Microgravity

 

_{MICROGRAVITY:}

DEFINITION: 

As micro means very small so the definition of microgravity can be stated as:

              “Microgravity is a condition when gravity appears to be very little.”

EXPLANATION:

To understand microgravity, one should have good concepts of zero gravity and weightlessness.

Q. What is zero gravity?

“The condition in which the net gravitational force is equal to a null vector is called ZERO GRAVITY”. There is no part in the universe and on earth where there is no gravity. One may think that there is a point on earth where there is no gravity and that is the CENTER of earth. It’s fine to say that at the center of the earth gravity is zero but in reality, the net effect of the force is zero i.e., at the earth’s center gravity is present but human beings cannot detect it. Let us discuss this concept in detail.

Q. Why there is zero gravity at the center of the earth?

What if you pull a car towards yourself and at the same time your twin brother pulls it towards himself with the same force? As a result, the car will remain at the center and both of you won’t be able to get it. This does not mean that no one of you is trying to get the car instead it means that both of you are trying to get a single car. Why is it happening? It is happening because the car can only take one way. In our situation, it has two equal paths to move, which is impossible. Therefore, the car prefers to stay in the same place where it was.

The same is the situation at the earth’s center. Both the hemispheres of earth exert equal forces toward any object placed at its center due to which the object does not move. This is not because the hemispheres of the earth do not exert any gravitational pull on the object instead, they are of the same magnitude and opposite direction which cancels the effect of the resultant force. Therefore, the resultant vector of these two forces is a null vector.

CONCEPT OF MICROGRAVITY IN SPACE:

 In fact, in space there is gravity. Sounds awkward right? But it’s true. According to scientific studies and theories, there is an insignificant effect of gravitational force that makes one feel that there is no gravity. However, being more accurate one should say this negligible effect of gravity is MICROGRAVITY.

MICROGRAVITY AND WEIGHTLESSNESS:

Here, I want to make it clear that microgravity is not equal to weightlessness. Weightlessness can be experienced as a result of microgravity i.e., microgravity is a condition and weightlessness is its effect. The idea behind weightlessness is that the weight of the body becomes zero in the presence of gravity or microgravity. For instance, if a body is freely falling then at that moment, acceleration due to gravity “g” becomes zero. Therefore, weight which is the product of mass and gravitational acceleration also becomes zero. Hence, in this manner weightlessness is experienced on earth as well.    

1.    EFFECTS OF MICROGRAVITY ON ASTRONAUTS:

(i)               Difficulty in Eating, Drinking, And Other Activities:

As we have discussed earlier that due to microgravity weightlessness is experienced. In the situation of microgravity, persons or things appear to be weightless. It does not make a huge difference on planet earth. However, moving out of the earth, and going to space, took a lot of effort and studies to manage weightlessness. Due to weightlessness astronauts find it difficult to eat and drink. They cannot wash their mouths and brush their teeth properly. Going to the bathroom is quite difficult. They cannot cry there because when they cry the water bubble remains in front of the eye and it has to be dropped out by the man himself. You can see a man showing an experiment for tears at space. Go check this video below: 

 And this is just a glimpse. Astronauts cannot even sleep in space. Can you think why? It is because of microgravity. On earth, human beings are always in a state of work due to gravity. Since gravity exerts a force on us that makes us tired and due to this tiredness, we fall asleep. But in space things are changed because of microgravity. Since the work done by astronauts is very less, therefore, they cannot sleep there. The amount of work done by astronauts can be clearly understood by the fact that due to microgravity a female astronaut named Suni Williams could move equipment that weighs more than 700 pounds on earth.

This news was published by NASA on its website.

(ii)            Effects on bones:

Our bodies experience significant physiological changes on the International Space Station (ISS) owing to microgravity. We age significantly faster as compared to the earth. On Earth, we normally lose roughly 1% of our bone mass every year as we age. However, in space, we can lose up to 1.5% every month! Fortunately, when astronauts return to Earth, they restore a significant amount of bone mass. However, we know very little about how this may have influenced our bone strength. Scientists are researching this topic and investigating changes in bone mass, structure, and strength. They are employing a new 3D imaging technique that allows them to see bone structure and density in high detail. Astronauts have their forearms and legs examined before and after their voyage to the International Space Station. These 3D pictures will help scientists better understand astronauts' bone health, both in space and during their recovery period on Earth. Because the effects of microgravity on our skeletons are identical to what occurs to us as we age on Earth.

