The first glimpses of the surface using radar from Earth

The surface of Venus has long been hidden from human eyes by the thick veil of clouds, leading, as we have seen, to all kinds of speculation about what lies beneath. However, radar can be bounced from the surface and the recorded echoes synthesised into a picture, and today most of our detailed knowledge and mapping of the surface has been obtained in this way. To get good resolution, and to cover the polar regions, the radar equipment needs to be on a spacecraft orbiting Venus.

However, before the first mission to carry radar flew to Venus in 1978, remarkable progress had been made in obtaining pictures of the surface using the same technique all the way from the Earth. This requires a very large dish antenna to transmit and receive the pulses, and those at Goldstone in California and at Arecibo in Puerto Rico were the first to be pressed into service.