Siege Sphere

Siege Spheres are airborne autonomous weapons created by humanity to fight against the Xegnathi invasion of earth.

Layout and dimensions
Siege Spheres are made up of separate outer, armour and inner spheres. The outer sphere is five kilometers in diameter and three kilometres thick, contains all of a Siege Sphere’s armaments and sensory systems and is heavily armoured. The armour sphere is a solid slab of armour two kilometres in diameter and 1500 metres thick. The inner sphere, 500 meters in diameter, houses the Siege Sphere’s fusion reactor, Countergravitational Repulsion Engine and control computer, remotely connected to the outer sphere via quantum entanglement link.

Power supply
Siege Spheres possess an experimental “quantum power farm” within their inner sphere which supplies all their power needs and can operate almost indefinitely. As a backup the inner and outer spheres have large numbers of redundant batteries within them; a single battery can power the entire Siege Sphere for around an hour.

Direct fire
Particle cannons: A particle accelerator runs around the equator of the outer sphere, connected to 100 evenly-spaced coilguns. The accelerator is used to synthesize large quantities of exotic heavy particles which are wrapped in esoteric pseudo-magnetic containment fields and projected from the coilguns at half the speed of light. The particles carry very little kinetic energy due to their low mass and exotic properties but when the containment field fails they decay on contact with normal matter, releasing exotic energies which seem to mutually erase normal matter from existence in defiance of therodynamics. A shot from a Siege Sphere particle cannon carrying the maximum possible mass of particles (three tonnes) will erase all matter within a thirty-metre radius of the point of containment field failure regardless of its composition. The containment field can be adjusted to fail after a certain amount of time (between one second and one hour) has elapsed since its manifestation or to fail immediately on contact or close proximity (between one centimetre and twenty metres) with particular substances or states of matter.

Omnichromatic lasers: A Siege Sphere has forty advanced focusing lenses spread evenly around its outer sphere, used to project coherent beams of electromagnetic radiation spanning the entire spectrum of optical frequencies – in short, lasers that shoot every wavelength of visible light at once. Thanks to the ability to project an esoteric “focus tube” up to 500 kilometers away from the weapon, the lasers can maintain full coherency and power with no atmospheric diffraction or bleed-off up to that distance. They have a maximum output of 42 petwatts and can fire in 0.1 second bursts or continuous beams for an indefinite length of time thanks to advanced cooling systems.

Napalm lasers: The predecessors of Siege Spheres and other weapons of their generation were equipped with plasmatic cannons, which project globs of high-temperature ionised gas at extreme velocities. These weapons make use of a laser to clear a path for the plasma and the napalm laser is a further evolution by which the laser itself is powerful enough to deliver some damage for a two-stage attack. Thanks to the ability to project an esoteric “focus tube” up to 500 kilometers away from the weapon, the lasers can maintain full coherency and power with no atmospheric diffraction or bleed-off up to that distance. The laser part of the weapon transfers 50 petajoules of energy and the plasma, travelling at 500 kilometers per second, has kinetic energy of 150 petajoules. Siege Spheres mount sixteen of these weapons spaced evenly around the outer sphere.

Railguns: twenty-eight railguns spaced around the outer sphere. Each round, travelling at just shy of 10 kilometres per second, uses a combination of a thirty-kiloton thermonuclear shaped charge, a duryllium drill tip spinning extremely fast and its 80 petajoules of kinetic energy to penetrate an armoured target before detonating its explosive payload, equivalent to fifty kilotons of TNT.

Positron lasers: The endpoint in development of electrolaser technology, a positron laser uses a coherent beam of electromagnetic radiation to form an electrically conductive plasma channel. A fraction of a second later, a powerful electric current is sent down this plasma channel and delivered to the target; the current is then used to transfer an esoteric effect which inverts the particulate charge of electrons, creating positrons which then annihilate with nearby electrons. In short, it’s an antimatter lightning gun. Positron lasers are incredibly destructive, creating powerful explosions through the atmosphere all the way to the target and causing armour not made of exotic materials to explode on contact. The weapons have a maximum range of 420 kilometers.

Indirect fire
Siege Spheres carry no missiles, artillery or other ballistic indirect-fire weapons. Instead they are linked to a network of satellites and siege stations in low earth orbit which provide fire support for human forces.

