Water Transport Infrastructure
Constructed on a water world, rocky-ice planet, frozen planet, or cryovolcanic planet, this structure transports water to another planet in the system. Does not require an artifact. Having it in place allows you to build:
Water Capture Infrastructure
Constructed on a desert world, this structure receives water and improves the planet to an arid, jungle, tundra, or terran world (depending on temperature). Does not require an artifact.
Cometary Capture Infrastructure
An alternative approach for desert worlds without a nearby water source, captures water-bearing asteroids to hydrate the planet. Does not require an artifact, but is slower and more expensive than standard water transport/capture infrastructure.
Environmental Agency
Removes pollution at a hefty credit cost. Does not require an artifact.
Integration Corps / Subjugation Corps

Two options for removing a decivilized population. The integration corps is costlier but greatly increases immigration while in effect; the subjugation corps is cheaper and faster but only slightly increases immigration. Neither requires an artifact.
Atmospheric Filter
Removes toxic or dense atmospheres. Requires an "atmospheric mineralizer" to complete.
Atmospheric Pump
Adds an atmosphere to a planet, removing the effects of null or thin atmosphere. Requires an "atmospheric sublimator" to complete.
Stellar Mirror
Removes cold or extreme cold. The latter is costlier and takes longer. Requires a "stellar reflector core" to complete.
Stellar Shade
Removes heat or extreme heat. The latter is costlier and takes longer. Requires a "stellar reflector core" to complete.
Stellar Distributor
Removes poor light. Requires a "stellar reflector core" to complete.
Tectonic Engine
Removes tectonic activity or extreme tectonic activity. The latter is costlier and takes longer. Requires a "tectonic attenuator" to complete.
Cyclonic Regulator
Removes extreme weather. Requires a "weather manipulation core" to complete.
Genepurge Project
Unleashes engineered viruses to remove a planet's inimical biosphere. Does not require an artifact to complete.
N-Brane Oscillator
Adjusts the local gravitational field. Requires an "n-brane oscillator core" to have any effect.
Climate Sculpting Project
Can only be built on a terran or water world. Adds "mild climate," further reducing hazard rating. Requires a "terraformer brainprint" to complete.
Lobster Breeding ProgramAdds Volturnian lobster to a water world, but reduces relations with the Sindrian Diktat.