1 Ceres
The undisputed king of the asteroid belt. Ceres is so massive that its own gravity pulled it into a sphere, classifying it as a Dwarf Planet. It contains nearly a third of the total mass of the entire asteroid belt.
Diameter
940 km
Gravity
0.029 g
Water Content
~25% by mass
Escape Velocity
0.51 km/s
The Deep Space Gas Station
Ceres is mostly rock and ice. However, scientists estimate that its mantle contains more fresh water than all of Earth's freshwater reserves combined.
For asteroid miners, water isn't just for drinking—it's rocket fuel. By utilizing solar or nuclear power to undergo electrolysis, miners can split Ceres' ice into Hydrogen and Oxygen (liquid bipropellant). Because Ceres has very low gravity, launching heavy tankers of this fuel to refuel other spacecraft across the solar system is incredibly cheap compared to launching fuel from Earth.
Cryovolcanism
NASA's Dawn spacecraft discovered Ahuna Mons, an enormous ice volcano on Ceres' surface. Instead of erupting molten rock, it erupts a briny mixture of warm water and salts. This active geology suggests an underground ocean of muddy, salty water may still exist, offering tantalizing prospects for astrobiology and easily extractable liquids.