The meaning is clear: every revolution lights new stars in the sky. They are burning...
What kid doesn't dream of becoming an astronaut? However, only a few people around the world manage to realize this dream, and only very rich people can go on a private space flight. But in 2050, almost anyone will be able to get into orbit. After all Japan promises to launch the world's first elevator to space.
Among the many in space exploration, one can single out the initiative of the Japanese construction corporation Obayashi to create an orbital elevator. This vehicle, according to the authors, should appear by 2050. It promises to be the cheapest way to deliver people and cargo into space.
The elevator will move at a speed of 200 kilometers per hour along an ultra-strong and ultra-light cable leading from the earth's surface to a distant orbital station, where not only a scientific laboratory will be located, but also a hotel for space tourists, of whom there will be hundreds or even more with the advent of this type of transport. thousands of times more than exists today.
Making such bold promises Obayashi Corporation allows the development of new materials that allow you to create fibers that are a hundred times stronger than steel. And these technologies are developing every new year, every new month.
There are also annual international technical competitions, whose participants work on ideas for the implementation of a space elevator. They develop new materials and innovative technologies for the delivery of goods into orbit. At the same time, every year the ideas become clearer and more promising.
The combination of the factors described above is precisely what allows Obayashi Corporation to make stunning statements about the possibility of launching an orbital elevator by 2050.
The idea of creating a space elevator was mentioned in the science fiction works of the British writer Arthur Charles Clark as early as 1979. He wrote in his novels that he was absolutely sure that one day such an elevator would be built.
But the first person to come up with such a strange idea was the Russian engineer and founder of Russian cosmonautics Konstantin Eduardovich Tsiolkovsky. Inspired by the construction of the Eiffel Tower, he proposed building an even taller tower several thousand kilometers in height. Tsiolkovsky proposed to settle space using orbital stations, put forward the ideas of a space elevator and hovercraft.
The space elevator sounds fantastic. But people in the 19th century also would not have been able to believe in the appearance of such technological achievements as an airplane or spaceship. Obayashi Construction Corporation in Japan is already developing technical documentation for the preparation of the construction of a space elevator. The project cost is $12 billion. The construction of the facility will be completed in 2050.
The potential benefit from the use of space elevators is quite high. The thing is that overcoming the earth's gravity with the help of jet thrust is impractical. For example, it costs $500 million to launch the Shuttle just once, so launching traditional launch vehicles will become uneconomical.
A space elevator consists of three main parts: a base, a tether, and a counterweight.
A massive platform in the ocean, representing the base of the elevator, will hold one end of a carbon fiber cable, at the end of which there will be a counterweight - a heavy object that will play the role of a satellite that rotates after our planet and is kept in orbit due to centrifugal force. It is on this cable, stretched into the sky to a height of up to one hundred thousand kilometers, that cargo will rise into space.
To deliver a kilogram of cargo into space using a rocket, it takes up to 15 thousand dollars. The Japanese calculated that in order to deliver a cargo with the same weight into orbit, they would spend ... $ 100
The space elevator is a carefully crafted idea. For example, it is calculated that the cable cannot be made of steel. It will simply break under the weight of its weight. The material must be 90 times stronger and 10 times lighter than steel.
As cables, the engineers were going to use carbon nanotubes, but it turned out that it was impossible to weave cables of great length from such a material.
More recently, an invention has emerged that could finally make space elevator fantasies a reality. A team of researchers led by John Budding at the University of Pennsylvania has created ultra-thin nanowires from microscopic diamonds that are much stronger than nanotubes and polymer fibers.
The Tokyo Sky Tree is a television tower in the Sumida district, the tallest among the television towers in the world.
Yoji Ishikawa, head of the research division at Obayashi, believes that the know-how of the University of Pennsylvania is really capable of bringing humanity closer to space. He says that the new material, of course, must pass a series of strength tests, but it seems that this is exactly what he and his colleagues have been looking for.
Obayashi has already built high-speed elevators for a television tower with a height of about 635 meters
NASA is now also closely involved in the secret development of the space lift. In the future, it will be possible to deliver parts of giant interplanetary ships into orbit and assemble them in space. Such a project can only be realized with the help of a spacelift.
But the most important thing is the state, which will be the first to build space elevator, for many centuries monopolizes the sphere of space cargo transportation.
Illustration for the science fiction novel Green Mars by Kim Stanley Robinson depicting
space elevator on Mars.
The idea of an astroengineering facility to launch cargo into a planetary orbit or even beyond it. For the first time, such an idea was expressed by Konstantin Tsiolkovsky in 1895, the idea was developed in detail in the writings of Yuri Artsutanov. The hypothetical design is based on the use of a tether stretched from the planet's surface to an orbital station located in the GSO. Presumably, such a method in the future can be orders of magnitude cheaper than using launch vehicles.
The cable is held at one end on the surface of the planet (Earth), and the other - at a fixed point above the planet above the geostationary orbit (GSO) due to centrifugal force. A lift carrying a payload rises along the cable. When lifting, the load will be accelerated due to the rotation of the Earth, which will allow it to be sent beyond the Earth's gravity at a sufficiently high altitude.
