Some sources claim that in the 1980s USSR already developed instruments that were capable of operating at surface environment of Venus as part of their Venera p

Some sources claim that in the 1980s USSR already developed instruments that were capable of operating at surface environment of Venus as part of their Venera program. From [1]: While never deployed, a seismometer and thermopile battery were developed and tested, capable of operating indefinitely on the surface of Venus. [1] http://mentallandscape.com/V_Venera11.htm http://mentallandscape.com/V_Venera11.htm