The Authorized Ender Companion

by Black, Jake

  The design of the Battle School represents a mixed-approach to the creation of artificial gravity. Normal living quarters and general use areas were designed to provide nominally 1G (Earth-normal) gravity. The Battle Rooms were placed in the stationary central core to provide a reliable zero-gravity environment. The gravitational acceleration on board the Battle School is produced in one of two ways: either through the use of centripetal acceleration from large, revolving habitation rings, or through the use of electro-synthetic planar gravity generators in the central core. For reasons touched upon earlier, all large-scale, long-duration mission space assets (such as interstellar ships, and the Battle School) were intentionally designed to rely on these two independent systems of artificial-gravity generation. In the event of the failure of one system, the other system remains intact, and can provide the necessary gravitation needed for the occupants of the ship or the space station.

  The two rotating habitation rings are each nominally 350 meters in diameter and 33 meters wide. These are exterior dimensions, and account for structural wall thickness, plumbing, piping, power and data, radiation shielding, and the like. The interior, usable dimensions are therefore smaller by approximately 3 meters per exterior wall and 5 meters for the exterior perimeter (the outer hoop). Interior walls and floors are of a more standard construction, and typically take up 0.5 meter and 1.5 meters respectively.

  These dimensions place the first level in the habitation ring at nominally 340 meters diameter (170 meters radius). The nominal height of each floor is 2.5 meters (8 feet). Allowing for floor thickness provides for roughly 3.0 meters (9.8 feet) per floor.

  The teachers’ quarters are placed along the outermost floor. Most of the support staff are also housed on this deck. The gymnasiums and related exercise rooms are located on the second level. Due to equipment requirements, the floor height for the second deck is increased from 2.5 meters to 3.5 meters (11.5 feet). The next four levels (A through D decks) are reserved for the student soldiers. Mess halls are also located on A Deck. Elevators and escalators provide quick access between decks. Ship’s ladders and descent poles are also provided as a secondary means of moving between floors.

  Six independent banks of elevators ascend from the outer habitation rings and feed into the central rotating disk. The central disk provides an additional series of concentric circular deck corridors that serve as station platforms for the shuttle cars that run between the rotating portions of the Battle School and the stationary central core. The outermost such deck is also the location of the “Game Rooms,” a collection of strategy-based video and holographic electronic games that are made available to the students of the Battle School.

  Because of the varying radii of all these decks, the centripetal gravitational acceleration is different on each one. The rotational speed of the habitation rings has been selected such that Student Deck D experiences 1G (Earth-normal) gravity. The gymnasiums see 104 percent Earth-normal gravity, and the Teacher’s Deck sees 109 percent Earth-normal gravity. The Game Room Deck, the outermost deck available for accessing the shuttle cars, has a nominal radius of 79 meters, and therefore sees approximately 51 percent (just over half) Earth-normal gravity. The mechanical requirements of the subway cars force the radial spacing between these more central decks to be on the order of 5.5 meters.

  The rings rotate at approximately 2.4 rpm (25 seconds per revolution), and have a tangential speed of 44 meters per second (m/s) (98 miles per hour, or 144 ft./sec.) at their circumference.

  The rings revolve against a pair of physical bearings set into the central core. The bearings present friction into the system, and therefore require additional energy to keep the rings spinning. However, the alternate—electromagnetic “floating” bearings—would have required more energy to maintain, and presented an unacceptable failure mode (loss of energy results in the rings binding up against the central core, causing a sudden and catastrophic deceleration). Because of the large size (nominally 180 meters diameter) of these physical roller bearings, the radial loads caused by the subtle eccentricities in the dynamic weight distribution of the rings results in minimal stresses in the bearing. Estimated bearing life for each of the four main bearings in the Battle School is greater than a hundred years’ continuous duty, with proper maintenance and lubrication. The bearings are sealed to assist in maintaining a proper pressure differential across them to contain the 80 percent atmospheric pressure within the Battle School. Additional rotating seals are provided adjacent to the bearing interface in order to maintain this pressure differential and provide redundancy.

