Space excursion: how does weightlessness work?

We have often seen photos of astronauts,floating, for example, inside the International Space Station. What can I say - the film "Gravity" is not just "Oscar" received. Evidence that there are places where gravity is absent as such can be found everywhere. But although weightlessness looks funny, and each of us probably would not have refused the opportunity to experience it for ourselves, the human body doesn’t treat it very well. The head is buzzing and the leg muscles contract. In the long run, the muscles weaken and the bones become fragile. These effects can cause serious damage to your body, especially if you go on a long flight to Mars.

In this article we will take you aboardInternational Space Station and tell you what weightlessness does with your body, what changes can occur, and what to do to prevent or reverse these side effects.

Meet Microgravity

Imagine that you are wearing a spacesuit andlie on your back in the flight deck of the spacecraft. You lie on your back for several hours while the pilots and the flight control center are preparing to launch. Usually, when you stand straight, gravity pulls the blood down, so its entire pools gather at your feet. However, since you are lying on your back, blood is distributed in different ways in your body, including accumulating in your head, as your legs are raised. My head is a bit heavy, as if you just woke up.

Rocket engines ignite and you feelacceleration. You are being pushed into a chair as the device takes off. Gravity along with an increase in the speed of the ship increases three times (on some roller coasters you can experience this level of acceleration). Your chest is compressed, breathing becomes a little difficult. After eight and a half minutes you find yourself in space and begin to experience a completely different feeling: weightlessness.

The correct term for weightlessness ismicrogravity. You are not weightless, as earth gravity keeps you and the aircraft in orbit. You are in a state of free fall, as if you just jumped from a plane, except that you fall horizontally and never fall. Suppose you are standing on a scale, and they show your weight, as gravity pulls down both you and the scales. Since the scales are on the ground, they repel upward with equal force - and this force is your weight. But if you jump from a cliff, standing on a scale, both you and the scales will be attracted by gravity. You will not put pressure on the scales, and they will not put pressure on you. Your weight will be zero. This is Newton's law.

Since the spacecraft and all objects in itfalling with one speed - everything that is not fixed floats. If you have long hair, they will float around your face. If you pour water from a glass, it will gather into a large spherical drop, which can be broken into smaller drops. Dumplings and sweets themselves will swim into your mouth if you push them along the desired trajectory. Sitting in a chair, you will not know that you are sitting, because your body will not put pressure on the chair. If you don't hold on, you'll float away. Moreover, if you do not hold on to the wall or the floor with your hand or foot, you will not be able to budge - there’s nothing to push off of. For this reason, in any spacecraft there are always many handrails for arms and legs.

What is microgravity taste?

When you first find yourself in a state of weightlessness, you will feel the following:

- nausea;

- disorientation;

- headache;

- loss of appetite;

- constipation;

- something else…

The longer you stay in conditionsmicrogravity, the weaker your muscles and bones. These sensations will be caused by various changes in your body systems. Let's take a closer look at how the body reacts to weightlessness.

Cosmic disease

Nausea and disorientation that tastes likeSucking feeling in the stomach when the car "flies" down the track or picks you up on the carousel. Only on board the ship will this feeling last for several days. This feeling of cosmic disease, weakness of motility, when your brain receives conflicting information from the vestibular organs located in your inner ear. Your eyes see where to move up and down in the ship, but your vestibular system relies on gravity, determining directions that does not work in weightlessness. Therefore, your eyes can tell the brain that you are moving from top to bottom, but your brain will not understand. This causes disorientation and nausea, which can lead to loss of appetite and vomiting. Fortunately, after a few days, the brain adapts and begins to respond solely to visual signals. Tablets also help.

Puffy face and chicken legs

Under microgravity, your face willpuffy, and the sinuses - overloaded, which will cause headache and impaired motility. On Earth, this can be felt if you stand upside down - blood rushes to your head.

On Earth, gravity draws your blood,as a result, its significant volumes accumulate in the veins of the legs. As soon as you find yourself in microgravity, the blood will move from your legs to your chest and head. The face is swollen, and the legs, on the contrary, will decrease in size.

When blood passes to the chest, the heartincreases in size and pumps more blood with each beat. The kidneys respond to this increased blood flow by producing more urine, as if you had drunk a large glass of water. In addition, an increase in blood flow reduces the level of secretion by the pituitary gland of antidiuretic hormone (ADH), which reduces thirst. You will not want to drink as much water as on Earth. Together, these two factors will help your chest and head to get rid of excess fluid in a few days, and your body's fluid flow will normalize (for cosmic conditions). Upon returning to Earth, you will drink more and feel tired, but it will pass.

