Island Three
Encyclopedia
Space habitat
A space habitat is a space station intended as a permanent settlement rather than as a simple waystation or other specialized facility...
design proposed by American physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
Gerard K. O'Neill in his 1976 book The High Frontier: Human Colonies in Space
The High Frontier: Human Colonies in Space
The High Frontier: Human Colonies in Space is a 1976 book by Gerard K. O'Neill, a road map for what the United States might do in outer space after the Apollo program, the drive to place a man on the Moon. It envisions large manned habitats in the Earth-Moon system, especially near stable...
.
In the book, O'Neill proposed the colonization of space for the 21st century, using materials extracted from the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
.
An O'Neill cylinder would consist of two counter-rotating cylinders, each 5 miles (8 km) in diameter and 20 miles (32.2 km) long, connected at each end by a rod via a bearing
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
system. They would rotate so as to provide artificial gravity
Artificial gravity
Artificial gravity is the varying of apparent gravity via artificial means, particularly in space, but also on the Earth...
via centrifugal force
Centrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...
on their inner surfaces.
Background
While teaching undergraduate physicsPhysics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
, O'Neill set his students the task of designing large structures in space, with the intent to show that living in space could be desirable. Several of the architectures were able to provide areas large enough to be suitable for human habitation. This cooperative result inspired the idea of the cylinder, and was first published by O'Neill in a September 1974 article of Physics Today
Physics Today
Physics Today, created in 1948, is the membership journal of the American Institute of Physics. It is provided to 130,000 members of twelve physics societies, including the American Physical Society...
.
Island One
Island One is a rotating sphere measuring one mile in circumference (1,681 feet or 512.27 meters in diameter), with people living on the equatorial region (see Bernal sphereBernal sphere
A Bernal sphere is a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by John Desmond Bernal....
). A later NASA/Ames study at Stanford University developed an alternate version of Island One: the Stanford torus
Stanford torus
The Stanford torus is a proposed design for a space habitat capable of housing 10,000 to 140,000 permanent residents.The Stanford Torus was proposed during the 1975 NASA Summer Study, conducted at Stanford University, with the purpose of speculating on designs for future space colonies...
, a toroidal shape 1,600 meters (just under a mile) in diameter.
Island Three
Island Three consists of two counter-rotating cylinderCylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
s, each five miles (8 km) in diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, and capable of scaling up to twenty miles (32 km) long. Each cylinder has six equal-area stripes that run the length of the cylinder; three are transparent windows, three are habitable "land" surfaces. Furthermore, an outer agricultural ring, 10 miles (16 km) in radius, rotates at a different speed to support farming. The habitat's industrial manufacturing block is located in the middle, to allow for minimized gravity for some manufacturing processes.
To save the immense cost of rocketing the materials from Earth, these habitats would be built with materials launched into space from the Moon with a magnetic mass driver
Mass driver
A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets. Sequential...
.
Artificial gravity
The cylinders rotate to provide artificial gravity on their inner surface. Due to their very large radii, the habitats would have to rotate only about forty times an hour to simulate a standard Earth gravityStandard gravity
Standard gravity, or standard acceleration due to free fall, usually denoted by g0 or gn, is the nominal acceleration of an object in a vacuum near the surface of the Earth. It is defined as precisely , or about...
. Research on human factors in rotating reference frames
indicate that almost no-one (at such low rotation speeds) would experience motion sickness
Motion sickness
Motion sickness or kinetosis, also known as travel sickness, is a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement...
due to coriolis forces
Coriolis effect
In physics, the Coriolis effect is a deflection of moving objects when they are viewed in a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right...
acting on the inner ear. People would be able to detect spinward and antispinward directions by turning their heads, and any dropped items would appear to be deflected by a few centimetres.
The central axis of the habitat would be a zero-gravity region, and it was envisaged that recreational facilities could be located there.
Atmosphere and radiation
The habitat was planned to have oxygen at partial pressures roughly similar to terrestrial air, 20% of the Earth's sea-level air pressure. Nitrogen would also be included to add a further 30% of the Earth's pressure. This half-pressure atmosphere would save gas and reduce the needed strength and thickness of the habitat walls.At this scale, the air within the cylinder and the shell of the cylinder provide adequate shielding against cosmic ray
Health threat from cosmic rays
The health threat from cosmic rays is the danger posed by galactic cosmic rays and solar energetic particles to astronauts on interplanetary missions.Galactic cosmic rays consist of high energy protons and other nuclei with extrasolar origin...
s.