The rope requires extremely high tensile strength combined with low density. Carbon nanotubes, according to theoretical calculations, seem to be a suitable material. If we admit their suitability for the manufacture of a cable, then the creation of a space elevator is a solvable engineering problem, although it requires the use of advanced developments and high costs of a different kind. The creation of the elevator is estimated at 7-12 billion US dollars. NASA is already funding related developments by the American Institute for Scientific Research, including the development of a lift capable of moving independently along a cable.
Contents [remove]
1 Construction
1.1 Founding
1.2 Rope
1.2.1 Rope thickening
1.3 Lift
1.4 Counterweight
1.5 Angular momentum, speed and slope
1.6 Space launch
2 Construction
3 Space elevator economics
4 Achievements
5 Literature
6 Space elevator in various works
7 See also
8 Notes
9 Links
9.1 Organizations
9.2 Miscellaneous
Design
There are several design options. Almost all of them include a base (base), a cable (cable), hoists and a counterweight.
Base
The base of the space elevator is the place on the surface of the planet where the cable is attached and the lifting of the load begins. It can be mobile, placed on an ocean-going vessel.
The advantage of a movable base is the ability to maneuver to avoid hurricanes and storms. The advantages of a stationary base are cheaper and more accessible sources of energy, and the ability to reduce the length of the cable. The difference of several kilometers of cable is relatively small, but can help to reduce the required thickness of the middle part of the cable and the length of the part that goes out for geostationary orbit.
Cable
The rope must be made of a material with an extremely high ratio of tensile strength to specific gravity. A space elevator will be economically justified if it is possible to produce on an industrial scale at a reasonable price a cable with a density comparable to graphite and a strength of about 65–120 gigapascals.
For comparison, the strength of most types of steel is about 1 GPa, and even for its strongest types - no more than 5 GPa, and the steel is heavy. The much lighter Kevlar has a strength in the range of 2.6-4.1 GPa, while quartz fiber has a strength of up to 20 GPa and higher. The theoretical strength of diamond fibers can be slightly higher.
Carbon nanotubes should, according to theory, have an extensibility much higher than required for a space elevator. However, the technology for producing them in industrial quantities and braiding them into a cable is just beginning to be developed. Theoretically, their strength should be more than 120 GPa, but in practice, the highest extensibility of a single-walled nanotube was 52 GPa, and, on average, they broke in the range of 30–50 GPa. The strongest filament woven from nanotubes will be less strong than its components. Research to improve the purity of the material of the tubes and to create different types of tubes is ongoing.
Most space elevator projects use single-walled nanotubes. Multi-layers have higher strength, but they are heavier, and their strength-to-density ratio is lower. Possible variant- use high-pressure bonding of single-walled nanotubes. At the same time, although strength is lost due to the replacement of the sp² bond (graphite, nanotubes) with the sp³ bond (diamond), they will be better retained in one fiber by van der Waals forces and will make it possible to produce fibers of arbitrary length. [source not specified 810 days]
Defects in the crystal lattice reduce the strength of nanotubes
In an experiment by scientists from the University of Southern California (USA), single-walled carbon nanotubes demonstrated a specific strength 117 times higher than steel and 30 times higher than Kevlar. It was possible to reach an indicator of 98.9 GPa, the maximum value of the nanotube length was 195 μm.
The technology of weaving such fibers is still in its infancy.
According to some scientists, even carbon nanotubes will never be strong enough to make a space elevator tether.
Experiments of scientists from the Technological The University of Sydney made it possible to create graphene paper. Sample tests are encouraging: the density of the material is five to six times lower than that of steel, while the tensile strength is ten times higher than that of carbon steel. At the same time, graphene is a good conductor of electric current, which allows it to be used to transfer power to the lift, as a contact bus.
Rope thickening
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A space elevator has to support at least its own weight, quite a bit due to the length of the tether. The thickening on the one hand increases the strength of the cable, on the other hand, it adds its weight, and hence the required strength. The load on it will vary in different places: in some cases, the section of the tether must withstand the weight of the segments below, in others it must withstand the centrifugal force that keeps the upper parts of the tether in orbit. To satisfy this condition and to achieve the optimality of the cable at each of its points, its thickness will be variable.
It can be shown that, taking into account the gravity of the Earth and centrifugal force (but not taking into account the smaller influence of the Moon and the Sun), the cross section of the cable, depending on the height, will be described by the following formula:
Here A ® is the cross-sectional area of the cable as a function of the distance r from the center of the Earth.
The following constants are used in the formula:
A0 is the cross-sectional area of the tether at the level of the Earth's surface.
ρ is the density of the cable material.
s - tensile strength of the cable material.
ω is the circular frequency of the Earth's rotation around its axis, 7.292×10−5 radians per second.
r0 is the distance between the center of the Earth and the base of the tether. It is approximately equal to the radius of the Earth, 6,378 km.
g0 - free fall acceleration at the base of the cable, 9.780 m/s².
This equation describes a cable whose thickness first increases exponentially, then its growth slows down at a height of several Earth radii, and then it becomes constant, eventually reaching geostationary orbit. After that, the thickness starts to decrease again.
