Space Rocket History #142 – Venera 4

“It seemed that the nearby and mysterious planet was resorting to tricks to hide the secrets kept beneath its cover of clouds. As the probe drew nearer, Venus’ gravitational field increased its speed. The Doppler effect altered the wavelength of the signals received on Earth. The radio operators needed to be particularly vigilant so that the information sent from the station consistently landed in the narrow “throat” of the ground-based receivers.”  Boris Chertok