Mission Type: Flyby
Launch Vehicle: Modified SS-6 (Sapwood) with 2nd Generation Upper Stage + Escape Stage; 8K78M
Launch Site: Tyuratam, Baikonur Cosmodrome, USSR; NIIP-5 / launch site 1
Spacecraft Mass: 958 kg
Spacecraft Instruments:
1) three-component magnetometer
2) imaging system
3) solar x-radiation detector
4) cosmic-ray gas-discharge counters
5) piezoelectric detectors
6) ion traps
7) photon Geiger counter
8) cosmic radio emission receivers
References:
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi

NSSDC Master Catalog, http://nssdc.gsfc.nasa.gov/nmc/

Although the 3MV-3 and 3MV-4 type spacecraft were originally intended for Mars exploration, the Soviets re-equipped three of the series, left over from the 1964 Mars launch windows, for Venus exploration in 1965. This particular vehicle was scheduled to fly past the sunlit side of Venus at no more than a 40,000-kilometer range and take photographs.

During the outbound flight, communications with the spacecraft were poor. Immediately before closest approach in late February 1966, ground control commanded to switch on all the onboard scientific instrumentation. The closest approach to the planet was at 02:52 UT on 27 February 1966 at about a 24,000-kilometer range.

After its flyby, when the spacecraft was supposed to relay back the collected information, ground
control was unable to regain contact. Controllers finally gave up all attempts at
communication on 4 March. Venera 2 eventually entered heliocentric orbit.

Later investigation indicated that improper functioning of 40 thermal radiator elements caused a sharp
increase in gas temperatures in the spacecraft. As a result, elements of the receiving and decoding units failed, the solar panels overheated, and contact was lost. Ironically, the scientific instruments may have collected valuable data, but none of it was ever transmitted back to Earth.