According to the law of universal gravitation, all bodies are attracted to each other, and the force of attraction is directly proportional to the masses of the bodies and inversely proportional to the square of the distance between them. That is, the expression "absence of gravity" does not make sense at all. At an altitude of several hundred kilometers above the Earth's surface - where manned ships and space stations fly - the Earth's gravity is very high and practically does not differ from the gravity force near the surface.
If there was a technical possibility to throw an object from a tower 300 kilometers high, it would begin to fall vertically and with the acceleration of free fall, just as it would fall from the height of a skyscraper or from a height of human growth. Thus, during orbital flights, the force of gravity is not absent and does not weaken on a significant scale, but is compensated. In the same way as for watercraft and balloons, the force of gravity of the earth is compensated by the Archimedean force, and for winged aircraft - by the lift of the wing.
Yes, but the plane flies and does not fall, and passengers inside the cabin do not fly like cosmonauts on the ISS. During a normal flight, the passenger perfectly feels his weight, and it is not the lifting force itself that restrains him from falling to the ground, but the reaction force of the support. Only during an emergency or artificially induced sharp decline does a person suddenly feel that he is no longer pressing on the support. Weightlessness arises. Why? And because if the loss of height occurs with an acceleration close to the acceleration of gravity, then the support no longer prevents the passenger from falling - it falls by itself.
spaceref.com It is clear that when the plane stops its sharp descent, or, unfortunately, falls to the ground, then it will become clear that gravity has not gone anywhere. For in terrestrial and near-terrestrial conditions, the effect of weightlessness is possible only during a fall. Orbital flight is actually a prolonged fall. A spaceship orbiting at the first cosmic speed is prevented from falling to the Earth by the force of inertia. The interaction of gravity and inertia is called "centrifugal force", although in reality such a force does not exist, it is in some way a fiction. The spacecraft strives to move in a straight line (tangentially to the near-earth orbit), but the earth's gravity constantly "twists" the trajectory of motion. Here, the equivalent of gravitational acceleration is the so-called centripetal acceleration, as a result of which not the value of the velocity changes, but its vector. And therefore the speed of the ship remains unchanged, and the direction of movement is constantly changing. Since both the spacecraft and the astronaut move at the same speed and with the same centripetal acceleration, the spacecraft cannot act as a support against which the weight of a person presses. Weight is the force of action of the body on the support that prevents the fall arising in the field of gravity, and the ship, like a sharply descending plane, does not interfere with falling.
That is why it is completely wrong to talk about the absence of Earth's gravity or the presence of "microgravity" (as is customary in English-language sources) in orbit. On the contrary, the gravity of the earth is one of the main factors in the phenomenon of weightlessness arising on board.
One can speak of true microgravity only when applied to flights in interplanetary and interstellar space. Far from a large celestial body, the effect of the forces of attraction of distant stars and planets will be so weak that the effect of weightlessness will arise. We have read about how to deal with this more than once in science fiction novels. Space stations in the form of a torus (steering wheel) will spin around the central axis and create an imitation of gravity using centrifugal force. However, in order to create the equivalent of gravity, the torus will have to be more than 200 m in diameter. There are other problems associated with artificial gravity. So all this is a matter of the distant future.
Even a person who is not interested in space has at least once seen a movie about space travel or read about such things in books. In almost all such works, people walk around the ship, sleep normally, and have no problems with eating. This means that these - fictional - ships have artificial gravity. Most viewers perceive it as something completely natural, but this is not at all the case.
Artificial gravity
This is the name of the change (in any direction) of the usual gravity for us by applying various methods. And this is done not only in fantastic works, but also in very real earthly situations, most often for experiments.
In theory, creating artificial gravity doesn't look that difficult. For example, it can be recreated with the help of inertia, more precisely, the need for this force did not arise yesterday - it happened immediately, as soon as a person began to dream of long space flights. The creation of artificial gravity in space will make it possible to avoid many problems that arise during prolonged stay in zero gravity. The muscles of the astronauts weaken, the bones become weaker. Traveling in these conditions for months can cause some muscle atrophy.
Thus, today the creation of artificial gravity is a task of paramount importance, without this skill it is simply impossible.
Materiel
Even those who know physics only at the level of the school curriculum understand that gravity is one of the fundamental laws of our world: all bodies interact with each other, experiencing mutual attraction / repulsion. The larger the body, the higher its gravity.
For our reality, the Earth is a very massive object. That is why, without exception, all bodies around her are attracted to her.
