Venus

The powers of Earth have started terraforming of Venus. However, unlike Mars, it will take humanity a very long time to complete the project.

Phase 1 - Preparation & Cooling (0-60 years)

• Build vast orbital mirrors to block sunlight and cool Venus.
  Atmosphere slowly cools while remaining dense.

Phase 2 - The Great Flood (≈60-90 years)

• At 31°C, CO₂ liquefies → begins raining down for ~30 years.
• Global cooling accelerates.
• Pressure drops; Venus becomes covered in liquid CO₂ oceans.

Phase 3 - The Big Freeze (≈90-150 years)

• Surface cools to −81°C.
• CO₂ oceans freeze into rock-hard ice and glaciers.
• Atmosphere left with nitrogen at ~3× Earth pressure.

Phase 4 - Atmosphere Management (150-500+ years)

• Prevent frozen CO₂ from re-vapourising:
• Options: insulate, bury, or eject into orbit with mass drivers.
• Import water from Europa (via tethers, mass drivers).
• Balance nitrogen levels by exporting excess gas into space.
• Venus becomes a world of shallow frozen oceans, continents, and islands.

Phase 5 - Light & Heat Regulation (Centuries Later)

• New orbital mirrors provide controlled sunlight and artificial day-night cycles.
• Begin thawing water oceans.

Phase 6 - Biosphere Seeding (1,000-3,000+ years)

• Introduce cyanobacteria → oxygen production and nitrogen fixation.
• Fertilisation of oceans.
• Grind surface rock into soil for nitrogen-fixing plants.Spread forests and
• vegetation.
• Release controlled amounts of CO₂ for plant growth.
• Possibly engineer new life adapted for Venus.

Phase 7 - Human Habitation (Several Thousand Years)

• Atmosphere becomes breathable for humans.
• Only oxygen masks needed before full conversion.
• Ecosystems flourish with animals and plants.
• Cities and societies develop on a lush, Earth-like Venus.

Summary

• Hundreds of years → Freeze Venus and import water.
• Thousands of years → Create oxygenated, habitable biosphere.
• End state: A second Earth capable of sustaining billions of humans.

Source: How To Terraform Venus (Quickly)