Megascale engineering
Encyclopedia
Megascale engineering is a form of exploratory engineering
concerned with the construction of structures on an enormous scale. Typically these structures are at least 1,000 kilometers in length—in other words, at least 1 megameter, hence the name. Such large-scale structures are termed megastructure
s.
In addition to large-scale structures, megascale engineering is also defined as including the transformation of entire planets into a human
-habitable environment, a process known as terraforming
or planetary engineering
. This might also include transformation of the surface conditions, changes in the planetary orbit, and structures in orbit intended to modify the energy balance.
Astroengineering
is the extension of megascale engineering to megastructures on a stellar
scale or larger, such as Dyson sphere
s, Ringworld
s, and Alderson disk
s.
Megascale engineering often plays a major part in the plot of science fiction
movies and books. The micro-gravity environment of outer space
provides several potential benefits for the engineering of these structures. These including minimizing the loads on the structure, the availability of large quantities of raw materials in the form of asteroid
s, and an ample supply of energy from the Sun
. The capabilities to employ these advantages are not yet available, however, so they provide material for science fiction themes.
Quite a few megastructures have been designed on paper as exploratory engineering
. However, the list of existing and planned megastructures is complicated by the fact that there are no universally agreed-upon criteria for a structure to be called a megastructure. By the most strict definitions, no megastructures currently exist (with the space elevator
being the only such project under serious consideration). By more lenient definitions, the Great Wall of China
(6.7 Mm
) counts as a megastructure.
A more complete list of conceptual and existing megastructures, along with a discussion of megastructure criteria, is found under megastructure
.
Of all the proposed megastructures, only the orbital elevator
, the Lofstrom
launch loop
, and Martian or lunar space elevator
concepts could be built using conventional engineering
techniques, and are within the grasp of current material science. Carbon nanotubes may have the requisite tensile strength
for the more technologically challenging Earth-based space elevator
, but creation of nanotubes of the required length is a laboratory exercise, and adequate cable-scale technology has not yet been shown at all.
The assembly of structures more massive than a space elevator would likely involve a combination of new engineering techniques, new materials, and new technologies
. Such massive construction projects might require the use of self-replicating
machines to provide a suitably large "construction crew". The use of nanotechnology
might provide both the self-replicating assemblers, and the specialized materials needed for such a project. Nanotechnology
is, however, another area of speculative exploratory engineering
at this time.
Exploratory engineering
Exploratory engineering is a term coined by K. Eric Drexler to describe the process of designing and analyzing detailed hypothetical models of systems that are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible...
concerned with the construction of structures on an enormous scale. Typically these structures are at least 1,000 kilometers in length—in other words, at least 1 megameter, hence the name. Such large-scale structures are termed megastructure
Megastructure
A megastructure is a very large manmade object, though the limits of precisely how large this is vary considerably. Some apply the term to any especially large or tall building....
s.
In addition to large-scale structures, megascale engineering is also defined as including the transformation of entire planets into a human
Human
Humans are the only living species in the Homo genus...
-habitable environment, a process known as terraforming
Terraforming
Terraforming of a planet, moon, or other body is the hypothetical process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to those of Earth, in order to make it habitable by terrestrial organisms.The term is sometimes used more generally as a...
or planetary engineering
Planetary engineering
Planetary engineering is the application of technology for the purpose of influencing the global properties of a planet. The goal of this theoretical task is usually to make other worlds habitable for life....
. This might also include transformation of the surface conditions, changes in the planetary orbit, and structures in orbit intended to modify the energy balance.
Astroengineering
Astroengineering
Astroengineering is the construction of megastructures in space by technologically advanced beings. It is a form of megascale engineering. Typically proposed feats of astroengineering are on the scale to remake an entire stellar system....
is the extension of megascale engineering to megastructures on a stellar
Stellar
Stellar is an adjective referring to one or more stars. It may also refer to:* Hyundai Stellar, a car built by Hyundai Motor Company* "Stellar*", a New Zealand-based rock band.* "Stellar" , a song by Incubus...
scale or larger, such as Dyson sphere
Dyson sphere
A Dyson sphere is a hypothetical megastructure originally described by Freeman Dyson. Such a "sphere" would be a system of orbiting solar power satellites meant to completely encompass a star and capture most or all of its energy output...
s, Ringworld
Ringworld
Ringworld is a Hugo, Nebula, and Locus award-winning 1970 science fiction novel by Larry Niven, set in his Known Space universe and considered a classic of science fiction literature. It is followed by three sequels, and preceded by four prequels, and ties into numerous other books set in Known Space...
s, and Alderson disk
Alderson disk
An Alderson disk is an artificial astronomical megastructure, like Niven's Ringworld, or a Dyson sphere. The disk is a giant platter with a thickness of several thousand miles. The sun rests in the hole at the center of the disk. The outer radius of an Alderson disk would be roughly equivalent...
s.
