How does harvesting water ice from asteroids benefit deep-space missions?

Water can be split into hydrogen and oxygen for rocket propellant, reducing fuel hauling from Earth.

Water ice retained within certain asteroids, especially those found in the outer asteroid belt and some C-type NEOs, represents a resource of immense practical value for space exploration. Water itself is useful for consumption, but its greater value lies in its potential for producing rocket propellant. Through the process of electrolysis, water can be efficiently split into its constituent elements: hydrogen and oxygen. These elements are the most powerful components used in modern chemical rocket fuels. If space missions can refuel by accessing and processing water from asteroids encountered along their path, the need to haul massive, heavy tanks of propellant from Earth’s deep gravity well is drastically reduced, leading to a significant decrease in mission cost and complexity for exploring Mars and regions beyond.