Thus, the ratio of the areas of the cable sections at the base and at the GSO (r = 42 164 km) is:
Substituting here the density and strength of steel and the diameter of the cable at the ground level of 1 cm, we get a diameter at the GSO level of several hundred kilometers, which means that steel and other materials familiar to us are unsuitable for building an elevator.
It follows that there are four ways to achieve a more reasonable cable thickness at the GSO level:
Use less dense material. Since the density of most solids lies in the relatively small range of 1000 to 5000 kg/m³, it is unlikely that anything will be achieved here.
Use more durable material. Research is mainly in this direction. Carbon nanotubes are ten times stronger than the best steel, and they will significantly reduce the thickness of the cable at the GSO level.
Raise the cable base. Due to the presence of an exponent in the equation, even a slight rise in the base will greatly reduce the thickness of the cable. Towers up to 100 km high are offered, which, in addition to saving on the cable, will allow you to avoid the influence of atmospheric processes.
Make the base of the cable as thin as possible. It still needs to be thick enough to support a loaded hoist, so the minimum thickness at the base also depends on the strength of the material. It is enough for a carbon nanotube cable to have a thickness of only one millimeter at the base.
Another way is to make the base of the elevator movable. Movement even at a speed of 100 m/s will already give a gain in circular speed by 20% and will reduce the length of the cable by 20-25%, which will facilitate it by 50 percent or more. If you "anchor" the cable at supersonic [source not specified for 664 days] by plane or train, then the gain in cable mass will already be measured not by percentages, but by dozens of times (but losses are not taken into account for resistance air).
Lift
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Conceptual drawing of a space elevator going up through the clouds
A space elevator cannot operate like a conventional elevator (with moving cables) because the thickness of its cable is not constant. Most projects propose the use of a hoist that climbs up a fixed cable, although options have also been proposed to use small segmented movable cables stretched along the main cable.
Offered various ways lift structures. On flat cables, you can use pairs of rollers held by friction. Other options are moving spokes with hooks on plates, rollers with retractable hooks, magnetic levitation (unlikely, since bulky tracks will have to be fixed on the cable), etc. [source not specified 661 days]
A serious problem in the design of the lift is the energy source [source not specified 661 days]. The energy storage density is unlikely to ever be high enough for the hoist to have enough energy to lift the entire cable. Possible external energy sources are laser or microwave beams. Other options are the use of the braking energy of lifts moving down; difference in troposphere temperatures; ionospheric discharge, etc. The main variant [source not specified 661 days] (energy beams) has serious problems related to with efficiency and heat dissipation at both ends, although if one is optimistic about future technological advances, it is feasible.
Hoists should follow each other at an optimal distance to minimize the load on the cable and its oscillations. and maximize throughput. The most unreliable area of the cable is near its base; there should not be more than one lift [source not specified 661 days]. Lifts that only move up will increase capacity, but will not allow braking energy to be used when moving down, and will also not be able to return people to the ground. In addition, the components of such lifts must be used in orbit for other purposes. In any case, small lifts are better than large lifts, because their schedules will be more flexible, but they impose more technological restrictions.
In addition, the elevator thread itself will constantly experience the action of both the Coriolis force and atmospheric flows. Moreover, since the “lift” must be located above the height of the geostationary orbit, it will be subject to constant loads, including peak loads, for example, jerky [source not specified 579 days].
However, if the above obstacles can be somehow removed, then a space elevator can be realized. However, such a project will be extremely expensive, but in the future it may compete with disposable and reusable spacecraft [source not specified 579 days].
Counterweight
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The counterweight can be created in two ways - by binding a heavy object (for example, an asteroid) for geostationary orbit or continuation of the tether itself for a considerable distance for geostationary orbit. The second option has been more popular recently, since it is easier to implement, and in addition, it is easier to launch payloads to other planets from the end of the elongated cable, since it has a significant speed relative to the Earth.
Angular momentum, speed and slope
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When the elevator moves up, the elevator tilts 1 degree, because the top of the elevator moves around the Earth faster than the bottom (Coriolis effect). Scale not saved
The horizontal speed of each section of the cable increases with height in proportion to the distance to the center of the Earth, reaching on the geostationary orbit of the first cosmic speed. Therefore, when lifting the load, he needs to get additional angular momentum (horizontal speed).
Angular momentum is acquired due to the rotation of the Earth. At first, the hoist moves slightly slower than the cable (Coriolis effect), thereby “slowing down” the cable and deflecting it slightly to the west. At a climb speed of 200 km/h, the cable will tilt by 1 degree. Horizontal Tension Component in non-vertical the cable pulls the load to the side, accelerating it in an easterly direction (see diagram) - due to this, the elevator acquires additional speed. According to Newton's third law, the cable slows down the Earth by a small amount.
At the same time, the influence of the centrifugal force causes the cable to return to an energetically favorable vertical position, so that it will be in a state of stable equilibrium. If the center of gravity of an elevator is always above geostationary orbit, regardless of the speed of the elevators, it will not fall.
By the time the cargo reaches the GSO, its angular momentum (horizontal velocity) is sufficient to put the cargo into orbit.
