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Interplanetary Probes from Earth Visit Venus

Venus Express        Venus Probes Timeline        Venus Transit 2004

Magellan     Pioneer-Venus 1     Pioneer-Venus 2     Other Past Probes     Future Probes     VEsat
Venus Express

An ESA artist concept of the Venus Express interplanetary probe over Venus
ESA artist concept of Venus Express
The European Space Agency in Fall 2005 will send Venus Express to probe the second panet out from the Sun. The spacecraft will explore the Venutian atmosphere where scientists want to understand the origin of violent winds which blow around the planet.

Astronomers also want to understand why Earth and Venus developed in radically different ways. Venus is similar in diameter and mass to Earth, yet that planet has evolved differently, with a surface temperature hotter than a kitchen oven — in fact, hot enough to melt lead. Venus is enveloped by a thick atmosphere that is a choking mixture of noxious gases.

To study that atmosphere, and make the first radar soundings below the planet's surface, Venus Express will reuse the basic spacecraft design of ESA's Mars Express probe and will carry the kind of instruments originally developed for Mars Express and Rosetta.

Venus Express will look at the planet's environment from the surface up to the top of the atmosphere. Russia will launch Venus Express on a Soyuz rocket from its Baikonur Cosmodrome in Kazakhstan in October or November 2005.

Magellan

The interplanetary space probe Magellan left Earth in 1989 and fell into orbit around Venus August 10, 1990. Since then, it has sent back spectacular radar images for a new, more-detailed map of Earth's cloud-shrouded sister planet.

NASA had trouble holding a steady radio contact with the spacecraft for a time as it whirled around Venus. Even so, spectacular images of rugged terrain were received.

Magellan completed one complete mapping of 90 percent of the surface of Venus with radar able to peer through the blanket of thick clouds which block visible light for optical cameras, then went into a second mapping cycle.

Noodle pictures. Magellan's Venus pictures reminded geologists of California earthquake faults, Hawaiian volcanoes, the rift valleys of East Africa and Europe's Rhine Valley. The strips of photos covering territory 1,000 miles long by 15 miles wide, called "noodle" pictures, depicted a violent Venus-scape sculpted with long, parallel valleys and ridges“like those between the Rocky Mountains and the Sierra Nevada range“as well as deep impact craters, jagged quake faults and expansive lava flows similar to those on Hawaii and in the Snake River plains of Idaho.

Overlapping lava flows six to ten miles wide, of different ages, were bright and dark splotches in the photos. Many Venus-quake faults and fractures suggested movement of the planet's crust had shaped the landscape. Parallel sets of elongated valleys and ridges looked like the basin-and-range area of the intermountain region of Utah and Nevada, or the Great Rift Valley in eastern Africa.

Apparently, part of Venus' crust had been stretched apart. Zigzag lines across the surface were tinsel fractures caused by pulling the crust apart, like the the rift valleys in East Africa or the Salt Trough earthquake fault under California. A pit crater about a mile wide in the photo, like depressions on the slopes of Hawaiian volcano Mauna Lea, may have been volcanic in origin, not the result of a meteor impact. The Devana Chasm, a giant valley, had fault patterns like those in the Rhine Graven region of Germany.

Pioneer-Venus 1

NASA's Pioneer-Venus probe is a small satellite still orbiting Venus. The U.S. sent two interplanetary Pioneer probes to Venus in May and August 1978, one to orbit the planet and the other to deliver four smaller probes to Venus.

Pioneer 12, also known as Pioneer-Venus 1, went into orbit around the planet December 4, 1978. Its highly-elliptical path around Venus brought it to within 100 miles of the surface to do radar mapping, cloud studies and magnetometer readings.

A NASA Image of the Planet Venus
VENUS
Solar Wind. Pioneer-Venus 1 still is in orbit around Venus, using radar to map the planet surface and send back data about the solar wind. The spacecraft intercepts particles in the solar wind as they pass Venus, flying out from the Sun during the 11-year sunspot cycle. Pioneer-Venus 1 reportedly has less than five lbs. of fuel left but that amount should keep it in proper orbit around Venus until at least 1992.

Radar maps suggested plateaus, volcanoes, and valleys on Venus larger than similar features found on Earth. Previous radar pictures made from Earth, and from Soviet spacecraft at Venus in 1983, displayed lava flows, volcanic craters and craters from meteorite impacts.

Pioneer-Venus 2

Pioneer 13, or Pioneer-Venus 2, was one big probe carrying four smaller probes to be dropped into the atmosphere of Venus. The mothership fired one large 160-lb. probe toward the surface of the planet November 15, 1978. Later, on November 19, it sent three smaller 50-lb. probes.

The probes penetrated the atmosphere of Venus at different locations on December 9, 1978, gathering data and relaying it back to Earth as they descended and hit the planet. One small sounder probe actually survived the hard landing and transmitted data for 68 minutes from the surface. The main Pioneer-Venus 2 mothership also arrived at Venus December 9, entering the upper atmosphere as a probe. It burned in the atmosphere.

Other Past Spacecraft

The first spacecraft from Earth to visit Venus was Mariner 2 back in 1962. After that, the planet was visited by more than 20 interplanetary probes, including Pioneer Venus. The Soviet spacecraft Venera 7 was the first ever to land on another planet. The Soviet probe Venera 9 returned the first photographs of the surface of Venus. Recently, the U.S. spacecraft Magellan orbited the planet and used its radar to draw detailed maps of the surface.

Future Spacecraft

VESAT

The U.S. space agency had been considering exploring the atmosphere of Venus again with a probe known as Venus Environmental Satellite (VESAT), part of the Discovery series of low-cost, highly-focused science spacecraft. If it ever would be funded and launched, VESAT would orbit the planet and examine the atmospheric chemistry and meteorology of our cloud-covered neighbor using an imager, near-infrared spectrograph, a temperature mapper and an X-band radar.

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