Pioneer venus 1 & 2
Pioneer venus 1 was the first spacecraft to map the surface of venus. Pioneer venus 2's probes found that below a haze layer at 30km the vensian atmospere appears to be relatively clear.
Dates of discoveries
The pioneer venus 1 and the pioneer venus 2 launched to venus in 1978.
There was rockets , probes and radio transmitters.
Now we all know more about pioneer venus 1 and 2.