When lowering the load, the reverse process will occur, tilting the cable to the east.
launch into space
At the end of the tether 144,000 km high, the tangential velocity component will be 10.93 km/s, which is more than enough to leave the Earth's gravitational field and launch ships to Saturn. If an object is allowed to slide freely along the top of the tether, it will have enough speed to leave solar system. This will happen due to the transition of the total angular momentum of the cable (and the Earth) into the speed of the launched object.
To achieve even higher speeds, you can lengthen the cable or accelerate the load due to electromagnetism.
Construction
Construction underway with geostationary stations. This is the only a place where a spacecraft can land. One end descends to the surface of the Earth, being pulled by the force of gravity. Another, for balancing, - to the opposite side by centrifugal force. This means that all building materials must be raised. to geostationary orbit in the traditional way, regardless of the destination of the cargo. That is, the cost of lifting the entire space elevator to geostationary orbit - the minimum price of the project.
Economics of a space elevator
Presumably, the space elevator will greatly reduce the cost of sending cargo into space. Space elevators are expensive to build, but their operating costs are low, so they are best used for long periods of time for very large volumes of cargo. Currently, the cargo launch market may not be large enough to justify the construction of an elevator, but the drastic reduction in price should lead to a greater variety of cargo. In the same way, other transport infrastructure justifies itself - highways and railways.
The cost of developing an elevator is comparable to the cost of developing a space shuttle [source not specified 810 days]. There is still no answer to the question of whether the space elevator will return the money invested in it or whether it would be better to invest it in the further development of rocket technology.
Do not forget about the limit on the number of repeater satellites on the geostationary orbit: currently international agreements 360 satellites are allowed - one transponder per degree of angle, to avoid interference when broadcasting in the Ku-band. For C-frequencies, the number of satellites is limited to 180.
Thus, the space elevator is minimally suitable for mass launches. to geostationary orbit [source not specified 554 days] and is most suitable for the exploration of outer space and the moon in particular.
This circumstance explains the real commercial failure of the project, since the main financial costs of non-governmental organizations are oriented to relay satellites, occupying either geostationary orbit (television, communications) or lower orbits (global positioning systems, natural resource observations, etc.).
However, the elevator can be a hybrid project and, in addition to the function of delivering cargo to orbit, remain the base for other research and commercial programs that are not related to transport.
Achievements
Since 2005, the US has hosted the annual Space Elevator Games, organized by the Spaceward Foundation with support from NASA. There are two nominations in these competitions: “the best cable” and “the best robot (lift)”.
In the lift competition, the robot must overcome the set distance by climbing a vertical cable at a speed not lower than the speed established by the rules. (in competitions In 2007, the standards were as follows: cable length - 100 m, minimum speed - 2 m / s). The best result of 2007 is the covered distance of 100 m with an average speed of 1.8 m/s.
The total prize fund of the Space Elevator Games competition in 2009 was $4 million.
In the competition for the strength of the cable, participants must provide a two-meter ring from heavy-duty material weighing no more than 2 grams, which a special installation checks for rupture. To win the competition, the strength of the cable must be at least 50% higher than the sample already available to NASA in this indicator. So far, the best result belongs to the cable, which has withstood a load of up to 0.72 tons.
The Liftport Group, which gained notoriety for its claims to launch a space elevator in 2018 (later pushed back to 2031), does not compete in these competitions. Liftport conducts its own experiments, so in 2006 a robotic lift climbed a strong rope stretched with balloons. From one and a half kilometers, the lift managed to cover only 460 meters. At the next stage, the company plans to conduct tests on a cable 3 km high.
At the Space Elevator Games competition from November 4 to 6, 2009, a competition organized by the Spaceward Foundation and NASA was held in Southern California, on the territory of the Dryden Flight Research Center, within the boundaries of the famous Edwards Air Force Base. The test length of the cable was 900 meters, the cable was lifted by helicopter. LaserMotive took the lead with a 3.95 m/s lift, which is very close to the required speed. The elevator covered the entire length of the cable in 3 minutes 49 seconds, the elevator carried a payload of 0.4 kg.
In August 2010, LaserMotive held a demonstration of their latest invention at the AUVSI Unmanned Systems Conference in Denver, Colorado. The new kind laser will help to more economically transmit energy over long distances, the laser consumes only a few watts.
Literature
Yuri Artsutanov "Into space - on an electric locomotive, newspaper "Komsomolskaya Pravda" dated July 31, 1960.
Alexander Bolonkin "Non-Rocket Space Launch and Flight", Elsevier, 2006, 488 pgs. http://www.scribd.com/doc/24056182
Space elevator in various works
One of Arthur Clarke's famous works, The Fountains of Paradise, is based on the idea of a space elevator. In addition, the space elevator is featured and in the final parts of his famous tetralogy A Space Odyssey (3001: The Last Odyssey).
Battle Angel features a cyclopean space elevator that has the Celestial City of Salem (for citizens) along with the lower city (for non-citizens) at one end, and the space city of Yeru at the other end. A similar structure is located on the other side of the Earth.
In the series " Star Trek: Voyager" in episode 3x19 "Rise" (Rise), a space elevator helps the crew escape from a planet with a dangerous atmosphere.
Civilization IV has a space elevator. There he is one of the later "Great Miracles".
IN fantasy novel Timothy Zana's "Silkworm" ("Spinneret", 1985) mentions a planet capable of producing super fiber. One of the races interested in the planet wanted to get this fiber specifically for the construction of a space elevator.
