Aster › Space program › K2-18 b
K2-18 b
Position on the route: 41/45 · level needed 2200 · journey (Mk0 engine) 373.2 h
By the numbers
| Distance | ≈ 124 light-years |
|---|---|
| Radius | ≈ 2.6 Earths |
| Mass | ≈ 8.6 Earths |
| Year | 33 days |
The story
A world between a small Neptune and Earth, the proposed ‘Hycean’ (hydrogen plus ocean) class. In 2019 Hubble found hints of water vapour; in 2023 JWST measured methane and carbon dioxide; some teams debated a dimethyl sulfide signal (on Earth made only by living things), which was not widely accepted.
The claims of evidence for life are not confirmed and the scientific debate goes on. Even in the game this is marked as a target where ‘real science is contested’.
Missions
- Hubble (2019): hints of water vapour
- JWST (2023, 2025): methane, CO₂ and a possible DMS
Colony note
A liquid ocean under a hydrogen atmosphere: suited to orbital or floating settlements, not to a surface.
What probes bring back
- About 124 light-years; in 2023 JWST found methane and CO₂ in its air; some teams debate a dimethyl-sulfide signal (a biosignature).
- The ‘hycean’ class: a liquid ocean under a hydrogen-rich atmosphere.