Megascale engineering often plays a major part in the plot of science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
movies and books. The micro-gravity environment of outer space
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
provides several potential benefits for the engineering of these structures. These including minimizing the loads on the structure, the availability of large quantities of raw materials in the form of asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s, and an ample supply of energy from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. The capabilities to employ these advantages are not yet available, however, so they provide material for science fiction themes.
Quite a few megastructures have been designed on paper as exploratory engineering
Exploratory engineering
Exploratory engineering is a term coined by K. Eric Drexler to describe the process of designing and analyzing detailed hypothetical models of systems that are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible...
. However, the list of existing and planned megastructures is complicated by the fact that there are no universally agreed-upon criteria for a structure to be called a megastructure. By the most strict definitions, no megastructures currently exist (with the space elevator
Space elevator
A space elevator, also known as a geostationary orbital tether or a beanstalk, is a proposed non-rocket spacelaunch structure...
being the only such project under serious consideration). By more lenient definitions, the Great Wall of China
Great Wall of China
The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...
(6.7 Mm
Megametre
A megametre is a unit of length in the metric system, equal to one million metres, the SI base unit of length, hence to 1,000 km or approximately 621.37 miles....
) counts as a megastructure.
A more complete list of conceptual and existing megastructures, along with a discussion of megastructure criteria, is found under megastructure
Megastructure
A megastructure is a very large manmade object, though the limits of precisely how large this is vary considerably. Some apply the term to any especially large or tall building....
.
Of all the proposed megastructures, only the orbital elevator
Orbital ring
An Orbital Ring is a concept for a space elevator that consists of a ring in low earth orbit that rotates at above orbital speed, that has fixed tethers hanging down to the ground.The structure is intended to be used for space launch....
, the Lofstrom
Keith Lofstrom
Keith Lofstrom is an electrical engineer. He has a BSEE and MSEE from University of California, Berkeley.He is more widely known in the space advocacy community for a ground-based space launcher design, the Launch Loop,...
launch loop
Launch loop
A launch loop or Lofstrom loop is a proposed system for launching objects into space orbit using a moving cable-like system attached to the earth at two ends and suspended above the atmosphere in the middle...
, and Martian or lunar space elevator
Lunar space elevator
A lunar space elevator is a proposed cable running from the surface of the Moon into space.It is similar in concept to the better known Earth space elevator idea...
concepts could be built using conventional engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
techniques, and are within the grasp of current material science. Carbon nanotubes may have the requisite tensile strength
Tensile strength
Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...
for the more technologically challenging Earth-based space elevator
Space elevator
A space elevator, also known as a geostationary orbital tether or a beanstalk, is a proposed non-rocket spacelaunch structure...
, but creation of nanotubes of the required length is a laboratory exercise, and adequate cable-scale technology has not yet been shown at all.
The assembly of structures more massive than a space elevator would likely involve a combination of new engineering techniques, new materials, and new technologies
Technology
Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
. Such massive construction projects might require the use of self-replicating
Self-replication
Self-replication is any behavior of a dynamical system that yields construction of an identical copy of that dynamical system. Biological cells, given suitable environments, reproduce by cell division. During cell division, DNA is replicated and can be transmitted to offspring during reproduction...
machines to provide a suitably large "construction crew". The use of nanotechnology
Nanotechnology
Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...
might provide both the self-replicating assemblers, and the specialized materials needed for such a project. Nanotechnology
Nanotechnology
Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...
is, however, another area of speculative exploratory engineering
Exploratory engineering
Exploratory engineering is a term coined by K. Eric Drexler to describe the process of designing and analyzing detailed hypothetical models of systems that are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible...
at this time.
See also
- Kardashev scaleKardashev scaleThe Kardashev scale is a method of measuring an advanced civilization's level of technological advancement. The scale is only theoretical and in terms of an actual civilization highly speculative; however, it puts energy consumption of an entire civilization in a cosmic perspective. It was first...
- Space manufacturingSpace manufacturingSpace manufacturing is the production of manufactured goods in an environment outside a planetary atmosphere. Typically this includes conditions of microgravity and hard vacuum.Manufacturing in space has several potential advantages over Earth-based industry....
- Stellar engineeringStellar engineeringStellar engineering is a type of engineering concerned with creating or modifying stars through artificial means....
- macro-engineeringMacro-engineeringIn engineering, macro-engineering is the implementation of extremely large-scale design projects...