Aster › Space program › Io
Io
Position on the route: 14/45 · level needed 90 · journey (Mk0 engine) 16.4 h
By the numbers
| Diameter | 3,643 km |
|---|---|
| Gravity | 1.8 m/s² |
| Orbit | 1.77 days |
| Surface | sulfur and silicate lava |
| Volcanoes | 400+ active |
The story
The most volcanic body in the Solar System. The pull of Jupiter, Europa and Ganymede squeezes and relaxes Io every day; this tidal heating throws lava and sulfur up to 300 km high. The colours come from sulfur compounds.
Io sits inside Jupiter’s radiation belt: several hundred rem a day at the surface. So instead of settling the surface, a station in orbit is the answer, one tied to sulfur and geothermal power.
Missions
- Voyager 1 (1979): discovery of the active volcanoes
- Galileo (1995–2003): close flybys
- Juno (2023–24): close Io passes
Colony note
An orbital station only; Mk3 shield. Sulfur is plentiful, geothermal power is large (×3).
☠ Hundreds of rem a day at the surface and constant volcanic eruptions: a landing is lethal. Only a station in orbit can be built.
What probes bring back
- More than 400 active volcanoes: the most volcanic body in the Solar System.
- Jupiter’s tidal heating warms it; the radiation is hundreds of rem a day.