Editing Generation ship

{{Short description|Starship inhabited for multiple generations}}
[[File:Stanford Torus-based generation ship.png|thumb|[[Stanford torus|Stanford Torus]]-based generation ship, proposed by [[Project Hyperion (interstellar)|Project Hyperion]]<ref name="hein-pak-putz-revisited">{{cite journal |last1=Hein |first1=Andreas M. |last2=Pak |first2=Mikhail |last3=Pütz |first3=Daniel |last4=Bühler |first4=Christian |last5=Reiss |first5=Philipp |title=World ships—architectures & feasibility revisited |journal=Journal of the British Interplanetary Society |date=2012 |volume=65 |issue=4 |page=119|url=https://www.researchgate.net/publication/236177990 }}</ref>]]

A '''generation ship''', '''generation starship''' or '''world ship''',<ref name="hein-pak-putz-revisited" /> is a hypothetical type of [[interstellar ark]] [[starship]] that travels at sub-[[speed of light|light speed]]. Since such a ship might require hundreds to thousands of years to reach nearby stars, the original occupants of a generation ship would grow old and die, leaving their descendants to continue traveling.

== Origins ==
Rocket pioneer [[Robert H. Goddard]] was the first to write about long-duration interstellar journeys in his "The Ultimate Migration" (1918).<ref name="CAROTI">{{cite book|author=Simone Caroti|title=The Generation Starship in Science Fiction: A Critical History, 1934-2001|publisher=McFarland|year=2011|isbn=978-0-7864-6067-0|page=275}}</ref> In this he described the death of the Sun and the necessity of an "interstellar ark". The crew would travel for centuries in [[suspended animation in fiction|suspended animation]] and be awakened when they reached another star system. He proposed to use small moons or asteroids as ships, and speculated that the crew would endure psychological and genetic changes over the generations.<ref>Rodriguez Baquero, p. 16</ref>

[[Tsiolkovsky|Konstantin Tsiolkovsky]], considered a father of [[Astronautics|astronautic theory]], first described the need for multiple generations of passengers in his essay, "The Future of Earth and Mankind" (1928), outlining a space colony equipped with engines that travels thousands of years which he called "Noah's Ark". In the story, the crew had changed so much over the generations at so many levels that they did not even acknowledge Earth as their home planet.<ref>Rodriguez Baquero, p. 18</ref> 

Another early description of a generation ship is in the 1929 essay "The World, The Flesh, & The Devil" by [[John Desmond Bernal]].<ref name="BERNAL" /> Bernal's essay was the first publication to reach the public and influence other writers. He wrote about the concept of human evolution and mankind's future in space through methods of living that we now describe as a generation starship, and which could be seen in the generic word "globes".<ref name="BERNAL">{{cite web|url=http://bactra.org/Bernal/|title=The World, the Flesh & the Devil - An Enquiry into the Future of the Three Enemies of the Rational Soul|author=J. D. Bernal |year=1929 |access-date = 20 January 2016}}</ref>

== Definition ==
According to Hein et al., a "generation ship" is a spacecraft on which a crew is living on-board for at least several decades, such that it comprises multiple generations.<ref name="hein-pak-putz-revisited" /> Several sub-categories of generation ships are distinguished: sprinter, slow boat, colony ship, world ship.<ref name="hein-pak-putz-revisited" />
The [[Enzmann starship]] is categorised as "slow boat" because of the ''[[Astronomy Magazine]]'' title "Slow Boat to Centauri" (1977).<ref>{{cite web|url= http://www.icarusinterstellar.org/wp-content/uploads/2012/05/BISEnzmann-Talk-2011kflong.pdf|title= The Enzmann Starship: History & Engineering Appraisal|first1=K.F. |last1=Long |first2=A. |last2=Crowl |first3=R. |last3=Obousy|access-date= 7 February 2013|url-status= dead|archive-url= https://web.archive.org/web/20130124211710/http://www.icarusinterstellar.org/wp-content/uploads/2012/05/BISEnzmann-Talk-2011kflong.pdf|archive-date= 24 January 2013}}</ref> Gregory Matloff's concept is called a "colony ship" and [[Alan Bond (engineer)|Alan Bond]] called his concept a "world ship".<ref name="hein-pak-putz-revisited" /> These definitions are essentially based on the velocity of the ship and population size.<ref name="hein-smith-marin-wsfar" />

