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Planetary News: Venus (2007)

Venus Express Celebrates Two Years in Space

 

November 12, 2007
Venus Express image of Venus surface temperatures
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Venus Express image of Venus surface temperatures
This map of the surface of Venus is a composite of about 1,000 individual Venus Monitoring Camera (VMC) images taken from April to August 2007. The images were taken at an infrared wavelength of 1 micron, at which Venus' atmosphere is somewhat transparent. The colors correspond to the apparent temperature of the surface; blue colors are areas about 40 degrees Celsius (70 degrees Fahrenheit) cooler than red-orange colors. On Venus, as on Earth, cooler temperatures generally prevail at higher elevations; the blue areas correlate with areas of high, mountainous topography, while orange areas correlate to Venus' broad volcanic lowlands. However, some of the variation in apparent temperature could arise from variations in mineralogy across the surface. Venus Express scientists are studying images like these to look for regions that are anomalously warm given their altitude, in the hopes of finding active volcanic centers. It is unknown whether Venus has currently active volcanoes or not. Credit: ESA / VMC / MPS / IPF-DLR

Venus Express, which launched two years ago this week, has has recently peeked through the planet's thick veil of clouds and sent new images of its surface.

Venus' surface is a scorching 735 kelvins -- 462 degrees Celsius or 864 degrees Fahrenheit -- and emits a tremendous amount of infrared radiation. All of this radiation is scattered numerous times by its thick 25-kilometer (15-mile) layer of clouds before it escapes into space. This gives Venus a weak glow, but also makes it hard for an orbiting satellite to get a true picture of the planet's countenance.

Despite the thick haze, infrared light, invisible to the naked eye, can escape at certain wavelengths through spectral windows. ESA's Venus Express carries the Venus Monitoring Camera (VMC), which has used one of the spectral windows to see through the haze and map the surface of Venus' night side. 

Unveiling Venus

The areas mapped with the VMC cover the Beta and Phoebe Regios in the mid- to equatorial latitudes visited in the 1970s by several Soviet Venera and U.S. Pioneer Venus landers. The pictures reveal highlands and mountains of elevation up to 5 kilometers (3 miles) above Venusian "sea level". Even when looking through the infrared window, observing Venus' surface from orbit is similar to looking though a frosted window, when one can only see the silhouette of an object.

The mapped area includes some of the most typical geological features on Venus. Beta Regio and Phoebe Regio represent tesserae -- some of the oldest terrain on the planet. In 1990, the radar on board the NASA's Magellan spacecraft detected anomalously high reflectivity of the tops of Rhea Mons and Theia Mons. This indicates the presence of still unknown conductive, semiconductive, ferroelectric, or ferromagnetic materials.

The images are being used to study the variation of mineralogical composition on Venus and are being correlated with the topography and radar reflectivity of the surface. They are also being used to search for ongoing volcanic activity.