Generation ship
Encyclopedia
A generation ship is a hypothetical type of interstellar ark
starship
that travels across great distances between stars
at a speed much slower than the speed of light
. Since such a ship might take thousands of years to reach even nearby stars, the original occupants of a generation ship would grow old and die, leaving their descendants to continue travelling.
, providing energy, food, air, and water
for everyone on board. It must also have extraordinarily reliable systems that could be maintained by the ship's inhabitants over long periods of time. Large, self-sustaining space habitat
s would be needed. For gaining experience before sending generation ships to the stars, such a habitat could be effectively isolated from the rest of humanity for a century or more, but remain close enough to Earth
for help. This would test whether thousands of humans can survive on their own before sending them beyond the reach of help. There are also the concerns of immune systems atrophy
ing in the ship's environment. Small artificial closed ecosystem
s, including Biosphere 2
, have been built in an attempt to work out the engineering difficulties in such a system, with mixed results.
Some have compared planet
s with life (in particular Earth
) to generation ships. This idea is usually called "Spaceship Earth
".
Estimates of the minimum viable population
vary. The results of a 2005 study from Rutgers University theorized that the native population of the Americas
are the descendants of only 70 individuals who crossed the land bridge between Asia and North America. However, anthropologist Dr. John Moore estimated in 2002 that a population of 150 to 180 would allow normal reproduction for 60 to 80 generations, equivalent to 2000 years. Careful genetic screening and use of a sperm bank
from Earth would also allow a smaller starting base with negligible inbreeding.
Generation ships are based on the human life span not changing dramatically. Even though people are living longer and longer it would take a lifespan extension beyond anyone's forecasts for any one individual to live throughout the entire trip.
s and the radiation belts. Like other ionizing radiation
, high-energy cosmic rays can damage DNA
, increasing the risk of cancer, cataracts, neurological disorders, and non-cancer mortality risks. The only known practical solution to this problem is surrounding the crewed parts of the ship with a thick enough shielding, say a couple meters of ice.
stories. Perhaps their earliest description is in the 1929 essay "The World, The Flesh, & The Devil" by J. D. Bernal. The first fiction dealing with one is the 1940 story "The Voyage That Lasted 600 Years" by Don Wilcox.
Beginning with the 1941 novels Universe
and Common Sense
by Robert A. Heinlein, a common theme is that inhabitants of a generation ship have forgotten they are on a ship at all, and believe their ship to be the entire universe. French writer Léon Groc actually wrote the first complete novel about this theme in the 1950 book L'Univers Vagabond. In the anglophone world, Brian Aldiss
is attributed with the first complete novel dealing exclusively with the theme in the 1958 book Non-Stop. Edmund Cooper
's Seed of Light (1959) is already criticized because it again deals with the old subject, but counted the author's best novel. Harry Harrison
's novel Captive Universe
(1969) deals with similar themes.
In the Star Trek: The Original Series
episode For the World Is Hollow and I Have Touched the Sky (1968) the Enterprise encounters a computer-lead generation ship, whose inhabitants does not know they are within a ship travelling through space but instead believe to be on a solid world and that the created sky is real. Harlan Ellison
's The Starlost
, a 1973 Canadian TV series, is set aboard the giant spaceship called The ARK. In the Space: 1999
episode Mission of the Darians
(1975) the Alphans encounter the heavy damaged but still populated generation ship Daria, bearing an evil secret
.
Gene Wolfe
's tetralogy The Book of the Long Sun
(1993) deals directly with the challenges facing the inhabitants of the starcrosser Whorl and the continuing challenges after planetfall in The Book of the Short Sun
(1999). The 2008 Pixar
film WALL-E
contains a subplot in which a generation ship containing humans returns to Earth
after many centuries. Toby Litt
's 2009 novel Journey into Space is about people living on a generation ship who return back to Earth after an onboard conflict. This method of slow interstellar travel is hinted at in Arthur C. Clarke
's Rendezvous With Rama
(1972) as the spacecraft Rama is analyzed, and this theme continues in the book's sequels. The Mass Effect
series features a large caravan of jerry-rigged generation ships, referred to as the Migrant Fleet. The 2010 "Doctor Who
" episode, "The Beast Below
", centres around a generation ship known as "Starship UK", which contains the entire future population of the United Kingdom (except for Scotland, which opted for its own ship) fleeing the deadly solar flares on the Earth in the 29th century.
