must, therefore, readjust to the normal environment through an equally painful process that takes weeks. Some of adaption processes of travelers in terrestrial environment are reported to take several years. Many space travelers feel the urge for weightlessness in their brains so that they can release an object mid air.

Degradation of Bones and Muscles

Another human adaptive process is the degeneration of bones and muscles due to lack of weight. Bone and muscle have the primary function of supporting the body against the effects of gravity. In space where gravity is zero or greatly reduced, the bones and muscles loose their function, thus become degenerative in the rate of 1% every month (European Space Agency, 2012). Degenerated bones become concentrated in the body through calcification process. This may lead to kidney stones and other health problems. In addition, a lack of gravity force leads to an expansion in the spinal column that can result in backache and problems with back nerves. However, bone and muscle degeneration in space serves as a peripheral benefit to because they can walk around easily in their spaceships without body resistance.

Psychological Effects

Similarly, space adaptation requires human beings traveling in space to put up with psychological changes that involuntarily occur in the brain. Psychological changes occur when astronauts start feeling a strong sense of confinement despite their high level of preparation. As such, Barratt & Pool (2008) observe that astronauts experience desolation, which they do not have a control over. This, as it has been admitted by returning astronauts, presents necessary condition for murder, which means that astronauts start having a feeling about murder or suicide when they are in space. However, this psychological change goes through three phases that allow astronauts to adapt to their new environment coupled with fatigue, low motivation, hypersensitivity, nervous strain, and irritation.

Nevertheless, lower workloads together with recurrent opportunities for private communication with family members have been instrumental in boosting the psychological morale of astronauts. Psychological effects in the body of astronauts include enormous stress together with anxiety, insomnia, and depression. All these effects are caused by the changing environment. However, statistics indicate that most astronauts develop resistance to stress. After a short period in space they develop coping mechanisms against these feelings and after some time they stop bothering their normal functioning (National Aeronautics and Space Administration, 2012).

Olla (2009) claims that effects of living in space on psychological wellbeing were not studied in depth. Analogies on Earth, however, do exist. These include Arctic research stations and submarines. Due to stress and adaptations of the body to other environmental changes, the crew can experience depression, insomnia, and anxiety. Notably, astronauts seem to be affected more by interpersonal issues such as problems with family members than with environmental factors in space. Therefore, there is a need to conduct a research to determine this influence. Researches to determine the effect of isolation and strange environment still continue in Mars Arctic Research Station and Mars Desert Research Station. These studies will be influential in providing scientific data for improving services to crews traveling in space.

The impact of reduced pressure and radiation on the health of human beings can be devastating if their bodies do not find a proper defense mechanism. Since there is no need for autonomic reaction in the body as a mechanism of maintaining given blood pressure, the distribution of fluid is even around the body. This leads to reduced plasma with around 20% less water fluid. A reduction in water fluid initiates a number of effects that can impact the normal functioning of the body upon returning on Earth. One effect is the inability of returning astronauts to stand without assistance for more than 10 minutes without fainting. This is caused mainly by changes in autonomic regulation of blood pressure coupled with the lost plasma fluid. Brinckmann (2007) observes that the intensity of plasmid effect increasingly becomes worse as astronauts spend more time in space, even though this is neutralized in few weeks after returning to Earth. 

Declining Immune System

Human beings travelling in space also experience a decline in their immune system. This is mainly caused by the decrease in production of red blood cells and white cells that makes the body less able to protect itself against germs. In such cases, any kind of infection among them can spread very first and can be fatal if necessary measures are not taken quickly. A major cause of decrease in the body immunity is the high level of radiation that ultimately creates chromosomal aberrations in lymphocytes of the blood used by the immune system of the body. Immunodeficiencies among astronauts facilitate the spreading of infections, especially when crews are confined in a small area. In addition, high level of radiation exposure contributes to occurrence of cataracts among astronauts travelling in space. The preventive measure is to use protective shielding such as space suits as well as to use special drugs.

Loss of Taste

Similarly, astronauts travelling to space have reported cases of loss of taste. They no longer enjoy their meals and do not feel the usual taste of those meals. However, Zhang (2001) observes that some psychological and mechanical influences are thought to be the cause of the change in taste of food rather that the effect of space. However, research on this topic is still underway. For instance, it is thought that loss of food taste in space is totally psychological because the brains of astronauts or cosmonauts are aware of the unusual environment. Therefore, they refuse to engage taste zones in usual way as it is engaged in other important things like dealing with weightlessness. Food degradation may occur because of stellar radiation that can result in the breakdown of chemical composition of food thus making it taste bad.


In conclusion, human adaptability to space is an area that is still undergoing research given the fact that humans are now more interested in traveling and working in space than ever before. The improvement in scientific and medical research will help in analyzing how human beings adapt to harsh terrestrial environment and explain how cosmonauts like the Russian Valeri Polyakov could survive 438 days in space, while other astronauts seem to fall to the effects of unfriendly environment much faster.

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