Since the poster raised this question due to the influence of science fiction movies, it is necessary for us to examine in detail how the idea of ??a circular spacecraft simulating gravity by centrifugal force was proposed. First question: Who "invented" the use of a circular spacecraft to simulate gravity?
For those who like science fiction, "Arthur Charles Clark" is a very familiar name. It is what Mr. Liu Cixin calls "can only be parodied" and one of the three giants in the golden age of science fiction. The idea of ??using a circular spacecraft to rotate to simulate gravity first came from his novel "2001: A Space Odyssey".
Clark is not only an excellent and prolific science fiction writer, but also an outstanding scientist and theorist. Not only does he have profound scientific knowledge, but he also has a keen foresight on the development and application of science and technology. In the 1940s, the theoretical model of modern satellite communications proposed was surprisingly consistent with the development of the modern communications industry. In order to pay tribute to this great scientist and theorist, the International Astronomical Union also specifically named the geostationary orbit the "Clarke orbit". In addition, the space elevator idea also came from his imagination.
Clark's works are almost all hard science fiction works, and the descriptions of technical details are extremely detailed. In particular, "2001: A Space Odyssey" was specially created for the filming of the famous director Kubrick's film. The description of the details of aerospace can even be regarded as an authoritative aerospace textbook. The idea of ??using the centrifugal force generated by the rotation of a circular spacecraft to simulate gravity is almost a genius idea. Not only did it profoundly influence the creation of science fiction in later generations, but it also had a profound impact on aerospace scientific research. Second question: Why isn’t the space station built like a circle in science fiction movies, using centrifugal force to simulate gravity?
Just like the original poster said, in today’s space stations or spacecrafts, astronauts going to the toilet is an extremely laborious, complicated, and even dangerous task. A little carelessness may lead to accidents. ACCIDENT. Making the spacecraft into a circle and relying on rotation to generate centrifugal force is the most perfect and simplest solution to this problem. So why don't humans adopt such a solution?
First, there is the cost issue: The rotation of the spacecraft generates centrifugal force to simulate gravity. Usually, such a spacecraft must be built very huge. With the carrying capacity of today's chemical rockets, building such a huge spacecraft would require thousands or even tens of thousands of launches, which would require astronomical investments.
According to data from NASA in the early years, the price of transporting 1 pound of water (about one kilogram) to the International Space Station is approximately US$9,000 to US$40,000. How much would it cost to send such a big guy into space? Of course, with the advancement of aerospace technology in recent years, the cost has dropped to a certain extent. But as long as human spaceflight still uses the extremely primitive method of chemical rockets, it is impossible to achieve a qualitative reduction in this cost.
Second, it is a technical problem: It is impossible for such a huge spacecraft to be manufactured on the earth and then transported to space, because humans do not have such a large rocket. The most powerful rocket ever built by mankind, the Saturn V's low-Earth orbit carrying capacity is only about 120 tons, which is far from meeting the needs of launching this behemoth. But if it is not manufactured on the ground and transported to space in batches in the form of parts and then assembled, even if humans can afford such a huge launch cost, they will not be able to accurately weld and assemble in space.
Third, the issue of needs: This is actually a fundamental issue. Such giant space stations are usually used for interstellar immigration or interstellar voyages. But at this stage, there is no irreversible disaster on our home planet, Earth, and humans do not need to escape from the Earth. As of today, the speeds of Voyager 1 and 2, which are the fastest spacecrafts launched by humans compared to the sun, are only more than ten kilometers per second, less than one ten thousandth of the speed of light. This is still using data. In the case of subgravity slingshot acceleration, therefore, with today's human technological level, human beings are not capable of interstellar voyages. Only carrying out detection activities around the earth does not require building such an expensive and complicated space station.
The third question: At what level of technology will humans be able to build such a circular space station?
To build such a space station, humans need to overcome at least three major technical problems: "transportation, assembly and power".
First of all, transportation. Only by manufacturing low-cost equipment for entering space, such as space elevators, can humans transport the parts of the space station to space in batches. Secondly, there is the issue of assembly. Only by having a true space factory can humans produce, process, assemble, and manufacture such large and complex equipment in space.