Interstellar ark
An interstellar ark is a conceptual space vehicle that some have speculated could be used for interstellar travel. The concept was first developed by Dr...
starship
Starship
A starship or interstellar spacecraft is a theoretical spacecraft designed for traveling between the stars, as opposed to a vehicle designed for orbital spaceflight or interplanetary travel....
that travels across great distances between stars
Interstellar travel
Interstellar space travel is manned or unmanned travel between stars. The concept of interstellar travel in starships is a staple of science fiction. Interstellar travel is much more difficult than interplanetary travel. Intergalactic travel, or travel between different galaxies, is even more...
at a speed much slower than the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
. Since such a ship might take thousands of years to reach even nearby stars, the original occupants of a generation ship would grow old and die, leaving their descendants to continue travelling.
Biosphere
Such a ship would have to be almost entirely self-sustainingBiosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...
, providing energy, food, air, and water
Life support system
In human spaceflight, a life support system is a group of devices that allow a human being to survive in space.US government space agency NASA,and private spaceflight companies...
for everyone on board. It must also have extraordinarily reliable systems that could be maintained by the ship's inhabitants over long periods of time. Large, self-sustaining space habitat
Space habitat
A space habitat is a space station intended as a permanent settlement rather than as a simple waystation or other specialized facility...
s would be needed. For gaining experience before sending generation ships to the stars, such a habitat could be effectively isolated from the rest of humanity for a century or more, but remain close enough to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
for help. This would test whether thousands of humans can survive on their own before sending them beyond the reach of help. There are also the concerns of immune systems atrophy
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
ing in the ship's environment. Small artificial closed ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s, including Biosphere 2
Biosphere 2
Biosphere 2 is a structure originally built to be an artificial, materially-closed ecological system in Oracle, Arizona by Space Biosphere Ventures, a joint venture whose principal officers were John P. Allen, inventor and Executive Director, and Margret Augustine, CEO...
, have been built in an attempt to work out the engineering difficulties in such a system, with mixed results.
Some have compared planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s with life (in particular Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
) to generation ships. This idea is usually called "Spaceship Earth
Spaceship Earth
Spaceship Earth is a world view term usually expressing concern over the use of limited resources available on Earth and the behavior of everyone on it to act as a harmonious crew working toward the greater good....
".
Biology and society
Generation ships would also have to solve major biological, social and moral problems, and would also need to deal with complex matters of self-worth and purpose for the various crews involved. As an example, a moral quandary might exist regarding how intermediate generations (for example, those destined to be born, reproduce, and die in transit, without actually seeing tangible results of their efforts) might feel about their forced existence on such a ship.Estimates of the minimum viable population
Minimum Viable Population
Minimum viable population is a lower bound on the population of a species, such that it can survive in the wild. This term is used in the fields of biology, ecology, and conservation biology...
vary. The results of a 2005 study from Rutgers University theorized that the native population of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
are the descendants of only 70 individuals who crossed the land bridge between Asia and North America. However, anthropologist Dr. John Moore estimated in 2002 that a population of 150 to 180 would allow normal reproduction for 60 to 80 generations, equivalent to 2000 years. Careful genetic screening and use of a sperm bank
Sperm bank
A sperm bank, semen bank or cryobank is a facility that collects and stores human sperm mainly from sperm donors, primarily for the purpose of achieving pregnancies through third party reproduction, notably by artificial insemination...
from Earth would also allow a smaller starting base with negligible inbreeding.
Generation ships are based on the human life span not changing dramatically. Even though people are living longer and longer it would take a lifespan extension beyond anyone's forecasts for any one individual to live throughout the entire trip.
Cosmic rays
The radiation environment of deep space is very different from that on the Earth's surface or in low earth orbit, due to the much larger flux of high-energy galactic cosmic rays (GCRs), along with radiation from solar proton eventSolar proton event
A Solar proton event occurs when protons emitted by the Sun become accelerated to very high energies either close to the Sun during a solar flare or in interplanetary space by the shocks associated with coronal mass ejections. These high energy protons cause several effects. They can penetrate the...
s and the radiation belts. Like other ionizing radiation
Ionizing radiation
Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
, high-energy cosmic rays can damage DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
, increasing the risk of cancer, cataracts, neurological disorders, and non-cancer mortality risks. The only known practical solution to this problem is surrounding the crewed parts of the ship with a thick enough shielding, say a couple meters of ice.