==Obstacles==

===Biosphere===
Such a ship would have to be entirely self-sustaining, providing [[life support system|life support]] for everyone aboard. It must have extraordinarily reliable systems that could be maintained by the ship's inhabitants over long periods of time. This would require testing whether thousands of humans could survive on their own before sending them beyond the reach of help. Small artificial closed ecosystems, such as [[Biosphere 2]], have been built in an attempt to examine the engineering challenges of such a system, with mixed results.<ref>{{cite web |url=https://www.vice.com/en/article/biosphere-2-how-a-sci-fi-stunt-turned-into-the-worlds-biggest-earth-science-lab/ |title=Biosphere 2: How a Sci-Fi Stunt Turned Into the World's Biggest Earth Science Lab |last=Merchant |first=Brian |date=June 10, 2013 |website=Motherboard |publisher=Vice Media LLC |archive-url=https://web.archive.org/web/20160819124432/http://motherboard.vice.com/blog/biosphere-2-how-a-sci-fi-stunt-turned-into-the-worlds-biggest-earth-science-lab |archive-date=August 19, 2016 |url-status=live }}</ref>

===Biology and society===
Generation ships would have to anticipate possible biological, social and morale problems,<ref name="Malik20020319">{{cite web|last1=Malik|first1=Tariq|title=Sex and Society Aboard the First Starships |url=http://www.space.com/scienceastronomy/generalscience/star_voyage_020319-1.html |url-status=dead |archiveurl=https://web.archive.org/web/20020407132242/http://www.space.com/scienceastronomy/generalscience/star_voyage_020319-1.html |archivedate=2002-04-07 |work=Space.com |date=19 March 2002}}</ref> and would also need to deal with matters of self-worth and purpose for the various crews involved.

Estimates of the minimum reasonable population for a generation ship vary. Anthropologist John Moore has estimated that, without [[genetic testing]] of people before boarding the ship, [[social control]] and / or [[social engineering (political science)|social engineering]] (such as requiring people to wait until their thirties to have children), nor [[cryopreservation]] of eggs, sperm, or embryos (as is done in [[sperm bank]]s), a minimum of 160 people boarding the ship would allow normal family life (with the average individual having ten potential marriage partners) throughout a 200-year space journey, with little loss of [[genetic diversity]]. If the people who board the ship are couples, presumably in their early twenties, and everybody who lives in the ship is required to wait until their mid to late thirties before having children, then the minimum would be just 80 people. However, many variables are not accounted for in the estimate, including the higher chance of health problems for both the woman who is pregnant and the fetus or baby because of the [[advanced maternal age|pregnant woman's age]].<ref>{{cite web |url=https://www.newscientist.com/article/dn1936-magic-number-for-space-pioneers-calculated/ |title="Magic number" for space pioneers calculated |date=15 February 2002 |author=Damian Carrington |work=[[New Scientist]] |access-date=6 August 2019}}</ref> In 2013, anthropologist Cameron Smith reviewed existing literature and created a new computer model to estimate a minimum reasonable population in the tens of thousands. Smith's numbers were much larger than previous estimates such as Moore's, in part because Smith takes the risk of accidents and disease into consideration, and assumes at least one severe population catastrophe over the course of a 150-year journey.<ref>{{cite journal|title=Smith, C.M., "Estimation of a genetically viable population for multigenerational interstellar voyaging: Review and data for project Hyperion" |journal=Acta Astronautica |volume=97 |pages=16–29 |date=2013-12-13 |doi=10.1016/j.actaastro.2013.12.013|bibcode=2014AcAau..97...16S|last1=Smith |first1=Cameron M. }}</ref>

In light of the multiple generations that it could take to reach even our nearest neighboring star systems such as [[Proxima Centauri]], further issues on the viability of such interstellar arks include:

* the possibility of humans dramatically [[evolution|evolving]] in directions unacceptable to the sponsors
* the minimum population required to maintain in isolation a culture acceptable to the sponsors; this could include such aspects as
** ability to learn scientific and technical skills needed to maintain, operate and pilot the ship
** ability to accomplish the purpose (planetary colonization, research, building new interstellar arks) contemplated
** sharing the [[values]] of the sponsors, which may not be likely to be empirically demonstrated to be viable beyond the home planet unless, once the ship is away from Earth and on its way, survival of one's offspring until the ship reaches the target star is one motivation.

===Size===
For a spacecraft to maintain a stable environment for multiple generations, it would have to be large enough to support a community of humans and a fully recycling ecosystem.<ref >{{cite arXiv | last1=Marin | first1=F. | last2=Beluffi | first2=C. | title=Computing the minimal crew for a multi-generational space travel towards Proxima Centauri b | date=2018 | class=astro-ph.IM |eprint=1806.03856}}</ref> A spacecraft of such a size would require much energy to accelerate and decelerate. A smaller spacecraft, while able to accelerate more easily and thus make higher cruise velocities more practical, would reduce exposure to cosmic radiation and the time for malfunctions to develop in the craft, but would have challenges with resource metabolic flow and ecologic balance.<ref>{{cite web |author1=Kim Stanley Robinson |title=What Will It Take for Humans to Colonize the Milky Way? |url=https://www.scientificamerican.com/article/what-will-it-take-for-humans-to-colonize-the-milky-way1/ |work=[[Scientific American]] |access-date=January 31, 2019 |language=en |date=January 13, 2016}}</ref>