Sunlight
Large mirrors are hinged at the back of each stripe of window. The unhinged edge of the windows points toward the Sun. The purpose of the mirrors is to reflect sunlightSunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
into the cylinders through the windows. Night is simulated by opening the mirrors, letting the window view empty space; this also permits heat to radiate to space. During the day, the reflected Sun appears to move as the mirrors move, creating a natural progression of Sun angles. Although not visible to the naked eye, the Sun's image might be observed to rotate due to the cylinder's rotation. The light reflected from the mirrors is polarized, which might confuse bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
s.
To permit light to enter the habitat, large windows run the length of the cylinder. These would not be single panes, but would be made up of many small sections, to prevent catastrophic damage, and so the aluminum or steel window frames can take most of the stresses of the air pressure of the habitat.
Occasionally a meteorite might break one of these panes. This would cause some loss of the atmosphere, but calculations showed that this would not be an emergency, due to the very large volume of the habitat.
Attitude control
First, the pair of habitats can be rolled by operating the cylinders as momentum wheel
Momentum wheel
A reaction wheel is a type of flywheel used primarily by spacecraft for attitude control without using fuel for rockets or other reaction devices....
s. If one habitat's rotation is slightly off, the two cylinders will rotate about each other. Once the plane formed by the two axes of rotation is perpendicular in the roll axis to the orbit, then the pair of cylinders can be yaw
Yaw
The word yaw can refer to:* Yaw angle, one of the Tait-Bryan angles, describing the heading of a vehicle or machine, and some other related elements:**Yaw system, component responsible for the orientation of a wind turbine towards the wind....
ed to aim at the sun by exerting a force between the two sunward bearings. Pushing the cylinders away from each other will cause both cylinders to gyroscopically precess
Precession
Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...
, and the system will yaw in one direction, while pushing them towards each other will cause yaw in the other direction. The counter-rotating habitats have no net gyroscopic
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
effect, and so this slight precession can continue for the habitat's orbit, keeping it aimed at the sun.
Criticism of the design
O'Neil's designs for the colonies are inefficient in their construction, in terms of materials used per square meter of living area. For example, to hold air at 40% of Earth's surface pressure with a standard 5-fold safety margin, the smallest design, the 1.5-km-diameter Island One, would require a steel shell with 2 metric tons of steel per square meter of shell. In contrast, a habitat made of linked 10-meter balls would requires only 24 kilograms of steel per square meter. The habitable area is distributed in different ways in such different designs, but the difference in costs remains huge.See also
- Babylon 5 (space station)Babylon 5 (space station)Babylon 5 is a fictional space station and the primary setting in the television series Babylon 5. Its design is a variation of an O'Neill cylinder....
- Bernal sphereBernal sphereA Bernal sphere is a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by John Desmond Bernal....
- Bishop Ring (habitat)Bishop Ring (habitat)A Bishop Ring is a type of hypothetical rotating space habitat originally proposed in 1997 by Forrest Bishop. As with other space habitat designs, the Bishop Ring would spin to produce artificial gravity by way of centrifugal force. The design differs from the classical designs produced in the...
- Centrifuge Accommodations ModuleCentrifuge Accommodations ModuleThe Centrifuge Accommodations Module is a cancelled element of the International Space Station. Although the module was planned to contain more than the a centrifuge, the centrifuge still was considered the most important capability of the module...
- Deep Space Nine (space station)Deep Space Nine (space station)Deep Space Nine is a fictitious space station, and is the eponymous primary setting of the science fiction television series Star Trek: Deep Space Nine. It serves as a base for the exploration of the Gamma Quadrant via the Bajoran wormhole, and is a hub of trade and travel for the sector's denizens...
- Dyson sphereDyson sphereA 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...
- McKendree cylinderMcKendree cylinderA McKendree cylinder is a type of hypothetical rotating space habitat originally proposed at NASA's Turning Goals into Reality conference in 2000 by NASA engineer Tom McKendree. As with other space habitat designs, the cylinder would spin to produce artificial gravity by way of centrifugal force....
- Globus CassusGlobus CassusGlobus Cassus is an art project and book by Swiss architect and artist Christian Waldvogel presenting a conceptual transformation of Planet Earth into a much bigger, hollow, artificial world with an ecosphere on its inner surface...
- Space stations and habitats in popular culture
- Stanford torusStanford torusThe Stanford torus is a proposed design for a space habitat capable of housing 10,000 to 140,000 permanent residents.The Stanford Torus was proposed during the 1975 NASA Summer Study, conducted at Stanford University, with the purpose of speculating on designs for future space colonies...