Technological progress
If ever mankind is so enthusiastic about interstellar travel that a generation ship is sent to a star system 20 light years away in 200 years, it is quite unlikely that those remaining at home will just wait 220 years to hear the news of the success of the mission, and would not build any further starships meanwhile. So, if 50 years after launch they build a better spaceship that can make the same travel in just 50 years, when the first generation ship arrives they might find a 100-years old human colony at their destination.In fiction
Generation ships are often found in science fictionScience 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...
stories. Perhaps their earliest description is in the 1929 essay "The World, The Flesh, & The Devil" by J. D. Bernal. The first fiction dealing with one is the 1940 story "The Voyage That Lasted 600 Years" by Don Wilcox.
Beginning with the 1941 novels Universe
Orphans of the Sky
Orphans of the Sky is a science fiction novel by Robert A. Heinlein, consisting of two parts: "Universe" and its sequel, "Common Sense" . The two novellas were first published together in book form in 1963. "Universe" was also published separately in 1951 as a 10¢ Dell paperback...
and Common Sense
Orphans of the Sky
Orphans of the Sky is a science fiction novel by Robert A. Heinlein, consisting of two parts: "Universe" and its sequel, "Common Sense" . The two novellas were first published together in book form in 1963. "Universe" was also published separately in 1951 as a 10¢ Dell paperback...
by Robert A. Heinlein, a common theme is that inhabitants of a generation ship have forgotten they are on a ship at all, and believe their ship to be the entire universe. French writer Léon Groc actually wrote the first complete novel about this theme in the 1950 book L'Univers Vagabond. In the anglophone world, Brian Aldiss
Brian Aldiss
Brian Wilson Aldiss, OBE is an English author of both general fiction and science fiction. His byline reads either Brian W. Aldiss or simply Brian Aldiss. Greatly influenced by science fiction pioneer H. G. Wells, Aldiss is a vice-president of the international H. G. Wells Society...
is attributed with the first complete novel dealing exclusively with the theme in the 1958 book Non-Stop. Edmund Cooper
Edmund Cooper
Edmund Cooper was an English poet and prolific writer of speculative fiction, romances, technical essays, several detective stories, and a children's book. These were published under his own name and several pen names...
's Seed of Light (1959) is already criticized because it again deals with the old subject, but counted the author's best novel. Harry Harrison
Harry Harrison
Harry Harrison is an American science fiction author best known for his character the Stainless Steel Rat and the novel Make Room! Make Room! , the basis for the film Soylent Green...
's novel Captive Universe
Captive Universe
Captive Universe is a science fiction novel by American author Harry Harrison, which was first published in 1969.-Plot synopsis:Chimal is a young Aztec tribesman living in an isolated valley which was sealed off from the rest of the world in ages past by a massive earthquake...
(1969) deals with similar themes.
In the Star Trek: The Original Series
Star Trek: The Original Series
Star Trek is an American science fiction television series created by Gene Roddenberry, produced by Desilu Productions . Star Trek was telecast on NBC from September 8, 1966, through June 3, 1969...
episode For the World Is Hollow and I Have Touched the Sky (1968) the Enterprise encounters a computer-lead generation ship, whose inhabitants does not know they are within a ship travelling through space but instead believe to be on a solid world and that the created sky is real. Harlan Ellison
Harlan Ellison
Harlan Jay Ellison is an American writer. His principal genre is speculative fiction.His published works include over 1,700 short stories, novellas, screenplays, teleplays, essays, a wide range of criticism covering literature, film, television, and print media...
's The Starlost
The Starlost
The Starlost is a Canadian-produced science fiction television series devised by writer Harlan Ellison and broadcast in 1973 on CTV in Canada and syndicated to local stations in the United States. The show's setting is a huge generational colony spacecraft called The Ark, which has gone off-course...
, a 1973 Canadian TV series, is set aboard the giant spaceship called The ARK. In the Space: 1999
Space: 1999
Space: 1999 is a British science-fiction television series that ran for two seasons and originally aired from 1975 to 1977. In the opening episode, nuclear waste from Earth stored on the Moon's far side explodes in a catastrophic accident on 13 September 1999, knocking the Moon out of orbit and...
episode Mission of the Darians
Mission of the Darians
"Mission of the Darians" is the twenty-second episode of the first series of Space: 1999. The screenplay was written by Johnny Byrne; the director was Ray Austin. The original title was ‘Mission of the Darya’. The final shooting script is dated 7 January 1975...
