Venera 11

Lore & Background

Venera 11 launched on 9 September 1978. Its lander separated from the flight platform on 23 December 1978 and entered the Venus atmosphere two days later at 11.2 km/s. After aerodynamic, parachute, and atmospheric braking, it made a soft landing at 06:24 Moscow Time (03:24 UT) on 25 December, with a touchdown speed of 7 to 8 m/s. The landing coordinates were 14°S 299°E. The lander transmitted information to the flight platform for retransmittal to Earth until the platform moved out of range 95 minutes after touchdown.

Reader's Guide

Venera 11's flight platform carried solar wind detectors, ionosphere electron instruments, and two gamma-ray burst detectors—the Soviet KONUS and French SIGNE 2. The SIGNE 2 detectors flew simultaneously on Venera 12 and Prognoz 7 to allow triangulation of gamma-ray sources. Before and after the Venus flyby, Venera 11 and Venera 12 yielded detailed time-profiles for 143 gamma-ray bursts, resulting in the first ever catalog of such events. The last gamma-ray burst reported by Venera 11 occurred on 27 January 1980. The lander carried instruments to study temperature, atmospheric and soil chemical composition, and a device called Groza to search for lightning. Both Venera 11 and Venera 12 landers had two cameras designed for color imaging, but each failed to return images when the lens covers did not separate after landing due to a design flaw. The soil analyzer also failed. Results included evidence of lightning, a high Ar36/Ar40 ratio, and discovery of carbon monoxide at low altitudes. The mission ended in February 1980; Venera 11 remains in heliocentric orbit.

Did You Know?

• Venera 11's lander entered the Venus atmosphere on 25 December 1978 at 11.2 km/s.
• The lander's two color cameras failed because the lens covers did not separate after landing.
• Venera 11 and Venera 12 produced the first ever catalog of gamma-ray bursts, with 143 events.
• The flight platform carried both a Soviet KONUS and a French SIGNE 2 gamma-ray burst detector.