These are plants for culturing and dispersing massive quantities of the transgenic bacteria that New Terraformers use to raise oxygen levels, or raise or lower levels of carbon dioxide. They are normally housed in large, slow sea vessels or aerostats.
Comets are a vital tool in terraforming. Comet tugs are small ships equipped with powerful tractor beams and sub-light drives. In fleets, they steer and accelerate comets toward their destinations. They may also be used to give a comet a (relatively) soft touchdown, if that is desired.
Comet Mining Stations:
Different comets have different uses. "Wet" comets, rich in water ice, are for irrigation. "Dry" comets, rich in carbon dioxide, are for warming. Mining stations, set up beside a comet, strip out undesirable veins of material, tailoring the comet to its task. They also break large comets up into smaller ones, to make them more managable to the tugs.
Terraformers sometimes need to stimulate vulcanism, produce several small earthquakes rather than one big one, sculpt canyons, chisel tectonic plates, or tailor planetary magnetic fields. For this, they use small hyperdrive drones, set to come out of hyperdrive at carefully specified points inside the planet, producing enormous subterranean explosions.
Until an entire planet's atmosphere can be rendered breathable, terraformers may need to maintain breathable pockets. Older technologies use domes or subterranean chambers, but psi-tech terraformers use directed Brownian motion to maintain artificial concentrations of oxygen or high pressure.
To supply needed biota, terraformers run ranches and farms to raise the desired plants and animals.
To cool a planet quickly:
Kick up dust with asteroid or comet strikes, or shallow tectonic missiles, or by missile-stimulated vulcanism. (However, vulcanism may introduce unwanted greenhouse gases.)
To cool a planet permanently:
Remove carbon dioxide by introducing carbon-fixing bacteria or plants.
To heat a planet:
Add carbon dioxide from dry comets, or by burning or metabolizing native carbon deposits, or by stimulating vulcanism. (However, vulcanism may introduce unwanted cooling dust cover in the short term.)
To aerate a planet:
Add oxygen by cracking native water or cometary ices, using oxygenating plants or bacteria.
To aerate a locality:
Dig a very deep canyon or crater, using geo-tectonic missiles, introduce cometary gases, then shield with diffusion barriers if necessary.
To irrigate a planet or a locality:
Add water from wet comets, or use geo-tectonic missiles to carve canals connecting to an ocean or an ice cap. (Using an ice cap may entail heating the planet.)