[3] After separating from its flight platform on 19 December 1978, the Venera 12 lander entered the Venus atmosphere two days later at 11.2 kilometres per second (7.0 mi/s).

The SIGNE 2 detectors were simultaneously flown on Venera 12 and Prognoz 7 to allow for triangulation of gamma ray sources.

Venera 12 used its ultraviolet spectrometer to study comet Bradfield (C/1979 Y1) on 13 February 1980, and reported spectrophotometric data until 19 March 1980.

Results reported included evidence of lightning and thunder, a high 36Ar/40Ar ratio, and the discovery of carbon monoxide at low altitudes.

A design flaw prevented the lens caps from separating, resulting in all cameras failing to capture and return images.