Armour
A Siege Sphere’s outer and armour spheres are constructed of advanced exotic armour materials such as tetraneutronium and duryllium. The armour sphere is made entirely of over a kilometre of solid armour and can be rotated in the event that the armour is compromised so that less damaged areas can face more intense enemy fire.

Tetraneutronium is humanity’s most advanced armour material, consisting of an allotrope of neutronium which is composed of groups of four neutrons bound together in a manner which violates conventional physics. Use of a variation on the technology used in Zoraki Reinforcement Fields the entire macroscopic structure of a layer of armour is bound together in this physics-defying manner, making it extremely hard to break apart via the use of conventional weapons based in any branch of ordinary physics. Without exotic effects such as weaponised temporal mechanics, strong-force nullification or the most advanced gravity-based weapons in play a single millimetre of tetraneutronium armour offers the same practical protection as five thousand metres of conventional steel. As it is extremely expensive and time-consuming to synthesize the substance a Siege Sphere has only five layers of tetraneutronium armour a tenth of a millimetre thick spaced evenly through its amour sphere, and another layer a millimetre thick around the inner sphere.

Duryllium is a compound of carbon, depleted uranium, xenon and exotic heavy particles; a single millimetre of it offers the same protection as one hundred meters of conventional steel and time-dilated experiments have shown it to be functionally immune to corrosion and wear in any practical timeframes short of those involved in sub-luminal extra-galactic space travel. All armour, moving mechanical parts and other components that don’t require specific material construction in the outer sphere are made of duryllium, with its resilience doubled by the liberal application of Zoraki Reinforcement Fields. The armour sphere is four solid layers of duryllium 375 metres thick, separated only by the three of the five layers of tetraneutronium.

Defensive armament
Point-defence lasers: [Technical information coming soon] Although considered the epitome of human point-defence technology the system still struggles to handle massed Xegnathi artillery fire from thousands of MLRS platforms and automatic mortars in conjunction with swarming aircraft.

CIWS turrets: Multi-barrelled Gatling railguns dot the surface of the outer sphere, clustered around the weapons. Firing steel-coated duryllium rounds the size of a sand grain at 1 kilometre per second they intercept and destroy missiles and shells which penetrate the laser defence grid.

Barriers
Similar to the “force fields” seen in many works of science fiction, a Siege Sphere’s barriers act as a remotely-projected imitation of solid armour, impeding the passage of objects in the same way as armour. The barrier projectors are programmed to open a form-fitting hole in the barrier when objects touch it on one side but not on the other, allowing the Siege Sphere to shoot out of its barriers while they impede enemy attacks.

There are three layers of barriers, all projected fifty meters away from the surface of the outer sphere. The central layer is a single large barrier which encompasses the entire sphere, and spins at high speed to slap aside kinetic weapons rather than simply take them straight-on and prevent continuous-beam weapons from firing on one point on the barrier for longer than a fraction of a second. The outer and inner layers are a set of multiple curved “plates” forming a sphere, which can be moved to any point around the area of projection to allow increased shielding in particular areas. One layer of a Siege Sphere’s barriers require at least 50 terajoules of energy focused on a given spot to penetrate.

Mobility
Siege Spheres use the Countergravitational Repulsion Engine, a precursor to the Gravitational Projection System (Mass not Required) used for gravitational propulsion and artificial gravity in spaceships, to levitate off the ground. Unlike GPSMR which can push or pull in the absence of existing gravity a CRE can only push against existing gravity wells, confining Siege Spheres to atmospheric or orbital operations rather than deep space. Using its CRE for motion in any direction a Siege Sphere can travel at a maximum of 55 kilometres per hour in sea-level atmospheric conditions and marginally faster at higher altitudes.

Command and control
All Siege Spheres are controlled by an artificial intelligence housed in an advanced computer brain 10 metres in diameter inside the inner sphere. The AI has conscious reaction times of roughly one millisecond (versus 150-200 milliseconds depending on stimulus for an average human) and can multitask efficiently enough to control all of the siege sphere’s functions at once. The AI is capable of extensive electronic and psychotronic warfare but this isn’t really used because the exotic nature of Xegnathi computers and communications cannot be successfully interacted with by equivalent human technology without extensive prior preparation.