Sponge: What is unique about Venus’ rotation on its axis?

Exploration: Approximately 20 spacecraft have visited Venus since the 1970’s. Most of them have been Soviet.

The U.S. sent Mariner 2, 5 and 10. The Soviet Union sent Venera 4-12, all of which were designed to land on Venus.

Mariner 6

The early Venera spacecraft were destroyed by atmospheric pressures and/or high temperatures.

Finally, in 1970, Venera 7 soft-landed on the planet surface and sent back surface data and the first pictures from the surface of Venus.

None of the Venera spacecraft survived for more than one hour on the surface. They were all cooked or crushed.

Venera 13

Venera 13

Venera 14

The atmospheric pressure on the surface of Venus is 90 times that of Earth. That is equivalent to an underwater depth of 1km. (Scuba divers can’t go much below 100m.)

The surface temperature is 750K The surface temperature is 750K. That is twice the temperature of a kitchen oven; hot enough to melt lead.

The U. S. sent Pioneer Venus in 1978 The U.S. sent Pioneer Venus in 1978. Also Magellan was launched in May of 1989 from the space shuttle. It made all previous data obsolete.

The Venusian atmosphere is more massive and extends to greater heights than Earth’s. The temperature drops rapidly from 750K to cooler in the upper atmosphere than on Earth.

The surface winds move at less than 2 meters per second (4 mph) The surface winds move at less than 2 meters per second (4 mph). The atmosphere is composed primarily of CO2 (96.5%) and N2 (3.5%). Very little H2O.

There is a highly reflective cloud layer composed of H2SO4 (H2O + SO2) There is a highly reflective cloud layer composed of H2SO4 (H2O + SO2). This causes Venus’ high albedo (0.7).

The great amount of CO2 causes a greenhouse effect far greater than that on Earth.

The higher levels of CO2 caused the temperature to increase The higher levels of CO2 caused the temperature to increase. These higher temperatures caused water to be evaporated away.

As more and more water evaporated, the levels of CO2 increased and the cycle continued.

This cycle is called The Runaway Greenhouse Effect.

Rapid atmospheric circulation causes the night-time side of Venus to be the same temperature as the day-time side and the poles to be the same temperature as the equator.

One unique feature of the cloud cover is the vortex over the south pole of Venus. No explanation has been found for this feature.