Vacoy biology and ecology.
     Most would argue that exobiology is a useful tool for proving evolution. The catch is that I'm a creationist and I can do exobiology just fine thank you. Evolution puts some constraints on biology. The information building function of random mutation is disputed but even if it did work, billions of years are required. Many solar systems just are not that old according to evolutionary cosmology  assumptions. If we find life 'out there' it will probably be in the wrong place precisely because such anomalies undermine evolutionary theory. God does not tolerate falsehood for long.
An asteroid biosphere: the Vacoy.
    The vacoy are both plant and machine. Biologically refined and deposited silicon, plastic and conductive materials. Both photosynthetic and photoelectric energy cycles exist in combination. Some take root on asteroids feeding on the materials there. Others are mobile traders. The vacoy trade waste products with each other thus transporting elements from areas of space, asteroids, rich in a resource to areas poor in it. No single asteroid will have all the needed elements.
   The vacoy play host to many creatures that wander from ship to ship. These creatures are called 'envoy'; most are soft skinned animal like in form but they are well adapted to varying atmospheric chemistry and zero gravity. Many hibernate or become plant like symbionts on long journeys. These include symbionts that aid nutrient/waste transport, Some carry seeds and pollen or spare hull cells. Parasites and predators hunt them all keeping populations in check. Some vacoy speed their growth by going through a larval stage living in the parent or other vacoy as an envoy. These vacoy/Envoy repopulate dead vacoy and recycle those hulls that are beyond hope.
    The most basic vacoy hull seed is a microkite a few millimetres across. These circulate like envoy within the vacoy fleet but some microkites can survive in hard vacuum as free flying solar sails. Free flying microkite are highly charged and attract dust which they can absorb and use to grow. When free flying microkites meet they join edge to edge forming a structure that eventually folds into a sphere or other volume that can maximise allowable gas volume and surface area while minimising mass.  There are vacoy that sweep up these microkites and absorb them as "food". Others spew them out as living reaction mass. Some do both.
     Microkites that ride the airflows inside a vacoy, or move with the envoy from bioship to bioship, put out fine feelers of polymer. If these find a receptive section of the inner plastic portion of hull they bond into the plastic and grow adding another silicon scale to the mosaic of the hull. Since these scale can grow to up to 10 meters; the new scales added allow these living ships to take a range of complex shapes. Microkites can also form internal walls and structural ridges inside a bioship adding strength as the Hull grows in size.  Stress on the hulls tend to attract these microkites to those points that need them most.
Not all mature bioships make and release microkites. Some bud off nearly mature young; others produce young as Envoy.
  The vacoy do not fly around the solar system using rocketry. The fuel demands are far too much. Some simply orbit like asteroids. The main means of propulsion is electromagnetic. They generate large magnetic fields that both shield them from charged particles and allow them to ride the solar winds. Others put out weak plasmas that form a sail that react with the solar wind to produce a few newtons of force per ton of ship. Smaller vacoy motor about within the fields of the larger ones using more complex electromagnetic fields and charged wires up to a mile long. When fields interact the vacoy are often drawn together pole to pole. Various field manipulation coils embedded in their shells fender and control these collisions.
    When docked the vacoy trade air, water drops, envoy, toxins, etc. One vacoys poison may be the others medicine. Complex reactions follow. The chemistry of the vacoy pair or cluster equalises over a few hours or days. The hatches are mechanically similar to those built by humanity. All vacoy hull seed cells have small pin hole hatches. Other  hatches are standardised genetically to a dozen fixed sizes. From the pin hole to others as large 3 meters across. A hatch that is not the correct size rejects docking or is rejected by others. Hatches do not grow in size over time; each sized hatch seems to be a separate microkite or envoy species. When the vacoy hull reaches the right size it somehow triggers a hatch to nest in its surface and grow to its mature size promptly. Smaller unused hatches seal over in time once larger hatches mature but most vacoy have some hatches of each of the sizes. Some hatches have pumps and fans to speed air flow. Some vacoy dock permanently becoming a larger composite hull composed of globes and cylinders.
    When the atmospheres match then the hatches close and the vacoy use micro scale electrical plants, solar electric systems and chemical nanobatteries to dump power into the superconductor field coils. The fields are reversed in one vacoy repelling the other. Fields of the opposite pole are diminished or internalised within their volume. The vacoy become a temporary monopole riding the others fields away. Once clear by many kilometres the vacoy reverts to being a normal dipole field source.
vacoy summary
     Some vacoy have legs. These are the creepy crawlies, cable runners and Vacuum Cattle of the Vacoy Ecology. They play a great part in the vacoy ecosystem. They run about keeping the hulls clean. They use much less energy ,running about the scaffolding of a flock, trading chemicals. Some can drain a dead vacoy of all the air inside, leaving the shell to be chewed up by others. Thus they recycle dead hulls eating silicon and the plastics; nothing is wasted. On asteroids where the domes are young and their roots donít yet interlink the legged creatures are vital as couriers.
