====== Introduction to the Ship ======

Excerpted from //The Manual//, a reference for the intrepid generationalist:

==== The Asimov ====

//9 million tonnes of spinning metal hurtling through the night. \\
All that stands between humanity and extinction. \\
**Home**.//

//Over the years it has undergone so many modifications and malfunctions. No one, not even Computer, knows the entirety of it now. This guide is an attempt to codify the essential information for anyone leaving their home sector, for it is clear to even the casual observer that beyond being designed by different people, the ship is now inhabited by different people.//
  
==== Naming Conventions ====

{{ :ship-topdown.png?200}}

Over the years many different taxonomies for naming the different parts of the ship have been proposed. However, this guide will use the now widely accepted Toroid-Sector-Compartment naming:
  * Each of the ship's large spinning sections is referred to as a **Toroid** (a ring-like shape, also known as a doughnut). We number from Toroid 1 at the shieldwards end, through Toroid 5 at the drivewards end. While some toroids are almost cylindrical in reality, the human spaces lie within the outer 20% --- making them toroidal for most purposes.
  * Imagine each toroid having evenly distributed sections inscribed within a circle 3.1km in circumference. Each is a **Sector**, with between 5 and 12 sectors for each Toroid, seemingly on the designer's whim. Many of these sectors are filled with machinery or are otherwise inaccessible, leaving a smaller number of main residential sectors in each Toroid.
  * Each division of a sector that can be individually sealed by the Computer in the event of a vacuum event is assigned a designator (often numerical) by the Computer. Each of these divisions is called a **Compartment**.
 
Directions are slightly more complicated than they first appear. While //front// and //back// or //bow// and //stern// may seem obvious to us at present, the legend of the flip has led many to decry such absolute names as heresy. As such it has become commonly accepted to instead use the terms //drivewards// and //shieldwards// to refer respectively to the direction the engines are pointing and the direction towards the ablation shield at the opposite end of the core.
The phrase //down// is used to mean the direction of apparent gravity. Down always coincides with the outside of the toroid, so the core is always "above" you. Compartments have curved floors such that "down" is always normal (perpendicular) to the floor.

==== The Toroids ====

The five toroids are all of a similar size, as far as anyone can tell. Standing on the lowest level, the ship's central core is half a kilometer above your head. The inhabited areas typically fill around 33 floors ranging from a full G to only 80% gravity, though despite the limited space, each inhabited toroid plays host to approximately between 50,000 and 60,000 citizens split roughly evenly across each sector. The remaining low gravity space is taken up by the ship's internal machinery and storage space. If one were to remove all the walls one would reveal that the drivewards length is a mere 100m. And if you had a window and a reference point, you would be dizzied by the fact that you complete a full revolution around the core once every 45 seconds, or rather that you are traveling at 125 kph. Fortunately no-one puts windows in the floor.

**Toroid 1** consists of 6 sectors, and is the home of civilization on the ship. Notably this is the location of Green, Rainbow and Yellow Sectors. \\

**Toroid 2** also has 6 sectors, including Red and the slightly more downmarket "Blackout" and Blue Sectors. It also sports the largest Oxygen Forest, one of the ship's great wonders. \\

**Toroid 3** Was reputedly a massive open forest and park, filled with all of the various plant samples that were sent with the ship as well as various insects. This Toroid has been sealed off due to some unknown disaster some 200 years ago. \\

**Toroid 4** has been designated uninhabited and restricted. Computer seems to use it as a large storage area, and it appears to be generally inaccessible. Rumours persist that it is home to black market activity, and people trying to live outside the beneficence of Computer. Clearly, that's not true. \\

**Toroid 5** is a designated hazard zone. Ever since the Great Burn of Mission Year 243 radiation levels are sufficiently high that Computer limits access to this toroid. Those who survived The Great Burn were rehoused in parts of Toroid 2, but the unfortunate incidence of continued medical problems even in more recent generations has meant that their population has dwindled significantly. Rumours of //other// things that inhabit the toroid have never been conclusively proven, but nor have they been effectively denied.
==== The Core ====

