Colonization of the outer Solar System Colonization of the outer Solar System Many parts of the outer Solar System have been considered for possible future colonization. Most of the larger moons of the outer planets contain water ice, liquid water, and organic compounds that might be useful for sustaining human life. Colonies in the outer Solar System could also serve as centers for long-term investigation of the planet and the other moons. In particular, robotic devices could be controlled by humans without the very long time delays incurred in communicating with Earth. There have also been proposals to place robotic aerostats in the upper atmospheres of
Solid Solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). In solids molecules are closely packed. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other, either in a regular geometric lattice (crystalline solids, which include metals and ordinary ice) or irregularly (an amorphous solid