Design Overview Edit
The vehicle is a cylindrical interstellar ark, peopled with a colony of humans who have departed on the first one-way voyage toward the Alpha Centauri system. The blueprint for orbital construction of such a futuristic starship was conceived by Ahad in 2004 and incorporated in the first and second novels in his First Ark series.
The outer dimensions of the bullet shaped body are 12 miles (length) x 7 miles (diametric width), grossing a total mass estimated to be of the order of 1.48 x 10^14 kg (equivalent to some 10% of that of the Martian moon Deimos).
The interior is a cylinder of dimensions approx. 9 miles (length) by 6 miles (width) with use of an artificially maintained, yet naturalised, ecosystem. Therefore the environment mirrors that of a "miniature Earth" inside.
The vehicle design and launch trajectory for its 50,000 year projected interstellar spaceflight duration is covered below.
Voyage Blueprint Edit
Architecture and EngineeringEdit
The engineering process for on-orbit construction of the Ark is briefly covered in First Ark to Alpha Centauri (the novel) in chapters 1 and 9. The outer body is made up of a robust metallic alloy in a matrix of the elements carbon and titanium, fused together with steel. Hence the abbreviation 'CST' is used to refer to this synthetic in the novels.Through rotation of the Ark along its longitudinal spin axis, the vessel's interior maintains 1g of Earth gravity along the curved walls of the cylinder. The nominal rotation period of the Centauri Princess is 2 minutes 22 seconds. This gives a nominal RPM of ~0.4, which is substantially below the 2 RPM level above which coriolis forces are thought to cause harmful side effects upon the human physiology.
Material was harvested from an Earth-captured asteroid and then robotically maneouvered into place to build the basic framework of the Ark, over a timescale of some 25 years in the 2250 to 2275 AD era in Earth's future based on the current Gregorian calendar.
The dimensions of the cylindrical biosphere were carefully architectured such that the total available surface area for habitation would match a population density of present day Earth's. This was made clear in a 2008 Myspace blog published by the author. The effective surface area of the Ark's habitable 'floor' is 437 square kilometers (as shown in the diagram on the right). On page 143 of First Ark to Alpha Centauri, it states that the Centauri Princess shall have an upper limit on population of 5,000 people. Therefore dividing 437 by 5000 gives a mean population density of 0.087 square km's of surface area per capita (per person).
This matches present day Earth's figures: Total surface area = 510 million square kilometres (land + oceans put together). Current world population = 6 billion people. Therefore, mean population density = 510,000,000/6,000,000,000 = 0.085 square km's of surface area per capita (per person).
In the original research thesis that was self-published by Ahad, in August 2004, the environment was designed around a Controlled Ecological Life Support System (CELSS). Lighting is provided across the interior by mounting sun-simulating light bulbs ('miniature suns' as described in the novels) on transparent pedestals and supplied with current and voltage via cables that run along them. Through the additive properties of light, making their conical illuminations overlap between individual lights, one gets the simulated ambience of perfect sunshine. Tree roots would grow in the direction of centrifugal forces down into the soil, and their shoots would grow in the opposite (centripetal) direction toward the minitaure suns, much the same as how things are here on Earth.
The Centauri Princess has an onboard nuclear power station, utilising a fission reactor, to meet the energy demands for all biosphere functions.
All the automated processes that contribute to the workings of the biosphere, such as control of lighting and heating on a diurnal as well as seasonal basis, are handled by pre-programmed modules built into the Ark ship's central computer, CPC. This also entails the simulation of thunderstorms across the interior and the momentary dimming of lighting levels to mimic dark and overcast skies, the sweeping of violent gales, etc, as seen on Earth all done by CPC coordinating the movements of the twenty weatherbots suspended 3 miles up along the central sky-length of the cylinder.
For initial departure from high Earth orbit, the equations of motion in the n-body problem of celestial mechanics were numerically integrated, treating the Ark to be exactly the same as a natural cometary body, except that it was moving under conditions of powered flight from a closed orbit around the Earth toward a heliocentric orbit about the Sun.
In total, the Centauri Princess had spent several decades within the outer Solar System, awaiting successive rendezvous opportunities with Jupiter and Saturn. Its velocity was incremented through a number of gravitational slingshots to achieve the final velocity needed to depart from the Sun's sphere of gravitational influence. Ahad had first imagined how this could be done by supposing that if the Voyager spacecraft could achieve this solely by relying on gravitational swingby's of Jupiter and Saturn, then so could a gigantic manned vehicle and popped the question on his favourite science forum.
