A thick CO 2 atmosphere with a surface pressure 92 times that of Earth’s atmosphere hides the planet’s surface from view

Facts about Venus * * 462 C o * *

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 C o 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 CaCO 3 shells. When the organisms die, their shells sink to the ocean floor and form limestone deposits, thus trapping CO 2.

Limestone deposits in today’s oceans

Spacecraft that have studied the surface of Venus Mariner 2 – 1962 – First planetary mission Pioneer Venus – 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

Landing Sites for Venera Spacecraft

Venera 14 views of surface of Venus

The surface of Venus, imaged by the Venera 14 Lander. Upper image: CO 2 atmosphere results in reddish color. Lower image: CO 2 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 high Still active?

Sapas Mons ~400 km dia.

Cleopatra Caldera On Lakshmi Planum

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

Tessera rolling plains near Maxwell Montes

Rift zones

Stuart Crater 67 km diameter Aurelia 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