Doppler shifts, direction and timing.
Jodrell Bank in Britain tracked Apollo 11 with a smaller dish while its giant Lovell Telescope followed Luna 15. Its records include a Doppler trace showing the lander’s motion and then stillness. [1][2]
In Australia, NASA’s Honeysuckle Creek station near Canberra received the first TV pictures. About eight minutes later NASA switched to the Parkes telescope, which carried most of the moonwalk. The signal went to Sydney and then to Houston for the world broadcast. [3][4][5]
A robot relay would have to sit at the Moon, move like a landing craft, and send live, unscripted conversation with a 1.3-second delay. A machine able to do all that would already have been a Moon landing in all but name.
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