High gain antenna
In order to communicate with the Earth, Surveyor uses a 1.5-meter (59-inch) diameter high-gain antenna dish that sits at the end of a 2.0 meter (6.6 foot) long boom attached to the propulsion module. Two rotating joints, called gimbals, hold the antenna to the boom. The gimbals allow the antenna to automatically track and point at the Earth while the science instruments observe Mars.
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(From NASA)