DEFINING SPACE : The meaning here is the difference in area occupied. For example, a room in a house as it differs from another room and the house itself. This is the definition of the FIVE SPACES.
1.ATMOSPHERIC SPACE. Any planet as defined by the three gases upon which we depend on Earth. Earth, Air, Fire, Water. (Think seas, as separate spaces within the atmosphere.)
2.OUTER SPACE: Our current obsession. Containing planets, stars, debris, particles.
MORE COST EFFECTIVE ? Practice makes perfect.