In Sergei Lukyanenko's dilogy "Stars are Cold Toys", one of the extraterrestrial civilizations, in the process of interstellar trade, delivered heavy-duty threads to Earth that could be used to build a space elevator. But extraterrestrial civilizations insisted exclusively on use them for their intended purpose - to help with childbirth.
In the anime Mobile Suit Gundam 00, there are three space elevators, they also have a ring of solar panels attached to them, which allows the space elevator to also be used to generate electricity.
In the anime Z.O.E. Dolores is present with a space elevator, and also shown what could happen in the event of a terrorist attack.
In the science fiction novel Doomed to Victory by J. Scalzi (eng. Scalzi, John. Old Man’s War), space elevator systems are actively used on Earth, numerous terrestrial colonies and some planets of other highly developed intelligent races to communicate with the berths of interstellar ships.
In Alexander Gromov's science fiction novel Tomorrow Comes Eternity, the plot is built around the fact of the existence of a space elevator. There are two devices - a source and a receiver, which, by means of an "energy beam", are capable of lifting the "cabin" of the elevator into orbit.
In Alastair Reynolds' fantasy novel The City of the Abyss, detailed description buildings and functioning space elevator, the process of its destruction (as a result of a terrorist attack) is described.
Terry Pratchett's fantasy novel The Strata features "The Line", an extra-long artificial molecule used as a space elevator.
Mentioned in the song of the group Sounds of Mu "Elevator to the sky"
A space elevator is mentioned in the anime series Trinity Blood, in which the spaceship "Arc" serves as a counterweight.
At the very beginning of Sonic Colors, Sonic and Tails can be seen taking the space elevator to get to Doctor Eggman Park.
see also
space gun
starting loop
space fountain
Notes
http://galspace.spb.ru/nature.file/lift.html Space elevator and nanotechnology
In space - on the elevator! // KP.RU
Space Elevator Orbits and popular science magazine "Russian Space" No. 11, 2008
Carbon nanotubes are two orders of magnitude stronger than steel
MEMBRANE | World news | Nanotubes won't survive a space elevator
New graphene paper is stronger than steel
Lemeshko Andrey Viktorovich. Space lift Lemeshko A.V./ Space lift Lemeshko A.V.
en:Satellite television#Technology
Elevator to the sky set records with an eye to the future
A laser has been developed that can power space elevators
LaserMotive to Demonstrate Laser-Powered Helicopter at the AUVSI's Unmanned Systems North America 2010
WITH light hand physicists and science fiction writers, the idea of a space elevator is firmly planted in the minds of astronautics enthusiasts. Few imagined futures are complete without gigantic infrastructure carrying people and cargo straight into orbit. But will a space elevator be built in the real future? Sadly, but there are big doubts about this.
The modern fashion for the development of micro-, nano- and even femtosatellites weighing less than 100 g is associated not only with the miniaturization of electronics, but also with purely economic reasons. Despite the fact that over the decades of development of space technology, the cost of launching cargoes into near-Earth orbit has fallen by an order of magnitude, a significant share of the cost of space missions is still their delivery to the place. This factor seriously slows down the entire cosmonautics, turning it into the lot of only financially secure organizations and blocking the way for a lot of developers and researchers.
Each rocket and each upper stage is a piece product, requiring months or even years of production - and, moreover, a one-time one: after working for a maximum of ten minutes, they die. It is not for nothing that both the American corporation SpaceX and Russian engineers are working hard to develop options for creating at least reusable first stages - the most powerful and expensive components of launch systems. Such a project was developed in GKNPTs im. Khrunichev's "Baikal-Angara" or the SpaceX Grasshopper project is the first stage landing on "legs" for rockets of the Falcon family.
But all these are only half measures: it is required to reduce the cost of space flights by an order of magnitude, and for this it is more appropriate not to modify the old ones, but to work them out. And the first in their line will, of course, be a space elevator, an idea as promising as it is simple.
Hassle-free space elevator concept
Take an ordinary rope and quickly unwind around you - that's the whole concept of a space elevator in a nutshell. Tied to the Earth, a sufficiently long and strong cable, going into near-Earth orbit, will hang vertically, as if by itself, due to centrifugal force. It remains to mount a lifting platform on it - and you can go into space. Unfortunately, in practice, with the implementation of a simple idea, everything is far from being so simple.
Perhaps the most famous and actively developing space elevator project is trying to implement the American startup LiftPort. Already from its name it is clear that the main goal of the developers is not just a “space”, but a “lunar” elevator, which allows to establish uninterrupted communication along the Earth-Moon line.
According to the calculations of the company's specialists, the main infrastructure of the space elevator should be tied to a floating offshore platform, which will provide the system with the necessary dynamism. The cable rising from it will reach a height of about 100 thousand km. You can get by with a shorter cable, with a height of "only" about 35.5 thousand km - the main thing is that it reaches the geostationary orbit, which will allow it to remain in an upright position.
Even the strongest steel cannot withstand such loads, and so that the space elevator cable does not break under its own weight, it is proposed to make it from carbon nanotubes, which are distinguished by their low weight and amazing strength. However, the production of nanotubes at least a few centimeters long remains an unresolved technological problem. What can we say about kilometers.
