Page "Venera" Paragraph 6

Among the other results, probes of the series became the first man-made devices to enter the atmosphere of another planet ( Venera 4 on October 18, 1967 ), to make a soft landing on another planet ( Venera 7 on December 15, 1970 ), to return images from the planetary surface ( Venera 9 on June 8, 1975 ), and to perform high-resolution radar mapping studies of Venus ( Venera 15 on June 2, 1983 ).

So, the entire series could be considered highly successful.

Unfortunately the surface conditions on Venus are extreme, which meant that the probes only survived on the surface for a duration of 23 minutes ( initial probes ) up to about two hours ( final probes ).