HARBOURS, 

ASTEROID DOCKS

           The rapidly expanding Federation fleet required a corresponding expansion of servicing facilities, though a wide range of existing surface facilities could be expanded, more ships which were not designed for trans-atmospheric flight were quickly running out of servicing stations.

            The solution was to construct specialized harbour ports that would take a great deal of strain off the existing infrastructure while also reducing traffic in key areas of busy systems. These new stations were going to be based on asteroid settlements, a niche that had already begun to be exploited for certain good manufacture. The alternative of creating space stations would require the shipping of prefabricated components to a destination orbit, though this would allow for any location, and tailor built designs, but the structural components would have to be fabricated and transported to the site. The opted alternative was to use asteroid bases which provided all the on-site material while creating an internal environment which could accommodated the biggest ships in air dock (that is to place the ships in atmosphere) without having to transit a planets atmosphere, the finished structures would be simpler to build, quicker as a result and provide much better services.

            Nearly all star systems have a suitable numbers of orbiting rocks that can be turned into harbours, asteroids of 10km or greater are usually chosen, simply because these larger bodies offer more raw material and room for expansion, and also the creation of large internal habitable caverns, which would provide pleasant environment to ship handling personnel as well as ship crews. Apart from the chosen type of rock, the next divergence is the harbour design.

            The non-rotating type of harbour relies on arresting the asteroids rotation, so that the same side always faces the sun, this greatly simplifies the docking procedure for the craft as it does not have to worry about match a rotation and vector to a rotating surface. The asteroids rotation is usually arrested by placing automated fusion thrusters on the surface, they first send lines deep into the rock, anchoring itself and the surrounding rock, next maneuverable exhaust jets decelerate the rotation by firing into its rotational direction. When the asteroid has been decelerated large solar fins are installed which maintain the same face towards the sun, while simultaneously providing large heat exchange surfaces which help regulate the temperature of the asteroids interior.

            The dock parts are simply built on the surface of the asteroid, or large open mouthed caverns open up into a hollowed interior (preferred type this provides a rocky armour shell). The docking bays themselves are of standardized design, and a Materials Processing Machine (MPM) can consume the excavated rubble and convert into these components for the harbour.

The second stage is to equip the asteroid with a habitat. The habitat provides the needed natural environment beyond the industrial structure of the docks, on a non-rotating asteroid artificial gravity has to be generated to maintain a sense of gravity. This is one of key differences in design, rotating asteroid can produce hollow cylindrical rotating habitats that when rotated generate an apparent gravity.

The most typical design is to create a large ‘canyon’ on the sun facing side, the floor of the canyon has a network of artificial gravity generators, that provide a terrestrial strength field to the top of the canyon (it is important for the artificial field to end there as otherwise hapless starships way encounter an unexpected gravity well). The canyon is roofed over with alternating layers of laminate diamond and radiation filter, further filters can be made to produce a ‘natural’ sky, as the black expanse of space with a sun in the middle of it does look rather odd. The internal space is then pressurized and biota and organic materials introduced to complete the environment.

Only one further problem remains, as the asteroid maintains one face to the sun, a cavern can either chose to have day or night, this arrangement is unsatisfactory. Day side facing caverns build controllable filter to render the ceiling opaque and therefore create an artificial night, in some more elaborate cases an artificial moon is pushed by microwave laser to eclipse the sun. This produces a more normal effect, and if the sun is eclipsed well this itself can be quite a spectacle, the system does have penalty in being quite complicated, but a movable sail at the Lagrange point between the harbour and the sun and controlled in position by the sun’s light pressure and reaction by microwave laser works quite well. Night side settlements can create artificial days by using large reflecting mirrors, these often form an orbital band around the rock, day can extinguished by controlling the angle of these mirrors. On the whole ‘Dayside’ are by far the more common type.

The second mainstream harbour type is the rotating harbour, in essence these are easier to construct but they provide a harder docking site to large craft, for this reason these type of ports are far less numerous than non-rotating harbours.

The process of modifying an asteroid is essentially the same, except any actions to change or regularize the asteroid’s rotations finish with a body that retains a rotation about one axis.

Docking yards are provided in much the same, usually internal sheltered by a large rocky shield, this shield is useful as it cuts down on radiation and thermal differences, also it shades the docks allowing better optical navigation, and of course provides a great deal of armour from a military point of view.

Rotating habitats have a simpler design, in essence a huge cylinder is excavated whose axis matches the asteroids rotational axis. A floor is then generated by the centrifugal forces, this acts as maintenance free artificial gravity. However lighting remains a problem, some use giant ‘skylights’ which are windowed shafts to the surface, many of these are needed at different sections of the cylinder, but the lighting effect generated is artificial and peculiar, also as the ‘ceiling’ is also the ‘floor’ these skylights consume large amounts of the habitats surface. A better method is create a giant circular window at the end of the cylinder, but rather than pointing this at the sun, which would mean all the light would come in horizontal (which greatly effects the natural form of the pant life), the light is reflected off a giant conic mirror which reflects the light perpendicular to the ground, this produces a much more natural effect. Cylinder habitats are quite impressive as ‘sky’ and ‘ground’ lose meaning, some find the effects gives them insurmountable vertigo, though most acclimatize easily enough. Cylinder habitats are also viewed as ‘hardier’ and less prone to damage, though with roofing materials in the canyon type of habitat this statement is questionable.

Some of the smaller, and usually younger harbours give up on natural skies altogether and furnish their rocky caverns with artificial lighting. This is certainly preferred if the harbour is meant to be a stealthed military asset, as no surface features could distinguish it from being natural.