(iii)          Effects on Vision:

In microgravity, our biological fluids behave differently, and when these liquids pool and flow towards the top of the body, they can produce swelling in the chest and face, putting pressure on the optic nerve and causing eyesight to decrease. Chronic fluids may flow towards the skull during spaceflight, changing the structure of the eyes. When they return to the gravity of Earth, these anomalies may take up to a year to settle. Some alterations to the eye never fully return to their pre-spaceflight state.

(iv)          Effects on Heart:

Microgravity has a significant influence on the human heart as well because, without the continuous pull of gravity, the heart can pump blood far more effectively than it does on Earth. As a result, the heart may contract by as much as 27% since it has to work less hard to complete its function. As a result of microgravity, the shape of the heart changes from oval to round.

(v)            Effects on Muscles:

Astronauts get weaker and less coordinated as a result of their exposure to lower gravity while in space. During lengthy missions, muscle growth and function may decrease by as much as 20–40% if regular exercise is not taken.

(vi)          Effect on height:

Living in microgravity may cause you to grow up to three percent taller, which is a less concerning side effect of space flight. Though in just a few months, your height will return to normal. After spending over a year on the International Space Station, astronaut Scott Kelly came back to Earth in 2016. But he had grown 2 inches taller by the time he returned. Despite all the difficulties of space flight, one advantage is that you grow taller. On Earth, gravity is compressing your spine. Therefore, when you enter a microgravity environment and there are no longer any compressive pressures on the spine at all, it expands and grows taller by around an inch or two.

(vii)        Effect on Human Cells:

Microgravity can alter the cellular structure and gene expression in cells and tissues, which can have several impacts on development, such as the death of the embryo, failure of neural tube closure, or severe malformations of the newborn or hatchling’s general appearance. Cells under microgravity undergo morphological, cytoskeletal, and functional alterations in experiments. Studies on microtubules under gravity have revealed that they are gravity-sensitive, and changes in the cytoskeleton have been seen.

EFFECT OF MICROGRAVITY ON OBJECTS’ ROTATION:

Due to microgravity, the rotation of objects in space is quite interesting. When an item has numerous axes but one of them does not line up with the axis of rotation, the movement is intriguing. The same phenomenon can be observed with tennis rackets performing this function on Earth, it is also known as the "tennis racket theorem." The phenomenon was identified in orbit in 1985 by Russian cosmonaut Vladimir Dzhanibekov.

EFFECTS ON WATER:

Water in space behaves differently. Surface tension and capillary flow can be harnessed to move fluids in more efficient ways. What looks like fun could help us improve systems for moving fluids in microgravity, in things like fuel tanks for space travel.

CAN MICROGRAVITY BE FOUND ON EARTH?

Microgravity may be observed on Earth for the same reason it is present in orbit. For brief periods, NASA produces microgravity using aircraft. This is accomplished by the aircraft flying in parabolas that rise and fall. People and items within the aircraft are in free fall for periods of 20 to 30 seconds during the parabola's peak. A person might even temporarily experience free fall when traveling over a significant slope, much as on a roller coaster, for the same reasons. In amusement park free-fall rides, microgravity may also be felt. To explore microgravity, NASA also used drop towers. From the top of these huge towers, items are dropped with the aid of specialized equipment, falling freely.

WHY IS IT ESSENTIAL TO STUDY MICROGRAVITY BEFORE GOING TO SPACE?

To understand what happens to humans and equipment in space, astronauts investigate microgravity. The human body is impacted by microgravity in a variety of ways. Living on the space station requires astronauts to spend months in zero gravity. Additionally, the journey to and from Mars would take months in microgravity for astronauts. To keep themselves safe and healthy, they educate themselves on the impacts of microgravity. Furthermore, a lot of things appear to behave differently in microgravity. Fire burns in many ways. Flames are rounder when gravity is absent. Crystals develop more readily. Their forms are more precise when there is no gravity. In microgravity, several scientific investigations are carried out. Astronauts benefit from these experiments by learning things that would be challenging or perhaps impossible to learn on Earth.