A thick CO2 atmosphere with a surface pressure 92 times that of Earth’s atmosphere hides the planet’s surface from view

Facts about Venus

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Venus Atmospheric Missions

• Mariner 10 – Fly-by in 1973• Pioneer Venus – 5 probes in 1978• Vega 1 and 2 – 2 probes in 1985• Galileo – Fly-by in 1990• Europe’s Venus Express

(orbits in April 2006)

• Messenger (fly-bys October 2006 & June 2007)

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45 km = 100 Co

Cloud Tops

The “Greenhouse Effect” on Venus

Carbon dioxide cycle on Earth keeps us from being like Venus

But this cycle would not work if there’s no liquid water!

Single-celled floating

organisms like these

foraminifera construct fragile CaCO3 shells.

When the organisms die,

their shells sink to the ocean floor

and form limestone

deposits, thus trapping CO2.

Limestone deposits in today’s oceans

Spacecraft that have studied the surface of Venus

• Mariner 2 – 1962 – First planetary mission• Pioneer Venus – 1978 - Topography and

atmospheric probes• Veneras 8 – 14, 1975 – 1982 – Landers!• Veneras 15 & 16, 1984 – Orbital radars• Magellan – 1990 – 1994 – Orbital radar images,

topography and gravity data• Europe’s Venus Express, 2006

Venera 14 Soviet Lander - 1982

Landing Sites for Venera Spacecraft

Venera 14 views of surface of Venus

The surface of Venus, imaged by the Venera

14 Lander.

Upper image:CO2 atmosphere

results in reddish color.

Lower image:CO2 removed.

The dark rock is basalt!

Composition of the surface rocks of Venus.The rocks are basalt!

Magellan being launched from Space Shuttle

Topography of Venus from the Pioneer Venus spacecraft

The “continents” on Venus are as big or bigger than those on Earth

Maxwell Montes over 12 km high!

Maat Mons ~8 km highStill active?

Sapas Mons~400 km dia.

Cleopatra CalderaOn Lakshmi Planum

Tectonic features: Fotla Corona S.E. of Aphrodite Terra

Tessera rolling plains near Maxwell Montes

Rift zones

Stuart Crater

67 km diameterAurelia crater

32 km diameter

Unusual fluid ejecta at impact craters on Venus

Wind streaks – fine particles moved by wind

Isabella crater – Ejecta so hot it flows like lava

High surface pressure may help pancake domes form

Summary of Venus