Weightlessness is the state reached when gravitational forces no longer exert influence . The term is also used to describe the characteristic or condition of weightlessness (not subject to gravity).
The attraction of bodies according to their mass is known as gravitation or gravity . Due to this natural phenomenon, those elements with mass attract each other: when the effects of gravity disappear, weightlessness occurs.
Weightlessness is usually associated, therefore, with the lack of attraction towards the Earth . If the effects of gravity are neutralized, bodies float without a defined orientation.
In short, when something is in free fall it experiences weightlessness. It is important to mention that free fall is understood as the movement made by a body when it is under the exclusive influence of a gravitational field.
Astronauts in orbit are weightless: they feel free fall constantly. This is because the ships or special stations orbit at a certain inclination and at a constant speed that allows them to always remain at the same distance from our planet thanks to the fact that the centrifugal force is balanced by gravitation.
When placed in a weightless situation, the body suffers various disorders because it is forced to adapt the functioning of its systems . In the long term, weightlessness causes the loss of muscle and bone tissue and threatens cardiac function. That is why astronauts must perform a special exercise routine.
It is important to note that physiological functions are not significantly altered by the state of weightlessness. Despite the various changes that the body is going through, it is not a particularly harmful situation, at least in the short term. Without a doubt, among the most radical changes is the sense of orientation.
When we find ourselves touching the ground, in order for us to orient ourselves naturally, the action of very small calcium deposits known as otoliths is necessary, which are found in the humor that fills the semicircular canals of the inner ear. In a state of weightlessness, on the other hand, these do not fulfill their function and then the person suffers symptoms such as nausea, vertigo and others that are associated with common dizziness.
This does not mean that astronauts go through these and other discomforts, since they have hundreds of hours of training to adapt their bodies to the changes that traveling to outer space entails. It is important to note that the physical and mental preparation they receive is probably the strictest in the world, since it exceeds even that of the divers, which - incidentally - is included in the program.
Weightlessness can cause moderate muscle atrophy, as well as a decrease in bone matter and demineralization when it lasts for a long time. This consequence is not so evident in a superficial observation, which is why medical checks after an expedition are so important.
During the first day in a state of weightlessness, the so-called space adaptation syndrome is very common. The intensity depends on the characteristics of each organism, and it rarely extends beyond the first twenty-four hours. Vomiting, weakness and dizziness are the main symptoms .
Another effect that weightlessness produces in our body is the displacement of fluids towards the upper area, including the thorax and head, which is seen through an increase in body volume , pulsations in the throat, loss of volume in the legs and waist and obstruction of the nasal passages.