===Social breakdown===
Generation ships traveling for long periods of time may see breakdowns in social structures. Changes in society (for example, mutiny) could occur over such periods and may prevent the ship from reaching its destination. This state was described by [[Algis Budrys]] in a 1966 book review:<ref name="budrys196608">{{Cite magazine
 |last=Budrys
 |first=Algis
 |date=August 1966
 |title=Galaxy Bookshelf
 |url=https://archive.org/stream/Galaxy_v24n06_1966-08#page/n185/mode/2up
 |magazine=Galaxy Science Fiction
 |pages=186–194
}}</ref>

{{quote|The slower-than-light interstellar spaceship, pursuing its way through the weary centuries, its crew losing touch with all reality save the interior of the vessel ... Well, you know the story, and its unhappy downhill round, its exciting struggles between the barbarian tribes which develop in its disparate compartments, and then, if the writer is so minded, the ultimate flash of hope as the good guys win out and prepare to meet their future on some noble, if erroneous basis.}}

[[Robert A. Heinlein]]'s ''[[Orphans of the Sky]]'' (the "impeccable statement of this theme", Budrys said){{r|budrys196608}} and [[Brian Aldiss]]'s [[Non-Stop (novel)|''Non-Stop'']] (U.S. title: ''Starship'') discussed such societies.

===Cosmic rays===
{{Main|Health threat from 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 influx of high-energy [[galactic cosmic rays]] (GCRs). Like other [[ionizing radiation]], high-energy cosmic rays can damage DNA and increase the risk of cancer, cataracts, and neurological disorders.<ref>{{cite web|url=http://spaceflight.nasa.gov/spacenews/factsheets/pdfs/radiation.pdf |archive-url=https://web.archive.org/web/20041030191015/http://www.spaceflight.nasa.gov/spacenews/factsheets/pdfs/radiation.pdf |url-status=dead |archive-date=2004-10-30 |title=NASA Facts: Understanding Space Radiation |access-date=2010-04-01}}</ref>

==Ethical considerations==
The success of a generation ship depends on children born aboard taking over the necessary duties, as well as having children themselves. Even if their quality of life might be better than, for example, that of people born into poverty on Earth, philosophy professor Neil Levy has raised the question of whether it is ethical to severely constrain life choices of individuals by locking them into a project they did not choose.<ref>{{cite web|url=https://aeon.co/ideas/would-it-be-immoral-to-send-out-a-generation-starship|title=Would it be immoral to send out a generation starship?|last=Levy|first=Neil|date=13 June 2016|work=[[Aeon (digital magazine)|Aeon]]|access-date=26 June 2019}}</ref> A moral quandary exists regarding how intermediate generations, those destined to be born and die in transit without actually seeing tangible results of their efforts, might feel about their forced existence on such a ship.

==Project Hyperion==
[[Project Hyperion (interstellar)|Project Hyperion]], launched in December 2011 by Andreas M. Hein, was to perform a preliminary study that defines integrated concepts for a crewed interstellar generation ship. This was a two-year study mainly based out of the [[WARR (research group)|WARR]] student group at the [[Technical University of Munich]]. The study aimed to provide an assessment of the feasibility of crewed interstellar flight using current and near-future technologies. It also aimed to guide future research and technology development plans as well as to inform the public about crewed interstellar travel.<ref>{{Cite web|last=Interstellar|first=Icarus|date=2020-12-06|title=Icarus Interstellar, Interstellar flight|url=http://www.icarusinterstellar.org/projects/project-hyperion|access-date=2020-12-07|website=Icarus Interstellar|language=en|archive-date=2020-12-14|archive-url=https://web.archive.org/web/20201214085530/http://www.icarusinterstellar.org/projects/project-hyperion/|url-status=dead}}</ref><ref>{{Cite web|last=DNews|title=Icarus Interstellar: Visions of Our Starship Future|url=https://www.seeker.com/icarus-interstellar-visions-of-our-starship-future-1769714561.html|access-date=2020-12-07|website=Seeker|date=10 April 2015 }}</ref> Notable results of the project include an assessment of world ship system architectures and adequate population size.<ref name="hein-pak-putz-revisited" /><ref>{{cite journal |last1=Smith |first1=Cameron M. |title=Estimation of a genetically viable population for multigenerational interstellar voyaging: Review and data for project Hyperion |journal=Acta Astronautica |date=2014 |volume=97 |page=16-29 |doi=10.1016/j.actaastro.2013.12.013 |bibcode=2014AcAau..97...16S |url=https://www.sciencedirect.com/science/article/pii/S0094576513004669|url-access=subscription }}</ref> The core team members have transferred to the [[Initiative for Interstellar Studies]]'s world ship project and a survey paper on generation ships has been presented at the [[European Space Agency|ESA]] Interstellar Workshop in 2019 as well as in [[European Space Agency|ESA]]'s Acta Futura journal.<ref name="hein-smith-marin-wsfar">{{cite journal |last1=Hein |first1=Andreas M |last2=Smith |first2=Cameron |last3=Marin |first3=Frederic |last4=Staats |first4=Kai |title=World Ships: Feasibility and Rationale |journal=Acta Futura |date=2020 |volume=12 |page=75-104 |doi=10.5281/zenodo.3747333 |arxiv=2005.04100 |s2cid=218571111 }}</ref><ref>{{cite web |last1=Faife |first1=Corin |title=Scientists Are Contemplating a 1,000-Year Space Mission to Save Humanity |url=https://onezero.medium.com/scientists-are-contemplating-a-1-000-year-space-mission-to-save-humanity-70882a0d6e47 |website=Medium - OneZero |date=17 December 2019 |access-date=14 February 2021}}</ref><ref>{{cite web |last1=Hein |first1=Andreas M |last2=Smith |first2=Cameron |last3=Marin |first3=Frédéric |last4=Staats |first4=Kai |title=World Ships –Feasibility and Rationale |url=https://indico.esa.int/event/309/attachments/3517/4683/World_Ships_-_Andreas_Hein.pdf |access-date=16 February 2021}}</ref>