For us, this means which is usually measured in g, equal to 9.8 meters per square second. This means that if we had no support under our feet, we would fall at a speed that every second increases by 9.8 meters.
Thus, only thanks to gravity we are able to stand, fall, eat and drink normally, understand where the top is, where the bottom is. If the attraction disappears, we will find ourselves in weightlessness.
Astronauts who find themselves in space in a state of soaring - free fall - are especially familiar with this phenomenon.
In theory, scientists know how to create artificial gravity. There are several techniques.
Large mass
The most logical option is to make it so large that artificial gravity appears on it. It will be possible to feel comfortable on the ship, since orientation in space will not be lost.
Unfortunately, this method is unrealistic with the modern development of technology. To build such an object requires too many resources. Plus, it will take an incredible amount of energy to lift it.
Acceleration
It would seem that if you want to reach g, equal to the earth, you just need to give the ship a flat (platform-like) shape, and make it move perpendicular to the plane with the required acceleration. In this way, artificial gravity will be obtained, and - ideal.
However, in reality, everything is much more complicated.
The first thing to consider is the fuel issue. In order for the station to constantly accelerate, it is necessary to have an uninterruptible power supply. Even if an engine suddenly appears that does not eject matter, the law of conservation of energy will remain in force.
The second problem lies in the very idea of constant acceleration. According to our knowledge and physical laws, it is impossible to accelerate indefinitely.
In addition, such vehicles are not suitable for research missions, since they must constantly accelerate - fly. He will not be able to stop to study the planet, he will not even be able to fly slowly around it - he has to accelerate.
Thus, it becomes clear that such artificial gravity is not yet available to us.
Carousel
Everyone knows how the rotation of the carousel affects the body. Therefore, an artificial gravity device based on this principle seems to be the most realistic.
Everything that is in the diameter of the carousel tends to fall out of it at a speed approximately equal to the speed of rotation. It turns out that the bodies are acted upon by a force directed along the radius of the rotating object. This is very similar to gravity.
So, you need a ship that has a cylindrical shape. Moreover, it must rotate around its axis. By the way, artificial gravity on a spaceship, created on this principle, is often demonstrated in science fiction films.
A barrel-shaped ship, rotating around the longitudinal axis, creates a centrifugal force, the direction of which corresponds to the radius of the object. To calculate the resulting acceleration, you need to divide the force by the mass.
In this formula, the calculation result is acceleration, the first variable is the nodal speed (measured in radians per second), the second is the radius.
According to this, in order to obtain the usual g, it is necessary to correctly combine the radius of the space transport.
A similar problem is highlighted in films such as "Intersolach", "Babylon 5", "2001: A Space Odyssey" and the like. In all these cases, artificial gravity is close to the Earth's acceleration of gravity.
As good as the idea is, it can be tricky to implement.
Carousel problems
The most obvious problem is covered in A Space Odyssey. The radius of the "space carrier" is about 8 meters. In order to obtain an acceleration of 9.8, the rotation must occur at a speed of approximately 10.5 revolutions every minute.
At the indicated values, the "Coriolis effect" is manifested, which consists in the fact that at different distances from the floor, different forces act. It directly depends on the angular velocity.
It turns out that artificial gravity in space will be created, but too fast rotation of the body will lead to problems with the inner ear. This, in turn, causes imbalance, problems with the vestibular apparatus and other - similar - difficulties.
The emergence of this obstacle suggests that such a model is extremely unsuccessful.
You can try to go from the opposite, as they did in the novel "The World-Ring". Here the ship is made in the form of a ring, the radius of which is close to the radius of our orbit (about 150 million km). At this size, its rotation speed is sufficient to ignore the Coriolis effect.
It can be assumed that the problem has been solved, but this is not at all the case. The fact is that a complete revolution of this structure around its axis takes 9 days. This makes it possible to assume that the loads will be too great. In order for the structure to withstand them, a very strong material is needed, which we do not have at our disposal today. In addition, the problem is the amount of material and the construction process itself.
In games of a similar theme, as in the movie "Babylon 5", these problems are somehow solved: the rotation speed is quite sufficient, the Coriolis effect is not significant, hypothetically it is possible to create such a ship.
However, even such worlds have a drawback. His name is moment of impulse.
The ship, rotating around its axis, turns into a huge gyroscope. As you know, it is extremely difficult to force the gyroscope to deviate from the axis due to it is important that its number does not leave the system. This means that it will be very difficult to set the direction for this object. However, this problem can be solved.
