Ss:Water

Volatile Molecule with two hydrogen atoms and one oxygen atom. Required for all known forms of life. NASA currently follows the mantra "follow the water" when trying to find life on other planets. The solar system has a "frost line", where most of the objects have little water closer than it, and objects are composed mostly of frozen water beyond it. Water is thought to come from comets in objects closer in than the frost line.

Water on Worlds

 * Mercury/Water - Mercury/Water
 * Mars/Water - Mars/Water