//Roughly 100m in cross section and 850m long, the core is critical to the design of the ship. As the core has zero angular momentum, there is no simulated gravity; further the core is open to space at the driveward end. In summary, it's as close as any crew member is going to get to being in space this side of the ablation shield. Each toroid's four balanced vector thrust units are locked in a rearwards position for the standard operation configuration. Toroid 2's thrust units are staggered at an offset from those of toroid 1, and toroid 3's from both those of toroids 1 and 2 and so forth such that the particle plumes have a clear path out to the rear of the ship so they can operate with maximal efficiency and minimal collateral damage. As such usable core space decreases significantly as you head in a drivewards direction. The free space is occupied by the human and inanimate inter-toroidal transport systems essential to resource balancing. The motion of such items from one toroid to another necessitates careful manipulation of angular momentum, which is achieved using automated ballasting, yet another critical system taking up the premium space. A small area has been set aside forwards of toroid 1 and behind the ablation shield for zero gee manufacturing and other such endeavours that cannot be housed on the toroids themselves. // \\
--- Engineering Technical Manual

//The total volume of the core is about 3% that of Red Sector. In that space the entire guts of the ship's inter-toroidal transport system, momentum compensation, plumbing, and zero-G manufacturing facilities have to fit around the engine exhausts. Stay away from those kids, they may not look hot, but that's because in a vacuum there are no excited particles emitting light. Stick your arm in there, and you will have a few seconds of extreme pain as your space suit disintegrates due to bombardment by billions of particles per second striking at a significant fraction of the speed of light. And then some idiot decided to try and fit Null-Grav Football pitches in there too! Well, the net result is no-one is going drivewards of toroid 4 through the main accessway, the whole thing's been sealed off.// \\
--- Traditional Engineering briefing to new apprentices before touring the core.
==== Getting about ====

=== Between Toroids ===

//For reasons of safety and the need for compensation of angular momentum, inter-toroidal travel is restricted without authorisation.// \\
--- The Computer

As toroids are counter rotating, the only way to transfer between them is through the central core. While transferring between a rotating toroid and the central core, a traveler is required to shed or gain significant angular momentum. This is normally safely accomplished through use of a special transfer capsule that Computer is able to smoothly pass through the slots between core and toroid when they briefly align once per rotation. The alternative, a manually timed leap through the momentarily aligned gap is not recommended for reasons of health and safety --- failure to correctly time one's jump is often fatal. Travel within the core is by a train that weaves its way between the majestic guts of the ship, avoiding the ion drive exhausts that also thread their way through the central core. Once at one's destination toroid the reverse process of transference between the central core and toroid is performed. 

=== Within Toroids ===

Citizens are able to travel freely within their own toroid. Each toroid has a small number of AD (ascent/descent) shafts that lead all the way from the outer edge to the central core. Rather than being straight these shafts curve to allow for the Coriolis effect as moving along them requires the gain or loss of angular momentum. In the event of power loss or power restriction ladders supplement the mechanical lift carriages. 

Other methods of transport vary within sectors, from bicycles to moving walkways.

=== Outside ===

There is no need for citizens to leave the ship until it reaches its intended destination. No external doors have been discovered on board, leading many of the crew to doubt it is possible to venture outside the ship. There are also no windows, though Computer will happily call up a simulated view of the outside on request.
==== Architecture ====

The architecture of the ship varies significantly depending on the original designs and modifications made by local residents; however, careful study of the general layout shows two distinct basic building patterns. As you know, each sector is a giant metal box, tapering towards the core, with occasional structural members and drop shafts running through it.

The first building pattern just leaves the sector be. This is exhibited most clearly in the Oxygen Forests of Toroid 2: two entire sectors that are nothing but vast open voids, with the tallest trees only just topping the 0.8g limit. (Of course, contrary to popular opinion it is the phytoplankton in each toroid's tank farms that generate most oxygen used on the ship.)

The second building pattern subdivides the second into compartments using internal partitions. A wide variety of sizes and geometries can thus be accommodated. The vast majority of the ship has been laid out in this way. Of course, a few sectors cheat and combine the two opposing styles, generating unique results such as the bizarrely named "sky scraper" of White Sector, a name whose origin is lost in the mists of time.