Astronautics is going through hard times now. Science is IT-oriented and firmly tied to the economy, delighting consumers with countless gadgets. However, the theoretical groundwork left behind by the Cold War is enough to conquer more than one solar system. Space megaprojects of the past are not forgotten and are still waiting in the wings. And some almost waited.
In the golden age of astronautics, at the height of the space race in the 1950s and 1970s, the unprecedented technological leap of mankind directly into outer space was accompanied by a corresponding rise in engineering. There were a lot of ideas about how we should in practice explore space, ideas that are beautiful, large-scale and far from always utopian; the grandiose designs of the earlier past were also developed.
Of these, modest units were realized. Astronomical projects either turned out to be unfeasible for the then level of technology development, or too expensive for the budgets of both superpowers combined. However, the flywheel of cosmic romanticism cannot be stopped so easily: the dreamy daughter of science, futurology, raised its head and continued to broadcast to the masses all the new concepts of a wonderful future of man in space. Science fiction authors also helped her in this.
Naked Science decided to talk about some mega-projects that excited the minds of people at the dawn of the space age, and which, perhaps, will nevertheless be embodied in the unpredictable reality of future generations.
Star machines
In 1964, the Soviet astrophysicist Nikolai Kardashev proposed a criterion by which it would be possible to objectively determine the technological level of development of a particular civilization. This is how the Kardashev scale known on both sides of the Atlantic appeared, which is based on the degree of control over the energy resources of space.
According to the scale, extraterrestrial civilizations can be divided into three types. A type I civilization uses all the resources of its planet; representatives of type II civilization are able to direct in the right direction all the energy that a star emits in their planetary system; and a Type III civilization is capable of handling the energy of an entire galaxy.
Our civilization is obviously approaching only the first type. However, if energy expansion is really a locomotive that inevitably propels civilization forward, that is, if this is our objective future, then why not dream about how it is practically possible to collect the energy of, say, a whole star?
This is how the concept of stellar machines was born - mega-constructions of astronomical scales that could catch the radiation from the entire surface of the Sun at once to generate energy for the needs of mankind.
Music of celestial spheres, rings and bubbles
A prominent representative of the stellar machine is the Dyson Sphere - a hypothetical spherical structure the size of a planetary orbit, in the center of which is the Sun. It is a thin shell, the inner side of which absorbs the energy of the star, and the outer side is prepared for settlement. In some way, this is a giant and artificial hollow planet, intended for very fertile civilizations (according to Dyson's calculations, up to 1 quadrillion people).
The idea of the Sphere was popularized by the American theoretical physicist Freeman Dyson (he himself, in turn, partially borrowed it from the novel "The Creator of the Stars" by Olaf Stapledon), for which he gained unprecedented citation in the works of science fiction writers, as well as criticism from the scientific community: Dyson's idea defeated by calculations, according to which the Sphere in reality would be inevitably destroyed by the difference in centrifugal force at its poles and equator.
On this, however, the concept of the Sphere did not die, but was developed in the form of various modifications. Some suggested changing its shape - making the Sphere more elongated towards the poles, as well as adding holes to them to avoid destruction; others suggested that the star should be surrounded by separate autonomous satellites in the form of "Swarm Dyson" or "Dyson Bubble", depending on the relative position of the satellites; still others proposed to completely abandon the spherical shape and confine ourselves to a kind of belts-rings surrounding the star.
Engine of all engines
Another hypothetical type of stellar machines - "Shkadov Engine", named after the Soviet scientist Leonid Shkadov, who developed its concept, can also be attributed to a variety of the Dyson Sphere. The engine allows, no less, to move the entire planetary system in the desired direction at zero energy costs.
Such a seemingly fantastic effect in the style of the notorious perpetual motion machine can be achieved by a rather simple design: it is enough to place a giant mirror next to the Sun, the light pressure on which would be compensated by the gravitational attraction of the star. Thus, the radiation of the Sun's surface will become asymmetric, and the star - and with it the planets gravitationally attached to it, including the Earth - will begin a leisurely movement with acceleration towards the motor mirror, and will continue it until there is thermonuclear reactions will stop, and it will not stop shining.
According to calculations, if the mirror reflects half of the solar energy, a billion years of such acceleration will provide the Sun with a speed of 20 km / s, and a distance from the original point of 34 thousand light years - that is, more than a third of our galaxy.
Is there life in space bagels?
As a star tamer, the Dyson Orb is certainly good. And what about its outer side, intended for the resettlement of people? Here the Sphere intersects with another major direction of astroengineering thought, namely, "bagel cities" - projects of artificial space settlements in the form of giant tori, or, more simply, bagels.