  In order to maintain the proper speed and synchronization of the two rings, large direct-drive torque motors are built into the interface between the rings and the stationary core. High-energy permanent magnets are arrayed in a circle around the rotating rings, adjacent to the support bearings. The wound motor coils are encapsulated in a heat conducting compound, and set into a recessed ring on the central core, adjacent to the ring magnets, with a constant 5-millimeter gap between the two. Because of the large diameter of the torque motor, only a small amount of power (on the order of 200 kW) is required to maintain the speed of each ring. Hall effect magnetic sensors in the stationary core sense the position and speed of the rings, and feed this information back to a servo control system that keeps the rings in synchronization and at proper speed. Because each coil is independently wound and terminated, the failure of a number of coils can be compensated for in the controlling software.

  In the unlikely event of a complete motor failure (such as might happen in the case of a large scale power loss), calculations show that it would take three days for a ring to despin, thereby providing sufficient time to relocate personnel to the central core and the adjacent ring. Should a ring lose motorization, the friction of the bearings and seals is sufficient to cause a dynamic counterrotation in the body of the Battle School. Automatic control systems are programmed to respond using the attitude control thrusters and the magnetic torque bars to maintain the School’s orbital orientation if such an event should occur. Enough fuel is stored onboard to react against despin forces in the event that both ring motor systems should fail simultaneously.

  The Battle Rooms, as previously described, are cubes with an interior dimension of 75 meters to a side. They are built in three arrays of three Battle Rooms each. Each array has a series of circular corridors connecting, at one level all the Battle Gates, and at a lower level all the Student’s Gates. Secondary corridors coming from the Student’s Gate corridors feed to the Teacher’s Gates on the south face of the cubes. For orientation purposes, the south faces of the Battle Rooms are all located at the radially outermost points. As an example, if the central core were to rotate with the habitation rings, the Teacher’s Gates would be “down.” However, by placing the Battle Rooms in the stationary central core, they experience no gravitational acceleration, and provide the ideal zero-G training environment.

  The spacing and orientation of three Battle Rooms in their “array” allows for large otherwise empty volumes between them. These volumes are taken up by storage spaces for the “Stars” and ancillary support equipment, and by the specialized electro-synthetic gravity generators and focusing apparatus needed to fix the stars in place and permit the Hooks to work in their intended way.

  BATTLE SCHOOL: SHUTTLE CARS (SUBWAY CARS)

  As mentioned previously, the method of moving between a rotating habitation ring and a stationary central core is of utmost importance for the effective functioning of a large space station such as the Battle School. The immense size of the Battle School both creates the problem and provides a means for its solution.

  Given a rotational speed of 2.4 rpm, the outermost point of the habitation rings moves at a tangential speed of 48 m/s (98 mph). Further in, closer to the center, the tangential velocity is proportionally reduced. At the radius of the Game Room Deck (roughly 89 meters from the center axis of the Battle School), the tangential velocity is 22.3 m/s (50 mph).
This Deck is also the first access level to what are called the “shuttle cars” that allow movement between the rotating habitation rings and the stationary central core.

  The shuttle cars are similar in concept to subway cars. They run in de pen -dently of each other, as single car units, on concentric pairs of linear tracks. There are a series of four such tracks, arranged at each interface between the rotating habitation wheel and the fixed core, for eight tracks per wheel, sixteen tracks overall. The innermost (“uppermost”) of these tracks is allocated to service cars that allow equipment and supplies to be moved between fixed and moving elements. The remaining three outer tracks per location are dedicated to personnel. The tracks and the track beds are part of the fixed central core. The shuttle cars run on the tracks, and either remain at zero velocity on the tracks (aligned with marks on the central core), or are brought up to speed and synchronized with the central disk area of the rotating habitation rings.

