Ceres
Position on the route: 9/45 · level needed 55 · journey (Mk0 engine) 10.2 h
By the numbers
| Distance from Sun | 414 million km (2.77 AU) |
|---|---|
| Diameter | 940 km |
| Gravity | 0.28 m/s² (0.03 g) |
| Day | 9 h |
| Year | 4.6 years |
| Temperature | −105 °C mean |
| Class | dwarf planet, largest in the belt |
The story
A third of the asteroid belt’s mass is Ceres alone. Called a planet when found in 1801, then an asteroid, a dwarf planet since 2006. The Dawn spacecraft orbited it from 2015 to 2018 and showed the bright spots in Occator crater to be sodium carbonate: brine that seeped up and evaporated.
Remnants of a briny liquid layer may lie under the crust; a quarter of the body is water ice. That makes it a fuelling station between the inner system and the outer planets: water from ice, oxygen and hydrogen from water.
Gravity is so low a person cannot jump to orbit, but escape velocity is only 1,850 km/h; leaving is very cheap. The other large bodies of the belt are Vesta (Dawn 2011–12), Pallas and Hygiea.
Missions
- Dawn (2015–2018): the only orbital mission, after Vesta
Colony note
An ice-rich, low-gravity waystation. The hard part: little sunlight and the health effects of almost no gravity.
What probes bring back
- The bright spots in Occator are sodium carbonate: brine seeped to the surface.
- 25 % of the body is water ice; briny liquid may remain under the crust.
- Ammoniated clays: it may have formed in the outer system.