And even if the problem is solved, graphene may not help.
Proposed space elevator design
Base. Movable will allow you to evade natural disasters that threaten the support of the cable. Stationary is more convenient in terms of providing the elevator with cheap energy.
Cable. Must support at least its own weight, the weight of associated infrastructure and centrifugal force. According to calculations, its thickness should increase rapidly with height, reaching the station.
Counterweight. It could be a massive "end station" or an asteroid tied to a tether. But if the cable goes beyond the geostationary orbit, it will be held under its own weight, and from the end of it it will be possible to release distant space probes into flight.
Problem One - Space Elevator Material
Indeed, carbon nanotubes are today perhaps the most mechanically strong material known to mankind. The strength of countless sp2 bonds between carbon atoms in a one-dimensional, rolled-up crystal lattice is incredibly high. But this is not enough: according to the famous expert and futurist Howard Keith Henson (Howard Keith Henson), even in the most optimistic calculations, the strength of such a cable will be only about two-thirds of the required value.
Henson believes that the difficulty with nanotubes lies not so much in technology as in their very structure. It is necessary to learn how to produce not only long nanotubes, but also ideal ones, with a “purity” no worse than that of precious stones. Otherwise, the same sp2 bonds that bind six carbon atoms in graphene will lose their stable configuration and, in the places of defects, will cover 5 or 7 atoms, sharply reducing strength.
The engineer compares this to the holds on women's stockings: a single violation can lead to the "spread" of the entire structure. And if even the production of large, on the order of centimeter-sized, defect-free crystals still remains an unsolved problem, will it be solved in relation to nanotubes many kilometers long? If it does, it won't be for the foreseeable future, says Keith Henson. The cable of a space elevator must withstand up to 100 MN/(kg/m), and even if carbon nanotubes reach this level, they must not contain a single defect, otherwise the cable will unravel before we even try to go to space on it.
According to some estimates, the space elevator cable should have a strength of more than 130 GPa. For comparison, Kevlar reaches a level of 4 GPa, the strongest types of steel - only 5 GPa. Theoretically, carbon nanotubes can have a strength of the desired value (up to 300 GPa), but in practice only about 50 GPa is achieved (and 99 GPa in one of the experiments). At the same time, the technologies for manufacturing long nanotubes - and even more so for weaving cables from them - remain in their infancy.
Even one of the biggest enthusiasts of space elevators, physicist David Appell (David Appell), who leads several related projects, once admitted: ? Unfortunately, no one can answer this question yet.
Problem two: fluctuations
Suppose we made a breakthrough and created carbon nanotubes of the required length, achieved a defect-free structure, wove an elevator cable from them, and even raised it to the desired height. What's next? And then - routine life with its million dangerous details. After all, such a structure will inevitably experience a wide variety of influences, many of which threaten to destroy the entire complex structure.
Such calculations were made by the Czech astrophysicist Lubos Perek, showing that a combination of several factors - the play of gravitational forces from the Earth and the Moon, the pressure of solar wind particles, etc. - can have an unpredictable effect on the space elevator cable. Perec found that the interplay of these forces could cause his entire vast structure to sway, vibrate, and twist.
The solution may be to place special motors on critical sections of the cable, which, controlled by an intelligent computer system, will compensate for unpredictable environmental effects. But the “purity of the concept” will already be violated, and with it, many advantages of the space elevator will be called into question. Engines need fuel, regular maintenance, repair and even replacement. They will not only make it difficult to move along the cable, but, apparently, will significantly increase the cost of operating the elevator.
But this is still flowers, because, like any stretched string, the space elevator cable will have its own resonant frequency of internal oscillations. Remember the story that all school physics teachers traditionally tell in a lesson about resonance - how a detachment of soldiers, marching along a bridge, accidentally "hit" its resonant frequency - and destroyed the entire bridge? Approximately the same threatens the space elevator.
In order to foresee this threat, it will be necessary to install knots damping dangerous vibrations on a number of sections of the cable.
And this is again an additional complication of the design, new engineering problems and financial costs ... And if everything were limited to this: in fact, the cable will have much more problems.
To reduce the size of the cable, get rid of its excessive thickening and the dangers of the lower layers of the atmosphere, the base of the elevator can be placed on a high-altitude - up to 100 km - tower. In August 2015, the Canadian company Thoth Technology Inc. even patented a similar project
The ThothX Tower, which the Canadians plan to build, should reach a moderate height - "only" 20 km - and will be able to be powered by wind energy arising from the pressure difference at its base and at the top. According to the calculations of engineers, it can also be used as a launch pad for rockets, which can significantly reduce the cost of traditional space launches. There is only one problem with the tower: the project is technologically unfeasible.
Problem Three: Space Elevator Passengers
Particular difficulties can be created by ... the very movement of a loaded space elevator along the cable. Like everything that moves on the rotating Earth at an angle to its axis of rotation, the load will be affected by the Coriolis force. Rising up, the elevator will deviate in the opposite direction to the rotation of the Earth. This impact has also been calculated by physicists.