==See also==
*[[Aniara]]
*[[Autarky]]
*[[Embryo space colonization]]
*[[O'Neill cylinder]]
*[[Self-replicating spacecraft]]
*[[Sleeper ship]]
*[[Stanford_torus#World_ship_proposal|World ship proposal based on Stanford torus]]

==References==
{{reflist}}

==Further reading==
* Caroti, Simone (2011). “The Generation Starship in Science Fiction: A Critical History, 1934-2001” Mcfarland. {{ISBN|978-0-7864-6067-0}}.
* {{cite journal |last1=Hein |first1=Andreas M. |last2=Pak |first2=Mikhail |last3=Pütz |first3=Daniel |last4=Bühler |first4=Christian |last5=Reiss |first5=Philipp |title=World ships—architectures & feasibility revisited |journal=Journal of the British Interplanetary Society |date=2012 |volume=65 |issue=4 |page=119|url=https://www.researchgate.net/publication/236177990 }}
* {{cite book |last= Rodriguez Baquero|first= Oscar Augusto|date= 2017|title= La presencia humana más allá del sistema solar|trans-title= Human presence beyond the solar system|url= |language= Spanish|location= |publisher= RBA|isbn=978-84-473-9090-8}}

== External links ==
* {{cite web|url=https://www.projecthyperion.org/|title=Project Hyperion|access-date=3 November 2024|date=1 November 2024}}
* {{cite web|url=http://strangepaths.com/interstellar-ark/2007/02/14/en/|website=Strange Paths: Physics, computation, philosophy|title=Interstellar Ark|author=Gilgamesh|access-date=13 February 2015|date=14 February 2007}}
* {{cite web|url=http://www.centauri-dreams.org/?p=19423|website=Centauri Dreams: Imagining and Planning Interstellar Exploration|title=Worldships: A Interview with Greg Matloff |first=Paul|last= Gilster|date=17 August 2011|access-date = 9 February 2013}}
* {{cite web|url=http://www.icarusinterstellar.org/project-hyperion-the-hollow-asteroid-starship-dissemination-of-an-idea/|website=Icarus Interstellar|title=Project Hyperion: The Hollow Asteroid Starship – Dissemination of an Idea|first=Andreas|last=Hein|date=13 May 2012|access-date=13 February 2015|archive-date=10 April 2013|archive-url=https://web.archive.org/web/20130410004948/http://www.icarusinterstellar.org/project-hyperion-the-hollow-asteroid-starship-dissemination-of-an-idea/|url-status=dead}} Brief summary of the evolution of generation ship concepts.
* {{cite web|last1=Nicholls|first1=Peter|last2=Langford|first2=David|title=Generation Starships|url=http://www.sf-encyclopedia.com/entry/generation_starships|website=The Encyclopedia of Science Fiction|publisher=Gollancz|access-date=13 February 2015|location=London|date=5 April 2014}}

[[Category:Space colonization]]
[[Category:Hypothetical spacecraft]]
[[Category:Fictional spacecraft by type]]
[[Category:Interstellar travel]]
[[Category:Fiction about generation ships| ]]
[[Category:Science fiction themes]]
[[Category:Space farming]]
[[Category:Self-sustainability]]