    Vacoy are barely classifiable as a single organism. While there is a single body its cells do not share a single genome. Like a reef or forest hundreds of species make up the whole. The mind of a vacoy is often an envoy symbiont or group of symbiont acting and reacting locally to control the nearest field coil. They are not very intelligent. Their power and wisdom exists in the simple fact that their actions are very limited. Any symbiont that acts against the whole is simply overwhelmed and ignored. Natural selection favours pattens of instinct and responses that favour the survival of the whole vacoy. Many sing to each other in a complex manner. The vacoy ring with mating calls, docking calls, warning cries and a cry that says "bioship off the port bow".
    Gas pressures are kept in equilibrium by reacting chemicals together to make storage solids. Often these reactions produce solid chemicals that double as energy storage systems. Carbohydrates, hydrides, solid peroxides, organically refined metals, nitrates, and carbonates are all used. Some vacoy shade part of their hull to create a cold volume that holds complex ices that of water and:  methane; CO2; peroxides; or ammonia. In many cases when the chemicals in these solids are needed they are reacted together and the energy is used to make other solids so that the gas pressure does not change while the gas mix is drastically changed.
    Vacoy are not radiation resistant but they are hard to kill. Solar flares take their toll killing many individual cells and some symbiont's. Like a forest fire on earth this is often a disaster that allows new growth. The vacoys silicon, plastic and super conductors are all dead tissue immune to radiation. The cells of the average vacoy or envoy are filled with enzymes that undo genetic damage quickly. Complex systems of genetic checking, backup gene copies, mutation hunting proteins and in some cases whole backup nuclei are used in the vital hull forming, hatch forming and chemical control cell lines/ species.
    The vacoys magnetic shielding also helps deal with radiation. However the fields also focus the high energy particle to their magnetic poles. To avoid fatal results Larger vacoy rarely travel alone. Using super strong cables they form rings, toroids and hollow scaffolds  hundreds of meters across. Their magnetic fields combine and  cables are charged to bend the combined fields poles clear of any given vacoys hull. The deadly flux passes through the hollow axis of the ďflockĒ.
    Another trick used by some vacoy is to structure themselves into a flat sheet with a set of cables projecting away from this surface in long loops. Current in these cables shift the field axis clear of the living systems. With solenoids above and below the plane of the hull these balance the forces of the solar wind while keeping the charged particle flux clear of any living cell.
   Envoy and smaller vacoy survive by migrating to the dark side of a larger vacoy putting meters of silicon, water, atmosphere, etc between them and the solar flare. On asteroids vacoy of all sizes migrate to the dark side to hide. Because asteroids often rotate slowly, ~6 hour days, these vacoy must move to survive. The dark side is often fatally cold so much of a vacoys reserve energy must be used to stay warm. The area just behind the dusk line (evening terminator) is safest because the rock is still warm; most smaller creepy crawly vacoy hide there.
   Dome vacoy can not move. These are often mobile vacoy that have nested on an asteroid. Domes inter link themselves via hollow roots. This allows gases to be shared, envoy to move freely and heat to be distributed to the dark side of the asteroid. Domes send roots deep into the rock, ices or metal ores of the asteroid to harvest materials. Radiation is also a threat but less so. Domes cache microkites, progenerator and mobile repair cells in their roots well shielded from both radiation or cold.
     It might be asked how the vacoy and envoy know that flares are due soon? They respond to distant patterns in solar activity that precede a flare by hours or days. Only a few specialist vacoy organisms gaze at the sun with optical systems every bit as sophisticated as the best humanity can craft. These sun watchers are fed well and are very well protected. Many are envoy as juveniles and embed in the hull when mature. These watchers sound the alarm when a flare is pending. The hulls and halls of the vacoy fleet chime loudly with their warning cries. Other vacoy and envoy systems relay the call by song and laser to all to take shelter.
    The harsh vacuum of space may be a challenge but it is not impossible to envisage a biosphere that feeds on nothing but sunlight and the bare rock, siliconís, metals of the asteroid belt. Would we even know they were out there? We can only see the lighter coloured [brighter] asteroids. We only have a fraction of them tracked, numbered or named. Something moving about under its own power would be deemed an error. Asteroids only orbit they donít migrate. We are not looking for life in hard vacuum. In what part of the spectrum would they reflect light? What is the colour of silicon clad chlorophyll? Retinol? Photoelectric bio-silicates? Greenhouses seen from the air are rarely green. For every material man has used in space there is a biological analog. 
Should we be looking?
Wesley Bruce
See also:
Bioballoons ecology and biology.