  For reference and orientation, the sense of gravity in the Battle School is always directed outward. Moving higher in the station brings one closer to the central axis, and results in a reduction of the effective centripetal gravity.

  For the purposes of this illustration, the shuttle car system shall be described as viewed from the Battle Room Access Deck. This deck is located three levels above the Gaming Area, and is therefore aligned with the access corridors to the Battle Gates of the adjacent Battle Rooms. For reference, its radius from center is approximately 72.4 meters.

  The Battle Room Access Deck is a part of the rotating habitation rings. It is accessed by taking an elevator from one of the six available elevator banks in each ring. The Access Deck is above the living quarters, closer in to the central axis of the Battle School. These floors have a more severe upward curvature to them, and the centripetal-gravity effect is lower (very roughly half of normal Earth gravity). The Access Deck is approximately 30 meters (100 feet) wide, interrupted by regular support columns and the elevator banks, and runs the full circumference of the central disk. Facing the long axis of the open deck area (along the circumference), with the floor curving up in front of and behind the viewer, one views walls to the left and right. The upper portions of the walls are clear Plexiglas, and the lower portions are opaque. Automatic, electrically operated doors are set into these walls at regular intervals. A call button is provided to the left and right of each door.

  Looking through the Plexiglas and down, the viewer sees two polished tracks, raised on short supports above the track bed. These are the tracks for the subway car. There is a third track, a wide, flat black ribbon that runs parallel to the polished tracks. This central ribbon carries signal and power to the subway car (transmitted via induction), and houses the coils for the linear electric motor that drives the car along the track. The tracks are moving relative to the viewer at 18 m/s (41 mph).

  On the far side of the tracks, and sharing a common support structure with them, is another wall: Plexiglas on top and opaque below. Automatic doors are set into those far walls at the same intervals as the near wall.

  The far wall, however, is not fixed with relation to the Access Deck. The far wall, as described, is part of the central, stationary core. Because of the constant relative motion between the habitation ring and the stationary core, the far wall also moves with a relative velocity of 18 m/s as compared to the near wall and the Access Deck. Even though the Access Deck is a part of the rotating habitation rings, a viewer standing on the Access Deck will perceive himself (herself) as stationary, with the opposite wall moving past.

  Visible beyond this far wall is another hallway. This is the access corridor for the Gates. Since there are three Battle Rooms along this corridor, these three Battle Gate entrances will pass by a viewer on the Access Deck every twenty-five seconds.

  Every concentric track has a single shuttle car (subway car) mounted to it. The wheels of the car are more like roller-coaster wheels—in that they grab onto the track top and bottom—than they are like actual subway or rail cars. When one of these cars is at rest, it is aligned with a default doorway on the side of the stationary core, and does not move on the track. Being stored on the tracks on the stationary core, there is no centripetal force (artificial gravity) to maintain the car’s position on the tracks or keep it from floating off, hence the wraparound wheels and the captured track.

  When one of the call buttons is pressed on the Access Deck side, it activates a sequence of events to bring a shuttle car to that doorway:

  1) The shot pins holding the shuttle car locked against the platform on the stationary side release.

  2) The shuttle car’s electric linear motor is activated, and the car is accelerated up to the speed of the rotating platform (in this case, 18 m/s). Typical acceleration does not exceed 10 percent G, and it therefore takes approximately twenty seconds for the car to come up to speed.

  3) The shuttle car aligns (synchronizes) its door system with the door system adjacent to the call button.

  4) The shot pins on the moving platform engage the shuttle car. This makes sure that the car remains aligned to the doorway even in the event of power loss. The car, now synchronized with the ring, experiences the same centripetal gravity appropriate to that deck.

  5) The corridor doors and then the shuttle’s doors open, allowing access. Passengers enter (or exit) the car.

  6) Doors close, and the pattern is reversed.

