The machines, equipment, hardware, and even people that are carried into space atop rockets or inside space shuttles are often called payloads. The term originated in World War I (1914-1918) during efforts to determine the amount of cargoes and people that could be carried by land tanks. The term is also often applied to the amount of useful weight that can be lifted by airplanes and inside trucks. Without a useful amount of payload—the "pay" carrying load—any transportation system would be of minimum value since the objective of a transport is to carry cargoes from destination to destination. This is true whether the transport in question is a rocket or a car and the payload consists of satellites or groceries. Payloads can consist of nearly anything that researchers, government, or industry seek to place into space. Satellites, robotic probes, or...