Venera 9 was the first of a new generation of Soviet space probes (4V) designed to explore Venus, and designed on the basis of the M-71 and M-73 Mars platforms.
Launched by the more powerful Proton-K launch boosters, the new spacecraft were nearly five times heavier than their predecessors. Each spacecraft was comprised of both a bus and a lander, the former equipped with a powerful 11D425A engine capable of about 4,250 pound-force (1,928 kilogram-force or kgf) thrust and able to throttle down to 2,216 pound-force (1,005 kgf) of thrust.
For this series of missions, the 5,071-pound (2,300-kilogram) (mass at Venus orbit insertion) buses would serve as orbiters photographing the planet in ultraviolet light and conducting other scientific investigations.
The 1,455-pound (660-kilogram) landers, of a completely new design, employed aerodynamic braking during Venusian atmospheric entry and contained a panoramic photometer to take images of the surface. During the coast to Venus, they would be packed inside a 3,440-pound (1,560-kilogram) spherical re-entry pod with a diameter of about 8 feet (2.4 meters).
Without any apparent problems and two trajectory corrections (June 16 and Oct. 15, 1975), Venera 9’s lander separated from its parent Oct. 20, 1975, and two days later hit Venus’ turbulent atmosphere at a velocity of about 6.5 miles per hour (10.7 kilometers per hour). After aerodynamic deceleration, the cover of the parachute compartments was jettisoned at about 40 miles (65 kilometers) altitude, with two parachutes (one a drogue and the second to remove the upper portions of the heat shield casing) successively deployed.
Descent velocity reduced, as a result, from 820 to 492 feet per second (250 to 150 meters per second). At that point, a long drag parachute deployed and data transmission began. The drag parachute decreased descent velocity down to 164 feet per second (50 meters per second) before, finally, at 38.5 miles (62 kilometers) attitude, three large canopy parachutes deployed (with a total area of 1,937 square feet or 180 square meters).
Four seconds after deployment, the lower hemisphere of the heat-shield casing was discarded. The now fully deployed descent vehicle descended for approximately 20 minutes before the main parachutes were jettisoned. The rest of the descent was slowed only by the capsule’s own disc-shaped aerobrakes.
The lander impacted on the surface at a velocity of approximately 23 feet per second (7 meters per second). Pravda noted on Feb. 21, 1976, that “the landing units, which are thin-walled toroidal shells, were deformed [as planned] during landing, thereby absorbing the energy of the impact and assured an oriented position of the descent vehicle on the planet.”
Landing occurred on the planet’s dayside at 05:13:07 UT Oct. 22, 1975. (Times were only announced for reception of landing signal on Earth). Landing coordinates were within a 93-mile (150-kilometer) radius of 31.01 degrees north latitude and 290.64 degrees east longitude at the base of a hill near Beta Regio.
During its 53 minutes of transmissions from the surface, Venera 9 took and transmitted the very first picture of the Venusian surface, taken from a height of about 35 inches (90 centimeters). These were, in fact, the very first photos received of the surface of another planet.
The lander was supposed to transmit a full 360-degree panorama, but because one of the two covers on the camera failed to release, only a 180-degree panorama was received. Illumination was akin to a cloudy day on Earth. The image clearly showed flat rocks strewn around the lander.
The Venera 9 orbiter meanwhile entered a 938 x 69,700-mile (1,510 × 112,200-kilometer) orbit around the planet at 34 degrees 10 minutes inclination and acted as a communications relay for the lander. It became the first spacecraft to go into orbit around Venus.
The Soviets announced March 22, 1976, that the orbiter’s primary mission, which included using French-made ultraviolet cameras to obtain photographs in 746-mile (1,200 kilometer) swaths, had been fulfilled.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.