Cosmic anemia

As your kidneys remove excessfluid, they also reduce the secretion of erythropoietin - a hormone that stimulates the production of red blood cells by bone marrow cells. The decrease in red blood cell production is accompanied by a decrease in plasma volume, so the hematocrit (the percentage of the blood volume occupied by red blood bodies) is the same as on Earth. Upon returning to Earth, your erythropoietin level will increase, as will the number of red blood cells.

Weak muscles

When you are in microgravity,your body assumes the “fetus” position: you bend a little, your arms and legs also assume a semi-bent state. In this position, you do not use many muscles, especially those that help you maintain your posture (anti-gravity muscles). As you stay aboard the ISS, your muscles change. Their weight decreases, which leads to "chicken legs". Your body no longer needs muscles that are slowly contracting, like those used in a standing position. Fast-cutting fibers are needed to move faster around the station. The more you stay on the ISS, the less muscle mass you will have. The loss of muscle mass weakens you, and this, by the way, is a serious problem for long flights, especially after returning to Earth.


On Earth, your bones support your body weight. The size and weight of the bones are carefully balanced. Under microgravity, your bones no longer need to support your body, so all of your bones, especially those bearing, around your hips, thighs, and lower back, are used less than on Earth. The size and weight of bones in weightlessness are reduced by about 1% per month. As a result, they may simply collapse upon returning to Earth. It is not known what percentage of the bones to be restored after returning to Earth, but it is definitely not equal to 100. It is this problem that limits the time spent in space.

In addition to weak bones, the concentration of calcium in the blood leads to kidney disease, which needs to remove this excess calcium. Kidney stones may form.


What can be done to facilitate your stay inmicrogravity conditions? As for inanimate things, every object in a station or ship should be stored in a closet, tied or fastened to the wall with a velcro.

For example, if you eat in zero gravity,you must stand firmly on your feet, and your meal tray must be attached to you with a strap. As you know, food is usually stored in tubes and is a semi-liquid mass, some rice or pate, which can be easily squeezed out of the tube, and it will not float away. Portable equipment, like a laptop, is also tied to you or to the wall of a ship.

Let's remember that on board the ISS our bodybasically undergoes three changes: loss of fluid, loss of muscle tissue and loss of bone mass. What should be done to minimize these losses?

Fluid loss

One of the countermeasures for fluid loss isa device called the “negative pressure of the lower body” (NBT) that works like a vacuum cleaner to lower your waist while holding fluid in your legs. This device can be attached to the simulator, for example, to a treadmill. Once a day, you can exercise with ODNT for 30 minutes, maintaining the cardiovascular system in a state close to the earth.

In addition, before returning to Earth, you can drinkplenty of water or electrolyte solution to help restore lost fluid in the body. This will warn of a swoon after leaving the spacecraft.

Muscle and bone loss

NASA and Roscosmos found out that the best wayTo minimize the loss of muscle and bone mass in space - this is a permanent workout. They train the muscles, prevent their degradation and create a load on the bones, simulating weight. Every day for two hours on different equipment in special straps - and you can minimize the loss of muscle and bone mass.

However, scientists recognize that more is neededresearch to identify quality countermeasures. And both onboard the ISS and on Earth, both with the help of people and animals. Research results can pave the way for long trips, for example, to Mars.

How to simulate microgravity on Earth?

There are several human and animal models for modeling and studying microgravity on Earth.

Head tilt

The man lies down on the bed, tilting his head down.about 5 degrees from the horizontal line. The slope reproduces the displacement of body fluids that occurs under conditions of gravity. In addition, bearing bones and muscles are not used, thereby causing atrophy.

Dive into the pool

Placing the item in a warm pool with water for a long period of time. The buoyancy of water redistributes fluids in the body and facilitates the carrying bones and muscles, creating microgravity conditions.

Hanging by the tail of the rat

Rats are suspended by tails in cages for long periods of time. This situation provokes the displacement of fluids and the inaction of the hind limbs, which leads to the deterioration of muscles and bones.

Artificial Microgravity

Flying on an airplane that flies byparabolic trajectory up and down, creating 30-second periods of microgravity at each peak. NASA uses this technique to train astronauts, and also provides an opportunity for everyone to experience this sensation.