Interstellar ark

An interstellar ark is a conceptual space vehicle that some have speculated could be used for interstellar travel. Interstellar arks may be the most economically feasible method of traveling such distances.

An interstellar ark must be a sleeper ship instead of a generation ship because of energy constraints.

Considerations for sleeper-ship proposals

A sleeper type crewed starship would probably be propelled by a Daedalus type fusion microexplosion nuclear pulse propulsion system, that may allow it to obtain an interstellar cruising velocity of up to 10% of the speed of light. However, if the ship is capable of transits requiring hundreds of thousands of years, chemical and gravitational slingshot propulsion may be sufficient.

At the present time, cryopreservation and other forms of "cold sleep" lasting decades or longer are only theoretical possibilities, as it is currently impossible to reverse the process of cryopreservation. These possibilities are suggested by the short-term hibernation of certain mammalian species and the advancing technology of Cells Alive System-type freezers. Hypothermia and hibernation can greatly reduce the amount of food, water, and oxygen required to keep a human (or any other animal) alive while in stasis (suspended animation/induced hibernation). Developing the medical technology that is required to achieve a "sleeper" type starship may theoretically be an achievable goal for late in the 21st century, depending on funding and laboratory experiments.

The appeal of these methods rests on hopes of:

• reducing ship mass by eliminating the equipment needed by an active ship-city population (without cold-sleep-maintaining and -reversing equipment of comparable mass), and/or
• avoiding the need for an acceptable ark-adapted culture.

Orbital habitat

The ark has also been proposed as a potential habitat to preserve civilization and knowledge in the event of a global catastrophe.

Enzmann starship

Main article: Enzmann starship

In 1964, Robert Enzmann proposed a large fusion powered spacecraft that could function as an interstellar ark, supporting a crew of 200 with extra space for expansion, on multi-year journeys at subluminal speeds to nearby star systems.

Fiction

• The 1933 novel When Worlds Collide is one of the earliest examples of an interstellar ark. To save humanity from extinction when a star is about to destroy Earth, a group of astronomers construct a massive spaceship to carry forty humans, in addition to livestock and equipment, to a new planet.

• Jack Williamson's 1934 story "Born of the Sun" is another early example, in which planets are revealed to be no more than eggs for immense creatures. A steel magnate and his geologist/astrophysicist uncle create an "ark of space" to preserve the human race in the six months left in the Earth's existence. The ark is designed to hold two thousand people, be powered off of cosmic rays, and to recycle water and waste to create synthetic food and air, thus providing for an unlimited survival of its crew in space.

• A group of three large arks served as the homes and battleships of the space-faring Thraki race in William C. Dietz's Legion of the Damned series.

• The concept of an interstellar ark was used humorously in the cult sci-fi classic The Hitchhiker's Guide to the Galaxy, in the form of the B-Ark of the Golgafrincham Ark Fleet, filled to capacity with cryosleeping advertising executives, management consultants, independent filmmakers, and other "undesirables" whom the Golgafrinchams wanted to expel. Hitchhiker's Guide author Douglas Adams had first proposed these plot elements for a TV special that was to have featured Ringo Starr, but the show was never produced.

• The Starlost is a television series about a generation ship lost in space, whose inhabitants had forgotten that they were on a ship.

• In the PC game Outpost series, an interstellar ark named Conestoga was used to evacuate a population of humans from the impending destruction of Earth.

• The PC game Alien Legacy features "seedships", used to spread mankind due to an interstellar war that might wipe out the Earth.

• The SS Botany Bay was a sleeper ship used by Khan Noonien Singh in the Star Trek first season episode "Space Seed".

• A Star Trek third season episode entitled "For the World Is Hollow and I Have Touched the Sky" takes place on a hollow asteroid generation 'ship' called Yonada.

• The Centauri Princess is a cylindrical interstellar ark peopled with humans, depicted in elaborate detail in the novel First Ark to Alpha Centauri by A. Ahad

• The cylindrical generation ship Vanguard serves as the centerpiece of Robert A. Heinlein's 1963 novel Orphans of the Sky, a combination of two shorter 1941 works.

• In the animated Disney-Pixar film WALL-E, the space vessel Axiom, originally intended as a temporary dwelling for humanity for a 5 year period during which robots were to clean up an environmentally devastated Earth, becomes a de facto ark housing multiple generations of humans over a period of 700 years.

• In Stargate Atlantis third season episode "The Ark", Colonel Sheppard's team discovers a facility inside a hollowed-out moon that turns out to be an ark created by the people of the planet around which the moon is in orbit. The ark was built to preserve the existence of the people from the planet and rebuild its civilization after a Wraith defeat. People were stored in stasis in the ark using Wraith beaming technology. The government then waged an unwinnable war against the Wraith, and purposely decimated the remainder of their own population with atomic bombs, leading the Wraith to believe that these people are extinct.

• Episode 30 of the radio drama Dimension X, "Universe", featured a seed ship whose human population had split into the lower deck inhabitants and the upper deck inhabitants. The upper deck inhabitants were mutated by radiation leaking through the ship's hull. The inhabitants were not aware they were on a ship and believed the vessel contained the entirety of the universe. The episode was written by Robert A. Heinlein.

• In the Warhammer 40,000 fictional universe, the Eldar race live and travel aboard interstellar arks, Craftworlds

• In Rendezvous with Rama, by Arthur C. Clarke, an alien interstellar ark transits through Earth's solar system.

• New Zealand author Ken Catran creates the novel trilogy Deepwater_trilogy a science fiction adventure for young adults about a massive generation ship "Deepwater Black" created by the dying population of a virus stricken Earth. The main inhabitants are teen clones all creaded from gene donors, all of which contributed to Earth society in phenomenal ways. As they travel on, they must survive the unknowns of space as well as the insecurities of being clones with the genetic memories of their dead donors constantly resurfacing in their heads. The novels were made into a 13 episode series for YTV and SciFi Channel in 1997

• In Hull Zero Three, by Greg Bear (2010), an interstellar ark is equipped with a library of biological forms and generates customized individuals as needed during its voyage.

• The 2009 film Pandorum is set on an interstellar ark called Elysium. Originally sent into space to seed a new world after the destruction of Earth, the ship has fallen into disarray and is largely overrun by a mutated subspecies of cannibalistic humans.

Considerations for generation ship proposals

Such a ship would have to be large, and the only adequate technology likely to be available (even assuming the most favorable economic and political factors) soon enough to make plans is the Orion concept of propulsion by nuclear pulses. The largest spacecraft design analyzed in the Orion project had a 400 m diameter and weighed approximately 8 million tons. It could be large enough to host a city of 100,000 or more people.

The purely engineering issues concern building, in space, a physically self-sufficient craft. Another concern is selection of power sources and mechanisms which would remain viable for the long time spans involved in interstellar travel through the desert of space. The longest lived space probes are the Voyager program probes, which use radioisotope thermoelectric generators having a lifespan of a mere 50 years.

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

• the possibility of humans dramatically 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 maintain and operate the ship
  • ability to accomplish the purpose (planetary colonization, research, building new interstellar arks) contemplated
  • sharing the values of the sponsors (which are not likely to be empirically demonstrated to be viable beyond the home planet).

External links

• Interstellar Ark Mission Architectures and Various Feasibility Issues
• More on Interstellar travel
• News article
• Lifeboat Foundation
• More thoughts on the Interstellar Ark