(1975) the Alphans encounter the heavy damaged but still populated generation ship Daria, bearing an evil secret
Cannibalism
Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...
.
Gene Wolfe
Gene Wolfe
Gene Wolfe is an American science fiction and fantasy writer. He is noted for his dense, allusive prose as well as the strong influence of his Catholic faith, to which he converted after marrying into the religion. He is a prolific short story writer and a novelist, and has won many awards in the...
's tetralogy The Book of the Long Sun
The Book of the Long Sun
The Book of the Long Sun is a tetralogy by Gene Wolfe, comprising Nightside of the Long Sun, Lake of the Long Sun, Caldé of the Long Sun, and Exodus from the Long Sun. The first two volumes are published together as Litany of the Long Sun and the last two as Epiphany of the Long Sun...
(1993) deals directly with the challenges facing the inhabitants of the starcrosser Whorl and the continuing challenges after planetfall in The Book of the Short Sun
The Book of the Short Sun
The Book of the Short Sun is a trilogy by Gene Wolfe, comprising On Blue's Waters , In Green's Jungles , and Return to the Whorl . It is the sequel to Wolfe's tetralogy The Book of the Long Sun, and has connections to The Book of the New Sun...
(1999). The 2008 Pixar
Pixar
Pixar Animation Studios, pronounced , is an American computer animation film studio based in Emeryville, California. The studio has earned 26 Academy Awards, seven Golden Globes, and three Grammy Awards, among many other awards and acknowledgments. Its films have made over $6.3 billion worldwide...
film WALL-E
WALL-E
WALL-E, promoted with an interpunct as WALL•E, is a 2008 American computer-animated science fiction film produced by Pixar Animation Studios and directed by Andrew Stanton. The story follows a robot named WALL-E, who is designed to clean up a waste-covered Earth far in the future...
contains a subplot in which a generation ship containing humans returns to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
after many centuries. Toby Litt
Toby Litt
Toby Litt is an English writer, born in Bedford in 1968. He studied at Bedford Modern School, read English at Worcester College, Oxford and studied Creative Writing at the University of East Anglia where he was taught by Malcolm Bradbury....
's 2009 novel Journey into Space is about people living on a generation ship who return back to Earth after an onboard conflict. This method of slow interstellar travel is hinted at in Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...
's Rendezvous With Rama
Rendezvous with Rama
Rendezvous with Rama is a novel by Arthur C. Clarke first published in 1972. Set in the 22nd century, the story involves a cylindrical alien starship that enters Earth's solar system...
(1972) as the spacecraft Rama is analyzed, and this theme continues in the book's sequels. The Mass Effect
Mass Effect (series)
Mass Effect is an award-winning, bestselling series of science fiction RPG third-person shooter video games developed by the Canadian company BioWare and released for the Xbox 360, Microsoft Windows and, from the second installment, for the PlayStation 3...
series features a large caravan of jerry-rigged generation ships, referred to as the Migrant Fleet. The 2010 "Doctor Who
Doctor Who
Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a time-travelling humanoid alien known as the Doctor who explores the universe in a sentient time machine called the TARDIS that flies through time and space, whose exterior...
" episode, "The Beast Below
The Beast Below
"The Beast Below" is the second episode of the fifth series of the British science fiction television series Doctor Who. It was written by showrunner Steven Moffat and broadcast on BBC One and BBC HD on 10 April 2010....
", centres around a generation ship known as "Starship UK", which contains the entire future population of the United Kingdom (except for Scotland, which opted for its own ship) fleeing the deadly solar flares on the Earth in the 29th century.
See also
- Embryo space colonizationEmbryo space colonizationEmbryo space colonization is a theoretical interstellar space colonization concept that involves sending a robotic mission to a habitable terrestrial planet transporting frozen early-stage human embryos or the technological or biological means to create human embryos. The proposal circumvents the...
- Interstellar ArkInterstellar arkAn interstellar ark is a conceptual space vehicle that some have speculated could be used for interstellar travel. The concept was first developed by Dr...
- O'Neill cylinder
- Sleeper shipSleeper shipA sleeper ship is a hypothetical type of manned spaceship in which most or all of the crew spends the journey in some form of hibernation or suspended animation. There is currently no known technology that allows for long-term suspended animation of humans....