According to Canadian scientist Arun Misra, who did this work, this influence will cause the elevator to swing like an inverted pendulum. As a result, the “destination” in orbit where people and cargo will arrive may not be exactly where they were going. This is completely unacceptable for launching vehicles into orbit.
Moreover, vibrations propagating along the cable will lead to uneven movement of the “cabin”, which will slow down in some areas, and accelerate in others, “driven” by the waves. Of course, a number of mechanisms can be proposed to compensate for this effect as well. For example, an extremely slow and careful, controlled ascent, which Arun Misra estimates will take several weeks, can help.
Another option is the extremely precise coordination of the movement of many cabins at the same time, which will mutually compensate for each other's effects on the cable. But this again complicates and increases the cost of the entire infrastructure. It seems that the idea of a space elevator no longer looks so attractive? But wait: we're not done yet.
Problem Four: Space Debris
Not so long ago, the orbit of the International Space Station was adjusted for the umpteenth time to avoid a collision with another piece of space debris. With the cyclopean design of the elevator, this will not work: it will be almost impossible to move it. And meanwhile, passing through low earth orbit and reaching geostationary orbit, it will be exposed to dozens of working satellites, and thousands of fragments of already out of order devices, rocket stages and upper stages. Let's not forget about the danger of meeting with meteorites!
It is unlikely that this will be avoided at all, and any space elevator must initially be designed for regular and dangerous collisions. How to achieve this is also still unclear: fragments of space debris may not be that big, but they move at tremendous speeds, at which, in the words of the poet, "a grain of sand acquires the strength of a bullet." Howard Keith Henson, already familiar to us, calculated that the energy of such blows easily reaches a level that threatens to simply evaporate several meters of cable.
It is not so difficult to equip all spacecraft whose orbits threaten to cross the elevator cable with active avoidance systems. But what about the already working satellites? What about space debris? According to available estimates, its number in orbit is several thousand tons. And before we can begin deploying the megatether for our superlift, space needs to be cleaned up.
As one of the protection options, it is proposed to install powerful laser systems in critical areas of the elevator, operating in the manner of "air defense" and destroying debris that threatens to collide. But this is correct! - means a new complication and rise in the cost of our wonderful project.
Problems five and six: space elevator wear and radiation
If the four key problems of the space elevator did not seem enough to you, we will mention a couple more. They are not so significant, but also require attention - and are obligatory for a decision.
Wear and corrosion. Under the influence of harsh factors in the atmosphere and the aggressive space environment, both the elevator cable and its parts will inevitably deteriorate. It is necessary to provide options for the restoration of materials, regular repair of the entire structure and maintenance of it.
Radiation. The path of the space elevator will pass not only in the atmosphere, but also far beyond it. It will not blow away the Earth's radiation belts (in Western literature they are called Van Allen belts) - areas where a huge number of charged and high-energy particles captured by the planet's magnetosphere, mainly protons and electrons, are retained. The inner radiation belt is located at an altitude of about 4 thousand km, the outer - 17 thousand km, and any travel of people through these areas is fraught with very serious danger. Therefore, radiation protection measures must be provided for space elevator passengers.
But that's not all. Even if we install powerful screens in the elevator cabin that block the flow of high-energy particles, we will face a different range of problems, by no means technological ones.
Problem Seven: Society
Suppose that international cooperation and the best minds of mankind will solve all the difficulties voiced and the space elevator will proudly rise above the Earth, trampling on the harsh gravity. The colossal structure, of course, will become one of the key symbols of the progress, success and prosperity of the Western, scientifically oriented civilization. So, it will turn into an attractive object for all its opponents.
The destruction of a space elevator by terrorist attacks could be an event that would dwarf in both scope and impact anything that happened on September 11, 2001 in New York and thereafter. The death of this giant will be a serious blow both financially and in the most literal sense: imagine an uncontrolled fall of a cable tens of thousands of kilometers long and a multi-ton mass with all the elements mounted on it ... It is not surprising that the elevator must be 100% protected from all possible attacks from land and air.
By the way, it was these considerations that became one of the important reasons why it is proposed to build the ground infrastructure of the space elevator on an offshore platform, which is much easier to defend against amateur terrorists. But even here, unpredictable consequences await us - already on the part of environmental activists.
Their concern is understandable: as noted by many defenders of the planet, the large scale of freight traffic along the elevator cable is fraught with the appearance of additional mass tightly tied to the Earth. Elementary calculations show that with a colossal length of the cable, this can even affect the speed of the planet's rotation around its axis, slowing it down. The consequences of such an influence can be truly unpredictable. And even if we slow down the Earth by a few nanoseconds, we can expect the most violent protests of the "greens" - for example, under slogans like "Let's save the angular momentum of the planet!".
No problem: on the moon
It seems that the space elevator problems are innumerable and practically unsolvable. But what if we turn the concept of the project into literally upside down?.. Some time ago, an American engineer and developer of space technology, Jerome Pearson, made such a proposal. “On Earth, such a project seems to make little sense,” he writes, “but the Moon is a completely different matter.”
