Zero Gravity--No way!

Frequently you will hear news commentators and others use the phrase zero gravity when covering space events. There is no such thing as zero gravity. Everything from elephants to rocks to spacecraft have mass and are attracted to everything else that has mass by a gravitational force. Isaac Newton showed that this force is proportional to the masses of the two objects and decreases by a factor of the square of the distance between them. The mass of all material bodies, whether on Earth or in space results in inertia. It thus takes a force to start and object moving or to change its motion.

What a spacecraft or its inhabitants do not have in space is weight. For weight comes from resisting the pull of gravity. You have weight because you are being pulled against the floor, and the floor keeps you from falling any further. If you bungee jump off a bridge, you will be weightless briefly because you are in free fall. The force of gravity is constantly acting on anything in orbit, be it the moon, the space shuttle or other satellite. The orbiting satellite stays there because the downward force of gravity pulling the satellite toward the Earth counterbalances the forward momentum of the satellite given to it by the launch rocket. The satellite's momentum continues even after the rocket stops thrusting and falls away. Without the gravitational pull, the satellite would fly off into space. Without friction or drag in airless space, an object can remain in orbit nearly indefinitely. The Moon has been orbiting the Earth for billions of years with nothing pushing it.