Solution
Artificial gravity on the space station becomes available when the O'Neill Cylinder comes to the rescue. To create this structure, identical cylindrical ships are needed, which are connected along an axis. They should rotate in different directions. The result of such an assembly is zero angular momentum, so there should be no difficulty in giving the ship the required direction.
If it is possible to make a ship with a radius of about 500 meters, then it will work exactly as it should. At the same time, artificial gravity in space will be quite comfortable and suitable for long flights on ships or research stations.
Space Engineers
How to create artificial gravity is known to the creators of the game. However, in this fantastic world, gravity is not a mutual attraction of bodies, but a linear force designed to accelerate objects in a given direction. The attraction is not absolute here, it changes when the source is redirected.
Artificial gravity on the space station is created using a special generator. It is uniform and equidirectional in the range of the generator. So, in the real world, if you hit a ship with a generator in it, you would be pulled to the hull. However, in the game, the hero will fall until he leaves the perimeter of the device.
To date, artificial gravity in space created by such a device is inaccessible to mankind. However, even the gray-haired developers do not stop dreaming about it.
Spherical generator
This is a more realistic hardware option. When installed, gravity is directed towards the generator. This makes it possible to create a station, the gravity of which will be equal to the planetary one.
Centrifuge
Today, artificial gravity on Earth is found in various devices. They are based, for the most part, on inertia, since this force is felt by us similarly to gravitational influence - the body does not distinguish which cause causes acceleration. As an example: a person ascending in an elevator experiences the effect of inertia. Through the eyes of a physicist, lifting the elevator adds the acceleration of the car to the acceleration of free fall. When the cabin returns to measured movement, the "gain" in weight disappears, returning the usual sensations.
Scientists have long been interested in artificial gravity. The centrifuge is most often used for this purpose. This method is suitable not only for spacecraft, but also for ground stations in which it is required to study the effect of gravity on the human body.
Study on Earth, apply in ...
Although the study of gravity began from space, it is a very terrestrial science. Even today, achievements in this area have found their application, for example, in medicine. Knowing whether it is possible to create artificial gravity on the planet, you can use it to treat problems with the motor apparatus or the nervous system. Moreover, this force is studied primarily on Earth. This enables astronauts to conduct experiments while remaining under the close scrutiny of doctors. Artificial gravity in space is another matter, there are no people there who can help astronauts in the event of an unforeseen situation.
Bearing in mind complete weightlessness, one cannot take into account a satellite in near-earth orbit. These objects, albeit to a small extent, are affected by gravity. The force of gravity generated in such cases is called microgravity. Real gravity is experienced only in a vehicle flying at a constant speed in open space. However, the human body does not feel this difference.
You can experience weightlessness during a long jump (before the canopy opens) or during a parabolic descent of the aircraft. Such experiments are often performed in the United States, but on an airplane this feeling lasts only 40 seconds - this is too short for a full study.
In the USSR, back in 1973, they knew whether it was possible to create artificial gravity. And they not only created it, but also changed it in some way. A striking example of artificially reducing the force of gravity is dry immersion, immersion. To achieve the desired effect, it is required to lay a dense film on the surface of the water. The person is placed on top of it. Under the weight of the body, the body is submerged under the water, only the head remains at the top. This model demonstrates the low-gravity supportlessness that is characteristic of the ocean.
There is no need to go into space to feel the effect of the opposite force of weightlessness - hypergravity. During takeoff and landing of a spacecraft, overload in a centrifuge can not only be felt, but also studied.
Gravity Healing
Gravitational physics studies, among other things, the effect of weightlessness on the human body, trying to minimize the consequences. However, a large number of achievements of this science can be useful to ordinary inhabitants of the planet.
Doctors pin great hopes on studies of the behavior of muscle enzymes in myopathy. It is a serious illness leading to early death.
With active physical activity, a large amount of the enzyme creatinophosphokinase enters the blood of a healthy person. The reason for this phenomenon is unclear, perhaps the load acts on the cell membrane in such a way that it “leaks out”. Patients with myopathy get the same effect without exertion. Observations of astronauts show that in zero gravity, the flow of active enzyme into the blood is significantly reduced. This finding suggests that the use of immersion will reduce the negative impact of factors leading to myopathy. At the moment, experiments are being carried out on animals.