Of course, under the influence of Earth's gravity, the Moon does not rotate around its axis, remaining only one of its sides turned towards us. But Jerome Pearson even sees a plus in this, proposing to “fix” the cable of the space elevator starting on the surface of the satellite, not due to centrifugal force, but due to the Earth's gravity. It is enough just to weight its far end with the corresponding mass: according to Pearson's calculations, with a weight of about 100 thousand tons, such a design will allow three to four times more cargo to be delivered to the Moon annually.
The idea doesn't seem to make sense. Theoretically, a "lunar elevator" does not even require heavy-duty materials, not to mention remarkable - almost perfect - protection from terrorist attacks. The idea is also supported by Keith Henson, who calculated that to lift 1,000 tons of cargo, the system would require the operation of a medium-sized power plant - only 15 MW - and at the same time it could deliver them up to 190 thousand km, into a transfer orbit to Earth.
If mankind seriously begins the development of lunar resources, perhaps the project will be very useful. In the meantime, a space elevator is hardly possible on Earth for technological reasons, while from the Moon we simply have nothing to carry in such quantities. Looks like the elevator is delayed.
Please enable JavaScript to view theThe Japanese company Obayashi Corporation presented the concept of a vehicle into space.
It will be a space elevator from Earth to orbit. The launch of the elevator is planned for 2050.
And about fifty years ago, people thought that at the beginning of the 21st century, space flights would be available to everyone and several times. Unfortunately, it is not.
This elevator will lead from Earth to the space station, located at an altitude of 36 thousand kilometers.
But the length of the cable will be 96 thousand kilometers. This is necessary in order to create an orbital counterweight.
In the future, it can be used to extend the route of the elevator.
The elevator will be able to move at a speed of 200 kilometers per hour and carry up to 30 people at the same time.
So in order to achieve the ultimate goal of this vehicle it will take about 8 days.
The space station will house laboratories and living quarters.
Sounds nice. But there are doubts about the impracticality of such a design.
1. There is not enough strong material for the cable
The load on the cable can exceed 100,000 kg/m, so the material for its manufacture must have extremely high strength to resist stretching, and at the same time very low density. While there is no such material, even carbon nanotubes, which are now considered the most durable and elastic materials on the planet, are not suitable. Unfortunately, the technology for their production is just beginning to be developed. So far, tiny bits of material have been obtained: the longest nanotube ever created is a couple of centimeters long and a few nanometers wide. Whether it will ever be possible to make a sufficiently long cable out of this is still unknown.
2. Susceptibility to dangerous vibrations
The cable will be susceptible to unpredictable gusts of solar wind - under its influence it will bend, and this will negatively affect the stability of the elevator. Micromotors can be attached to the cable as stabilizers, but this measure will create additional difficulties in terms of Maintenance structures. In addition, this will make it difficult for special cabins, the so-called "alpinists", to move along the cable. The cable will most likely resonate with them.
3. Coriolis force
The cable and "alpinists" are motionless relative to the surface of the Earth. But in relation to the center of the Earth, the object will move at a speed of 1,700 km / h on the surface and 10,000 km / h in orbit. Accordingly, the “alpinists” must be given this speed when starting. The "Alpinist" accelerates in a direction perpendicular to the cable, and because of this, the cable will swing like a pendulum. At the same time, a force arises that tries to tear our cable from the Earth. The force is inversely proportional to the amount of cable deflection and directly proportional to the speed of lifting the load and its mass. Thus, the Coriolis force makes it difficult to quickly lift payloads into geostationary orbit. The Coriolis force can be fought by simply launching two "climbers" at the same time - from the Earth and from orbit, but then the force between the two loads will stretch the cable even more. As an option - a painfully slow rise on a caterpillar track.
4. Satellites and space debris
Over the past 50 years, mankind has launched many objects into space - useful and not very. Or the elevator builders will have to find it all and remove it (which is impossible, given the number of useful satellites or orbiting telescopes), or provide a system that protects the object from collisions. The cable is theoretically motionless, so any body rotating around the Earth will collide with it sooner or later. In addition, the speed of the collision will be almost equal to the speed of rotation of this body, so the cable will suffer a lot of damage. The cable cannot maneuver, and it has a large length, so collisions will be frequent. How to deal with this is not yet clear. Scientists talk about building an orbital space laser to incinerate debris, but this is completely out of the realm of science fiction.
5. Social and environmental risks
The space elevator could very well be the target of a terrorist attack. A successful demolition operation will cause enormous damage and may even bury the entire project, so at the same time as the elevator, you will have to build a round-the-clock defense around it. Ecologists also believe that the cable, paradoxically, can shift the earth's axis. The tether will be rigidly fixed in orbit, and any shift at the top will be reflected on the Earth. By the way, can you imagine what will happen if it suddenly breaks off? Thus, it is very difficult to implement such a project on Earth. And now the good news: it will work on the moon. The force of gravity on the satellite is much less, and the atmosphere is virtually absent. An anchor can be created in the Earth's gravity field, and the cable from the Moon will pass through the Lagrange point - thus, we get a communication channel between the planet and its natural satellite. Such a cable, under favorable conditions, will be able to transport about 1,000 tons of cargo per day into the earth's orbit. The material, of course, will need to be heavy-duty, but nothing fundamentally new will have to be invented. True, the length of the "lunar" elevator will have to be about 190,000 km due to an effect called the Hohmann trajectory.