Tsiolkovsky was the first to suggest arranging space colonies in the form of toroidal hollow structures that provide internal gravity with their own rotation. During the XX century, scientists, writers and futurologists have proposed many options for such structures, one of the most famous is the "Stanford Torus" (pictured). However, the main elements of the design remained unchanged: the torus, rotation around its axis and people living on the inner side of the torus.
American writer Larry Niven wrote a series of science fiction books "The Ring World", where he combined the idea of a torus city with the Dyson Sphere; in the Niven universe, the "donut" is built around the sun, and its side facing the luminary uses solar energy to support life inside the space colony. For his theoretical developments, Niven received the approval of not only the world public, but also the attention of the scientific community and Freeman Dyson himself.
The concept has been heavily popularized not only in literature. Settlements in the form of tori appeared in the movies ("A Space Odyssey 2001", from the last films - "Elysium"), and then in video games (for example, in the Mass Effect trilogy).
Bagel Cities, of course, are not a project of an ideal space settlement: critics attribute the fatal vulnerability of inhabited tori to threats such as asteroids and solar radiation.
Doors close, next stop is geostationary orbit
The most down-to-earth astro-engineering structure in every sense is the space elevator. The bottom line is simple: the delivery of payloads from the Earth's surface to the orbital station through a lift, or a cable that connects the station with the planet. From the outside, it will look like a thin tower, however, 36 thousand km above sea level.
As in the case of the city-tori, Tsiolkovsky was the first to suggest this idea at the end of the 19th century, but it was widely popularized only in science fiction, in particular, by Arthur Clarke in the final book of his Space Odyssey.
The space elevator is one of the options for the missile-free delivery of goods into space, and not as fantastic as it seems. There is already a material - carbon nanotubes - that theoretically has more than enough strength to build the first space elevator out of it.
Given the current prices for cargo delivery by means of rockets, this technology can significantly ease the financial burden of space powers and stimulate the development of astronautics. For example, it is easy to imagine how much cheaper projects of orbital stations or space colonies will become if their modules can be launched into space on an elevator, and not one per rocket.
Are they already there?
If you think about the Kardashev scale again, then the obvious thought comes to mind: if advanced civilizations have to curb the energy of their stars or surround them with giant orbital cities, then why not explore space in search of traces of such structures? What if someone else has already built them?
Indeed, the search for manifestations of astroengineering activity in outer space is one of the main directions in the search for extraterrestrial civilizations. When Freeman Dyson first described the Sphere already known to us, he was not too lazy to mention that such a megastructure should emit in a specific infrared range, and if radio telescopes are tuned in a certain way, it can be found.
Members of the US-based project for the search for extraterrestrial intelligence SETI took Dyson's recommendations seriously and regularly study the data obtained from radio telescopes. One of the largest such studies was carried out in 2004 by Fermilab. Scientists analyzed panoramic images of the entire sky taken by the infrared space telescope IRAS and found 17 candidates for the Sphere. The authors of the analysis, however, insist that the candidates turned out to be rather “weak”. A similar 2012 study also failed to produce significant results.
Russia is also interested in the search for astroengineering structures. By 2016, it is planned to develop, and by 2018 - to launch into space the Russian space complex for astrophysical research Spektr-M (Millimetron), which, among other things, will be able to take pictures in the infrared range. Among the proposed directions for future research is officially listed as "the search for the presence of extraterrestrial astroengineering activities in the Galaxy and the Universe."
So far, we can say that the astro-engineering of extraterrestrial civilizations still remains indistinguishable for modern science and technology. Does this mean that we are still alone in the universe? Definitely impossible to answer.
“Suppose that some astro engineer“connected”the text of“Hamlet”to a powerful star through the appropriate encoders. Then this engineer, as well as all sentient beings in space, died. The encoder "reads" "Hamlet", that is, turns its text - letter by letter - into impulses that cause strictly defined changes in the star. The star, throwing out prominences, contracting and expanding, transmits "Hamlet" with its fiery pulsations … It can be assumed that the radiation sent by the star during the "transmission" of the scene of the murder of Polonius causes explosions of neighboring stars. Let planets appear around these stars as a result of explosions, and let the rudiments of life appear on these planets by the time of Hamlet's death: the last scenes of the tragedy transmitted by the star in the form of very hard radiation increase the frequency of mutations in the hereditary plasma of these living beings, from which primates are formed over time. " - Stanislav Lem wrote in Summa Technologies.
The prospects for what we might find in our quest are endlessly beautiful. Is not it?