2nd April 1963 Launch of Luna 4
It is believed to have been a Lunar Lander mission but a course correction seems to have failed and the probe flew past the Moon at a range of 8,500 km on 6th April 1963
On This Day (2)
2nd April 1964 Launch of Zond 1
Officially described as an "automatic station" for the purpose of "further developing a space system for distant interplanetary flights" Many observers believed that Zond 1 was a Venus fly or even designed to impact Venus, but after two course corrections contact was lost in mid May 1964.
On This Day (3)
2nd April 1998 Launch of TRACE
TRACE ( Transition Region And Coronal Explorer) was a NASA space telescope designed to study the Sun in UV and EUV it was operational until 2010.
How TRACE viewed the Sun