The treatment of some diseases is already carried out using the data obtained in the study of gravity, including artificial. For example, cerebral palsy, strokes, Parkinson's are treated by using exercise suits. Research on the positive effect of the support - the pneumatic shoe - has been practically completed.
Are we going to Mars?
The latest achievements of astronauts give hope for the reality of the project. There is experience of medical support of a person during a long stay away from the Earth. Research flights to the Moon, the force of gravity on which is 6 times less than our own, have also brought a lot of benefit. Now astronauts and scientists are setting themselves a new goal - Mars.
Before getting in line for a ticket to the Red Planet, you should know what the body expects already at the first stage of work - on the way. On average, the road to a desert planet will take a year and a half - about 500 days. On the way, you will have to rely only on your own strength, there is simply nowhere to wait for help.
Many factors will undermine the strength: stress, radiation, lack of a magnetic field. The most important test for the body is a change in gravity. During the journey, a person will "get acquainted" with several levels of gravity. First of all, these are overloads during takeoff. Then - weightlessness during the flight. After that - hypogravity at the destination, since the force of gravity on Mars is less than 40% of the Earth's.
How do you cope with the negative effects of weightlessness on a long flight? It is hoped that developments in the field of artificial gravity will help solve this issue in the near future. Experiments on rats traveling to Cosmos-936 show that this technique does not solve all problems.
The OS experience has shown that much more benefit to the body can be brought by the use of training complexes, which are able to determine the required load for each astronaut individually.
So far, it is believed that not only researchers, but also tourists wishing to establish a colony on the Red Planet will fly to Mars. For them, at least for the first time, the sensations of being in zero gravity will outweigh all the arguments of doctors about the dangers of a long stay in such conditions. However, in a few weeks they will need help as well, which is why it is so important to be able to find a way to create artificial gravity on the spacecraft.
Outcomes
What conclusions can be drawn about the creation of artificial gravity in space?
Of all the options currently being considered, a rotating structure looks the most realistic. However, with the current understanding of physical laws, this is impossible, since a ship is not a hollow cylinder. Inside it there are overlaps that prevent the implementation of ideas.
In addition, the radius of the ship must be so large that the Coriolis effect does not have a significant impact.
To control something like that, you need the aforementioned O'Neill cylinder, which will enable you to control the ship. In this case, the chances of using such a design for interplanetary flights increase, while providing the team with a comfortable level of gravity.
Before mankind manages to make their dreams come true, I would like to see in fantastic works a little more realism and even greater knowledge of the laws of physics.
A module with a centrifuge creating artificial gravity will appear on the International Space Station (ISS), the Institute for Biomedical Problems of the Russian Academy of Sciences (IBMP RAS) reported.
“We have recreated a small-radius centrifuge. This method has been shown to be promising for simulating artificial gravity ... The small-radius centrifuge is used to create artificial gravity on a transformable module currently being developed by RSC Energia,” said IBMP director Oleg Orlov.
Roscosmos has already instructed Energia to implement this project, he added. "We hope to make a model of a centrifuge on our base, to work it out, so that it can then be created on the basis of a transformable module," Orlov said. Such a centrifuge will be installed on an inflatable module, which is now being developed in Russia like the American BEAM (Bigelow Expandable Activity Module), docked to the ISS in April.
Video of an experimental sample of a short radius centrifuge:
“Even Tsiolkovsky believed that if artificial gravity was made, then many problems of medical support for space flights would be solved. In short orbital flights, it was not so in demand - the astronauts had enough to train the muscles and bone frame of an ordinary treadmill, a bicycle ergometer ... Now, when plans for deep space exploration appeared, the creation of artificial gravity became an urgent task. It can significantly supplement, or even completely replace, for astronauts exhausting physical training on board during an annual, or perhaps even longer flight.The first series of studies, in which Oleg Orlov took part, was aimed at finding out which rotating system is more comfortable for humans. For this, even a special revolving room was created.
“Here we are sitting in a room, it is spinning,” Orlov recalls. “Until a certain moment we feel good, but then we don’t want to not only perform some actions, but even talk. Eating food is out of the question, - such a strong dizziness begins. As a result of such experiments, choosing different speeds, we have developed acceptable requirements for such systems. For example, we now know that the most optimal rotation speed of such a room will be 6 revolutions a minute. Not everyone adapts to 9 revolutions, at 12, practically every one breaks down. These tests have been postponed for now - we have no task of creating a rotating spacecraft. But if necessary, we can resume research.