Finally, there is the issue of power, that is, what kind of power does the space station use? Such a huge spacecraft consumes huge amounts of energy whether it is rotating or sailing. Although in theory, nuclear fission power generation can be sufficient even without using nuclear fusion technology that is still under development. But how to generate electricity in space without air? What kind of fuel to use... still faces many problems. From the perspective of the development of modern science and technology, only when plasma electric propulsion technology matures and can accelerate the space station to the speed of light range, reaching about 1%, will it make sense to create such a space station. Dedicated to science, science fiction, and depth, friends who like science fiction are welcome to pay attention to: Deep Science Fiction!
Human physiological structure has evolved to adapt to the environment of the earth. Astronauts who have been in the low gravity environment of space for a long time will have adverse effects on their body functions. The most obvious is muscle atrophy. The low gravity environment will also have an impact on blood circulation, causing excessive blood concentration in the head. Increased intracranial pressure can affect vision, which can be fatal to an astronaut's work.
Picture: Using elastic ropes to simulate gravity exercises on the International Space Station to prevent muscle atrophy
In order to reduce these symptoms, astronauts on long-term space missions will Use various methods to exercise muscles and prevent muscle loss. However, these methods have limited effect. After astronauts return to Earth, they still need the support of others, and it will take several weeks before they can regain the ability to walk. Is there any way to create artificial gravity?
Of course, there is a way to simulate gravity by rotating the spacecraft to create an acceleration similar to the earth's gravity acceleration.
If the radius of rotation is too small, a faster rotation speed is required, which will increase the Coriolis force due to inertia. Too much Coriolis force can cause astronauts to feel dizzy. Therefore, the radius of the spinner that generates one-third of the Earth's gravity acceleration needs to be at least tens of meters.
Picture: Artificial Gravity Space Station
In fact, we humans can already build such a space station. However, this is not necessary yet. The reasons are as follows:
First: Such a huge space station requires a lot of capital investment, and assembly is also very difficult;
Second: The reason why humans build space stations is to use space Use medium and low gravity environments to carry out some experimental work that is impossible to achieve on earth.
Of course, when humans need to carry out space missions that last for months or even years (landing on Mars, etc.), they will need spacecraft that can create artificial gravity.
Picture: Imagination of spacecraft for space colonization
Picture: Navigator space station in "The Wandering Earth"
Human beings The physiological structure of the human body evolved to adapt to the environment on Earth. The low gravity environment of astronauts in space for a long time will have a negative impact on their body functions. The most obvious is muscle atrophy. The low gravity environment will also have an impact on blood circulation, causing excessive blood concentration in the head. Increased intracranial pressure can affect vision, which can be fatal to an astronaut's work.
Picture: Using elastic ropes to simulate gravity exercise on the International Space Station to prevent muscle atrophy
In order to alleviate these symptoms, astronauts on long-term space missions will use various methods to exercise muscles. Prevent muscle loss. However, these methods have limited effect. After astronauts return to Earth, they still need the support of others, and it will take several weeks before they can regain the ability to walk.
Is there a way to create artificial gravity?
Of course, there is a way to simulate gravity by rotating the spacecraft to create an acceleration similar to the earth's gravity acceleration.
If the radius of rotation is too small, a faster rotation speed will be required, which will increase the Coriolis force due to inertia. Too much Coriolis force can cause astronauts to feel dizzy. Therefore, the radius of the spinner that generates one-third of the Earth's gravity acceleration needs to be at least tens of meters.
Picture: Artificial Gravity Space Station
In fact, we humans can already build such a space station. However, this is not necessary yet. The reasons are as follows:
First: Such a huge space station requires a lot of capital investment, and assembly is also very difficult;
Second: The reason why humans build space stations is to use space Use medium and low gravity environments to carry out some experimental work that is impossible to achieve on earth.
Of course, when humans need to carry out space missions that last for months or even years (landing on Mars, etc.), they will need spacecraft that can create artificial gravity.