[what is a satellite] [orbiting machines] [satellite elements]

		What is a satellite anyway? A satellite is any object that orbits or revolves around another object. For example, the Moon is a satellite of Earth, and Earth is a satellite of the Sun.

Orbiting Machines In this exhibit we'll look at the man-made satellites that orbit Earth and the Sun -- highly specialized tools that do thousands of tasks every day. Each of these satellites has many parts, but two parts common to all satellites are called the payload and the bus.

Satellite Elements The payload is all the equipment a satellite needs to do its job. This can include antennas, cameras, radar, and electronics. The payload is different for every satellite. For example, the payload for a weather satellite includes cameras to take pictures of cloud formations, while the payload for a communications satellite includes large antennas to transmit TV or telephone signals to Earth. The bus is the part of the satellite that carries the payload and all its equipment into space. It holds all the satellite's parts together and provides electrical power,computers, and propulsion to the spacecraft. The bus also contains equipment that allows the satellite to communicate with Earth. Check out Satellite Anatomy for more information about what makes a satellite work.