The most realistic, according to Orlov, for implementation already at the International Space Station turned out to be the second version of artificial gravity created by a short-radius centrifuge. A person can use it periodically, for example, 2 hours a day or spin around in it during sleep at night. The rotation time will be selected individually, depending on the duration of the space flight, the characteristics of the organism, and so on. While rotating in the chamber, the astronaut will experience the same effects as on Earth under normal gravitational conditions. This should be enough to compensate for some of the adverse influences.
By the way, artificial gravity is needed not only in space, but also on Earth. Staying in conditions of increased gravity, when the force of gravity is greater than on our planet, is beneficial in the treatment of the vessels of the lower extremities, accelerates the regeneration of bone tissue in fractures, and is effective in cases of hypertension. "
Why do you think astronauts in space experience a state of weightlessness? There is a high probability that you will not answer correctly.
When asked why objects and astronauts appear in a state of weightlessness in a spacecraft, many people give the following answer:
1. There is no gravity in space, so they weigh nothing.
2. Space is a vacuum, and there is no gravity in a vacuum.
3. Astronauts are too far from the surface of the Earth for the force of its gravity to act on them.
All of these answers are wrong!
The main thing to understand is that there is gravity in space. This is a fairly common misconception. What keeps the Moon in its orbit around the Earth? Gravity. What keeps the Earth in orbit around the Sun? Gravity. What prevents galaxies from flying in different directions? Gravity.
Gravity exists everywhere in space!
If you built a tower on Earth that is 370 km (230 miles) high, roughly the height of the space station's orbit, then the force of gravity acting on you at the top of the tower would be almost the same as on the surface of the earth. If you dared to take a step from a tower, you would rush to Earth just as Felix Baumgartner is going to do a little later this year when he attempts to jump from the edge of space. (Of course, we do not take into account the low temperatures, which will instantly begin to freeze you, or how the lack of air or aerodynamic resistance will kill you, and falling through layers of atmospheric air will make all parts of your body experience firsthand what it is like to “strip three skins And besides, the sudden stop will also cause you a lot of inconvenience).
Yes, so why does the space station or satellites in orbit not fall to Earth, and why do astronauts and their surroundings inside the International Space Station (ISS) or any other spacecraft appear to be floating?
It turns out it's all about speed!
Astronauts, the International Space Station (ISS) itself, and other objects in Earth orbit do not float - in fact, they fall. But they do not fall to Earth due to their enormous orbital speed. Instead, they "fall around" the Earth. Objects in earth orbit must move at a speed of at least 28,160 km / h (17,500 mph). Therefore, as soon as they accelerate relative to the Earth, the Earth's gravity immediately bends and pulls their trajectory downward, and they will never overcome this minimum approach to the Earth. Since astronauts have the same acceleration as the space station, they experience a state of weightlessness.
It happens that we, too, can experience this state - for a short time - on Earth, at the time of the fall. Have you ever been on a roller coaster ride, when immediately after passing the highest point ("top of the roller coaster"), when the cart is already starting to roll down, your body lifts from the seat? If you were in an elevator at the height of a one-hundred-story skyscraper, and the cable was broken, then while the elevator was falling, you would be floating in zero gravity in the elevator car. Of course, in this case, the ending would have been much more dramatic.
And then you've probably heard of the "Vomit Comet" airplane - the KC 135 airplane that NASA uses to create short-term zero-gravity states, to train astronauts, and test experiments or equipment under zero-G conditions. , as well as for commercial flights in zero gravity, when the plane flies along a parabolic trajectory, like in a roller coaster ride (but at high speeds and at high altitudes), passes through the top of the parabola and rushes down, then at the moment the plane crashes, conditions are created weightlessness. Fortunately, the plane exits the dive and straightens out.
However, let's get back to our tower. If instead of the usual step from the tower you made a running jump, your forward energy would carry you far from the tower, at the same time, the force of gravity would carry you down. Instead of landing at the base of the tower, you would land at a distance from it. If you increased your speed while taking off, you would be able to jump further from the tower before reaching the ground. Well, if you could run as fast as the space shuttle and the ISS orbit around the Earth, at 28,160 km / h (17,500 mph), then the arc of your jump would circle the Earth. You would be in orbit and experience a state of weightlessness. But you would fall without reaching the surface of the Earth. True, you would still need a spacesuit and a supply of breathable air. And if you could run at about 40,555 km / h (25,200 mph), you would jump straight out of the Earth and start orbiting the Sun.