The propulsion and thrust components were 'assumed' parameters, since no man-made engineering currently exists in the real world to be able to validate the dynamical escape sequence required to achieve Solar System escape velocity with any degree of mathematical rigor. This was first raised by Ahad with his scientific colleagues on usenet forums, e.g. "Escape timelines for my interstellar ark".
Voyage Duration Edit
"The 50,000 year long voyage duration I am projecting is what I like to call a "least-propulsive energy requirement versus most-safe, optimisation". If the ark moves much slower and it takes any longer than this order of timescale, you can see that Alpha Centauri will soon start to drift out of range, and the vehicle will be playing 'catch up' with its destination. If it speeds much faster, and aims to reach Alpha Centauri in say just 5,000 or 10,000 years from now, then the craft will need a lot more propulsive energy on its way out of our Solar System, suffer major impacts from any Oort cloud bodies [that may be] encountered en-route and also require excessive delta-v at the other end in order to slow right down and successfully rendezvous with New Earth." - Abdul Ahad (2006)
The mass and volume optimisations are governed by the need to have a biosphere that is large enough to permit weather, cloud formations and rainfall, yet small enough to be movable with any conceivable amount of propulsive force to achieve Solar System escape velocity. Propelling a 12-mile long Centauri Princess (of comparatively miniscule size/mass) on its way to Alpha Centauri is more rationally feasible than say shifting an entire asteroid the colossal size of Ceres (of 600-mile diameter) from the asteroid main belt.
In-Flight Resourcing Edit
Based on original research by Abdul Ahad in 2004, where he first hypothesised shells of overlapping Oort cloud debris to be encircling both our Sun and Alpha Centauri, the likelihood has been anticipated in this voyage of the availability of water-ice and chemical volatiles along the way. It was also argued by the author that it would be necessary to top up a biosphere - especially with water - which would otherwise run dry over timescales running into 50 millennia.
There are two methods whereby the Ark ship's biosphere may be topped up with additional oxygen and life supporting ingredients:-
- In-flight disintegration of material ahead of the Ark
- Scooping up by landing robotic probes
Both these methods were proposed by Ahad in the original scoping of the voyage, and both remain in the sphere of original research to date. Perhaps the more feasible of the two would be the former method. It entails targeting a cluster of nuclear missiles, launched from the Centauri Princess' Missile Bay (at the front of the Ark), which disintegrates a cometary body in front of the ship. Then, as the Ark passes through the partially ionised debris cloud, material is attracted using a magnetic funnel, channelled into the interior via pipelines and reconstituted into normal matter. This is discussed in more detail on pages 78-80 of First Ark to Alpha Centauri.
The suggestion here is much like how the magnetic field of the Earth traps charged particles coming from the Sun (the Solar wind). In the same way, the ionised plasma disintegrated in front of the Centauri Princess is attracted by the magnetic funnel, with a remote possibility of some of it being reconstituted from ionic form back into molecular form - with inevitable losses of mass along the way.
Provisions for EVAs Edit
There are a whole variety of reasons why people would need to go on extravehicular activities (EVAs) and spend time outside the Earth-like environment provided for inside the Ark.
There are two modes of transport to go for EVAs: the space shuttles and the Oort cruiser.
Geography of the Interior Edit
The cylindrical interior is split 50-50 into two provinces: Upper Province and Lower Province, respectively, with various features ranging from the residential town of Utopia, with its streets and houses to forests, meadows, lakes and the ever meandering Eridanus river.
The instantaneous "cylindrographical" coordinates of people as they roam around the interior, and fixed places alike, are mapped using the 3D cylindrical coordinate system of analytical geometry.
For individual residents of the Ark, as they roam around the interior, the wristcom acts in much the same way as a present day GPS device, which maintains 2-way telemetry links with overhead weatherbots. This helps the wristcom triangulate a continuous set of coordinates for a person, which is monitored by CPC for security reasons. Criminal behavior is minimised using this regime, since offenders can be located and tracked down with pinpoint accuracy 24 hours a day, seven days a week. No matter where they may choose to roam across the interior, they are always within visibility range of overhead weatherbots, and hence CPC.
The Farming Complex is a dedicated area of land where all the food is grown inside astroculture domes as well as outdoor open areas, which includes rice fields. It sits in the starship's Lower Province.
Links to Published Sources Edit
- First Ark to Alpha Centauri (2005 Novel)
- First Ark to Alpha Centauri 2 (2006 Novel)
- Review in The Daily Star
- Abdul Ahad's Myspace Blogs