  7) As the car decelerates to match the speed of the stationary central core, it slowly loses the effect of centripetal gravity. Electro-synthetic planar gravity generators built into the floor of the car activate and carefully blend the gravity of the Access Deck to that of the central core (typically kept at 100 percent Earth-normal gravity).

  The shuttle cars, whether full or empty, represent a large rotating eccentric mass which might otherwise cause an imbalance on the fixed central core. The Battle School’s central computer uses the other cars in a given concentric group as moving counterweights to overcome this dynamic imbalance on the core.

  FABRICATION OF THE BATTLE SCHOOL

  Due to the sheer size of the Battle School—28 billion kilograms, or roughly 100,000 times the mass of the original International Space Station—it was by necessity constructed entirely in orbit. The volume of material required mandated that mining and smelting operations be established on the surface of Earth’s moon. Due to the practical difficulties of manufacturing components in a zero-G (or micro-G) environment, much of the manufacturing for the elements of the Battle School and the ships of the International Fleet was also relegated to these lunar facilities. The amount of material required to build not only the Battle School, but the ships of the International Fleet, would have depleted Earth’s resources to the point of worldwide economic collapse. Further economic analyses showed that the cost of launching this material from Earth to orbit was on the order of ten times the cost to set up this lunar mining and manufacturing infrastructure. These lunar manufacturing stations were later employed in the fabrication of the large colony ships, intersystem commercial, corporate, satellites and exploratory vehicles, and similar space-based assets, leading to further amortization of the initial costs.

  The facilities established on Earth’s moon were used to manufacture more than 92 percent of the structural components required for the Battle School, and a large percentage of the infrastructure and incidentals. After the discovery of copper deposits over 300 feet below the surface regolith, fully 97 percent of all ships’ electrical wiring was produced at these plants. The regolith itself was used to create the over 600 miles of optical fiber, used for signal transmission throughout the Battle School, as well as the thousands of miles of optical fiber used in the I.F.’s ships.

  Linear accelerators constructed on the moon were used to throw these prefabricated components to the low-Earth orbit assembly site for the Battle School, where they saw final assembly. Due to the low gravity on the moon—and therefore the low escape velocity—items as large as 50 meters on a s
ide (if properly supported) could be launched from the surface of the moon to low Earth orbit for final assembly.

  FLASH SUITS

  The term “flash suit” describes the collection of gear worn by a student at the Battle School when he or she is to be involved in a training session in one of the Battle Rooms. The flash suit consists of a helmet, a gauntlet-style flash gun, and the suit proper (the garment).

  The flash suits—the garments worn by the students during their training in the Battle Rooms—are composed of interwoven fabric and third generation “Shape Memory Alloy” wires. These Nickel-Titanium-Tungsten wires—derived from a material known as “Nitonol” first developed in the 1960s—are able to remain highly flexible under normal conditions, but stiffen and hold whatever position they were in when a high-frequency voltage is applied across them. This feature enables the flash suits to be “Frozen,” preventing further movement of the student wearing the suit when he suffers a simulated laser “hit.” The suits are divided into zones, so that a student may be partially frozen (legs only, arms only, one arm only, etc.) prior to becoming fully immobilized.

  The suits are padded to protect the students against injury.

  Long-range RFID (Radio Frequency Identification) chips are also woven into the suit material at multiple locations. These chips allow the suits’ position and orientation to be tracked while it is within the confines of the Battle Room, as part of the overall tracking and targeting program used to identify which suit has been hit by which flash gun’s simulated laser burst. These RFID chips are also secreted in other items of clothing, and all may be tracked by sensors scattered around the Battle School itself.

  The insignia of the various armies are permanently imprinted onto the fabric of the suits. These insignia and related decorative treatments wrap fully around the suits on the front, back, and sides. Typical use places the insignia centered on the student’s back, but other approaches have relied upon elaborate designs distributed across the overall suit, gauntlet, and helmet.